Car Heater Blows Cold – Auto Service Tips
October 10, 2009 1:52 pm DIY, How To Auto Repair
Heater hose clamps like pictured can be removed easily with special hose clamp tools.
Summary: In this auto service repair article, we cover how car heaters work. Knowing how the automotive heater system is designed to work, allows the car owner or auto tech to diagnose problems more quickly and easily. Car heaters are designed much differently than home heaters, therefore diagnosing and repairing auto heaters requires different service procedures. Auto service tips and information provided in this car repair article is written by a master automotive technician that has many years in the field. The info. is provided in simple language that is easy to understand by anyone – experienced in auto service or not.
It’s always best to have a basic understanding on how a particular system works, to be able to diagnose problems easier. When a car heater blows cold air, there are several possibilities that should be considered. Read on to to learn more. Many people are unaware that there’s NOT an electric element in a car’s heater system. Heater elements are common in portable heaters used in the home – however automobiles use coolant from the car engine’s cooling system to transfer heat to the passenger compartment, through the use of a heater core. That’s why a car heater doesn’t start blowing warm air until the vehicle reaches operating temperature. The heater core looks similar to a small radiator – it has coils and fins to transfer heat to the air. The car engine’s coolant is pumped through the heater core while the fan (also called a blower), pushes air through the heater core fins. When air blows through the heater core fins the air is warmed and in turn heats up the passenger compartment.
One of the most common causes of a car heater blowing cold air is from low coolant. As stated before, coolant is what warms the heater core – if the coolant is low, there may not be enough heat transfer from the heater core to the air to heat the passenger compartment. When it ’s cold outside, low coolant may not cause the engine to overheat right away. If it did cause the engine’s temperature gauge to read hot, the driver would be warned and low coolant would be discovered more quickly. The point is, when checking the heater be sure the radiator is full of coolant. Once the coolant is verified to be full, feel the heater hoses that go to the firewall. With the engine at normal operating temperature, BOTH of the heater hoses should be hot to the touch. If only one is hot, this indicates there is a blockage in the heater core or there is air trapped in the heater core preventing proper flow. Using a Lisle coolant funnel is best way to remove air from a car’s cooling system. If the coolant is really brown, has been neglected, or if stop leak has been used at some time in the car’s service history, the heater core could be stopped up. The blockage can sometimes be cleared by removing the heater hoses and using a garden hose with a sprayer to flush the heater core out. If neither of the hoses are hot to the touch, there could also be a malfunctioning heater control valve, if used on the model you’re working on. Check for presence of a heater control valve by following the heater hoses back to the engine. Sometimes, a vacuum line could have a break causing there to be no vacuum to operate the valve. Also it should be noted that if this is your first winter with this car (and you’re unfamiliar with the car’s repair history), the previous owner could have by-passed the heater core due to a leak. When a heater core leaks, the passenger side carpet will become soaked with coolant. This should not be confused with an AC (condensation) water leak. The labor involved to change a heater core is usually several hours depending on the model. This is the reason some people will loop the heater hoses together with a 5/8″ union – by-passing a leaking heater core instead of repairing it properly.
After the previous steps are taken to insure the heater core is in the loop, the coolant is full and hot water is circulating in and out of the heater core, read the following regarding the HVAC (Heating, Ventilation & Air Conditioning) case. Doors within the heater case are either controlled by electric actuators, cables or vacuum motors. Adjust the heat control to both extremes while listening for movement of the blend door. With a cable operated heater door it’s easiest to hear the door thump when it closes. If the door is not operating, find the door that controls the airflow across the heater core. If there is an electric motor that controls the door, tapping on it can sometimes make it work temporarily for testing purposes. A vacuum operated motor needs vacuum to work, so using a hand-held vacuum pump for testing is usually the easiest way to check operation. If the vacuum motor does not hold vacuum, the diaphragm is leaking requiring replacement. To go deeper into diagnosis of the AC control head’s function and diagnosis, specific vehicle repair diagrams may be needed or help from technician that has experience with the specific model may be most beneficial.
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Tucson Automotive Repairs :
Date: October 12, 2009 @ 3:11 pm
Very informative read about heating and cooling systems. We try to give our customers very straightforward information like this when answering their questions about automotive repair; it’s nice to see other people taking the same approach. Thanks for the great read!
Adam :
Date: November 18, 2009 @ 2:08 am
I have a 97 Chrysler sebring 2.5 v6 that has a heater problem. The car only has warm or hot air after driving around for a while. Even when the temp gauge reads normal engine temperature, it still takes several min for warm air to start blowing out of the vents. Do you have any advice and thank you in advance.
dennisb - Auto Tool Sales :
Date: November 18, 2009 @ 8:01 am
Adam, the tips mentioned in the article could help. Full coolant? Feeling the inlet and outlet hoses to make sure coolant is flowing through the core and making sure there’s no air in the system.
susan Davison :
Date: November 19, 2009 @ 12:03 am
i have a chrysler sebring 2001. my heater blows hot except when im idling. it still blows air but cool when i put it in park and idle. Im having trouble also with my cruise control not working when i turn on my lights or use my (i think my right) turn signal when switching lanes. The weird thing is the cruise control thing is intermintent. I was surpised to get to use my lights and cruise control the other night only to have the turn signal shut it off. HELP. I just had the transmission fixed. Since then Ive heard an exhaust sound from engine. When I took the mechanic for a ride to hear it, it wasnt doing it then. sounds like I have a glass pack on it. Can you help me sort this out?
dennisb - Auto Tool Sales :
Date: November 19, 2009 @ 9:34 am
Susan, you may have some air in the cooling system affecting the heater, this is quite common.
Sounds like an electrical short possibly in the steering column affecting the lights and cruise.
The exhaust sound may have been a dust shield interfering with the flywheel – exhaust leaks will not fix themselves, but if a shield was lightly rubbing on the flywheel, it could have worn away enough to not be touching anymore now. If it continues to make noise you may want to take it to an exhaust shop.
Nicole :
Date: November 21, 2009 @ 8:20 pm
I have a 2002 Nissan Altima. I have the same problem as Susan with my car heater, and have had it 3 winters in a row now. My heater only blows warm air when the car is actually driving (and I typically have to be going over 40mph for the warm air to kick in), and it blows cold when I go slower than 40mph or am stopped. The first year I took it to a shop and they fixed it. They said that it was caused by a gear coming off the motor that controls the heat. I took it to another shop this year to get it fixed and they first told me it was the thermostat and put a new one in, which didn’t work. They then told me that it had to be the water pump if it wasn’t the thermostat so they put a new water pump in and said it was fixed. Almost immediately after getting it back, I realized the probelem is still there. Plus, now my air conditioner is not working either when it worked absolutely fine before taking it in to get the heat fixed! So now I have paid $250 to not only have my heat problem still not solved, but they messed up my a/c in the process and refuse to give me a refund or to take another look at it and fix it correctly at no charge. Any ideas what the real problem could be since it apparently wasn’t the thermostat or water pump? Could both the a/c and heat problem be caused by the motor again?
dennisb - Auto Tool Sales :
Date: November 21, 2009 @ 8:58 pm
Nicole, The gear coming off for the blend door would affect the heat at ALL vehicle speeds. The reason the car is blowing warm air ONLY when your driving, could be due to the water pump pumping more water through the heater core, since the engine is turning the pump faster. Many Nissans have a problem with the radiator cap rubber seal swelling slightly preventing coolant from traveling back and forth from the coolant reservoir (plastic bottle) and the radiator. If this happens and the cooling system has a small leak (from a hose connection for instance) the system can end up with air in it, even though there is some coolant in the overflow reservoir. Particularly in Nissan vehicles if air is in the cooling system, an air-lock in the heater core can prevent the heater from working properly. See the related article (click the image below) to learn how to purge the air from the cooling system. As far as the AC, that could be a totally separate issue – checking the AC is the only way to determine what the problem is with it.
DJ :
Date: November 30, 2009 @ 7:25 pm
I’m looking to buy a 2000 Eclipse, the person that is selling it says that the only problem is in the heating system. He says it blows hot on the left (I’m assuming the passenger side) and cold on the right (again assuming its the driver side) when the heat is on. After reading the article it sounds like it could be a plugged hose or possibly one of the doors are malfunctioning. Does this sound right to you? And if it does how involved would it be to repair the door? Thanks
dennisb - Auto Tool Sales :
Date: December 1, 2009 @ 7:35 am
I would first check the simple things like an air lock in the system. However, it does sound like there could be a malfunctioning HVAC door or actuator. By looking at a parts breakdown of the case assembly, determine which actuator and door control the side that is not working properly *left and right are always determined when sitting in the vehicle, not standing in front of the car. After pinpointing which actuator or door assembly is at fault, the amount of labor required can be looked up in a repair manual – sometimes access is easy and other times very labor intensive (ie dash removal for access). Depending on how much trouble this is to fix, this repair could be a deal breaker.
Adam :
Date: December 5, 2009 @ 1:24 am
Thanks for all the comments dennisb, I would like to know your comments on if a rad or heater core flush would fix my heat problem. And if so could you tell me a bit about the procedure.
dennisb - auto tool sales :
Date: December 5, 2009 @ 7:23 pm
Adam, a plugged heater core could be the problem. Checking the temp of both hoses like I mentioned in the article above is where I would start to help determine if it is or not. If it is plugged, flushing the heater core can be done with a garden hose with a sprayer attached, be sure to bleed the air out of the system as mentioned in the above article.
Domingo Roxas :
Date: December 7, 2009 @ 3:40 am
Car ac vents blow hot air, when it’s the cool air that is needed (tropical country). This makes inside of car too hot. What is wrong with the system?
dennisb - Auto Tool Sales :
Date: December 7, 2009 @ 7:22 am
Domingo, you may want to check out some of our air conditioning articles, especially the one about AC gauge readings explained.
George :
Date: December 7, 2009 @ 11:20 pm
Hey dennisb, I have a Concorde 2000 3.2l, it seems like the heater is not blowing hot air, I just replaced thermostat and filled it with coolant. Even when idle is not blowing hot air, sometimes it looks like blows warm air after a while, actuator seems working since a made self diagnose by pressing floor, mix and defrost and no errors were given. No leaking, what could be the issue???
dennisb - Auto Tool Sales :
Date: December 8, 2009 @ 7:31 am
George, just filling the coolant is not good enough with most modern vehicles, since air can get trapped easily. Some cars even have bleeder screws, I remember the 2.7 engine in the Concorde, definitely has a bleeder screw in the top coolant housing – not sure about the 3.2 Liter. And as I mentioned before the Lisle coolant funnel does wonders to burp air out that can definitely cause an air lock in the heater core. You could have other problems with your Concorde, but you would be surprised how many times it’s just air in the system.
A recent article that about a Dodge Durango, which had poor rear heater performance ended up having a blown head gasket which continuously introduced air from the combustion chamber into the cooling system causing a void that never could be purged. Not saying that you have a blown head gasket, but this is something that people should consider, if air keeps bubbling up when using the coolant funnel and never seems to purge completely.
Jess :
Date: December 9, 2009 @ 2:56 am
Hey Dennisb, great article! I have a 1999 Toyota Camry CE, and recently the coolant temperature guage has been acting weird. The temperature reading drops after I turn on the car heater, and after some time less hot air starts coming out of the vents. When I stop the heater, the temperature guage goes back to normal. Also, when I am going at highway speeds and suddenly brake, the temperature guage again falls. It goes back to normal after some time. Can you please help me out on what could be the problem? Thanks!
dennisb :
Date: December 9, 2009 @ 4:23 pm
Jess, I would first check the coolant level and make sure there’s no air in the system.
After you’re sure there’s no air – you may also want to check the accuracy of the temperature gauge, by using a scan tool to access engine data and to make sure the temps are the same. I don’t see why stopping suddenly would change the temperature of your engine – so it could be a gauge issue or possibly wiring.
The fact remains the engine’s temperature varying slightly shouldn’t affect the heater performance that much, there should be heat available.
Jamie :
Date: December 10, 2009 @ 1:02 pm
I have a friend with a 2000 Saturn L series and is only blowing cold air. It doesnt get warm at all! I am trying to help because its been in the negatives and teens this week! Trying to keep friends warm!!!
Dustin Ealy :
Date: December 15, 2009 @ 1:06 am
My girlfriend’s car isn’t blowing hot air when the heater is on. I was thinking it could be the thermostat because that is what was wrong in my car when i had the same problem. Is this possible.
dennisb - Auto Tool Sales :
Date: December 15, 2009 @ 7:25 am
Dustin, A thermostat usually fails in one of a couple of different ways.
1. Thermostat doesn’t open – this in addition to causing the heater not to work will also make the engine temperature over-heat.
2. Thermostat stays open – if it stays open all the time, or opens too early (before the engine reaches the target operating temperature) the heater will not blow as warm as it should. If this is the case, usually after the car has ran awhile the vent temperature will increase gradually (at varying rates depending on the ambient temp).
So basically, check the car’s temperature gauge to see if the engine is running at the normal operating range – if it is and at that time the heater isn’t working correctly there probably is a different cause.
TRACY :
Date: December 18, 2009 @ 2:44 pm
Hi, I have a 1999 Nissan Altima. When my car heats up the temperature gauge does not go to the middle (in between hot and cold) as usual. It seems to only stay to the cold side which is making the heat in my car not very hot. I have heard about cars running hot before, but not running cold like my is doing. I have had the car for 2 1/2 years and this is the first time this has ever happened. I haven’t had any problems with the heat or air conditioning since buying the car. But also haven’t had any reason to maintain the heat or air and I didn’t know that there was anything in particular to do, to keep it maintained. Do you know what could be wrong? Thanks
dennisb - Auto Tool Sales :
Date: December 19, 2009 @ 9:07 am
Tracy, regarding maintenance the coolant condition and level should be checked at every oil change. Typically the air conditioning doesn’t really need to be checked unless the performance isn’t up to par. Some cars do have a cabin air filter (yours does not) that should checked similar to the filter in your home central air system. To read more about cabin air filters and problems with low airflow, see our related repair article. The outside temperature can affect the operating temperature of your engine some. If it’s really cold outside, it could take a little longer to reach full operating temp. Based on what you’re describing, I would check the thermostat, since it may be opening too soon. The thermostat normally stays closed when the car is first started, to allow the engine time to heat up quickly to it’s optimum temperature before it allows the flow of coolant throughout the system. Also since you have a Nissan, which has a heater system, which is more prone to being affected by low coolant and air in the system – I would use the funnel mentioned previously in this car repair article.
ROBERT :
Date: December 19, 2009 @ 2:11 pm
hi dennisb my wifes car blows only cold air,I ran the car,thermostat seems to work fine. I felt the hoses neither are hot.the car is a 98 PLYMOUTH BREEZE.what do you suggest?thank you
dennisb - Auto Tool Sales :
Date: December 19, 2009 @ 2:15 pm
Robert, coolant flow needs to go to the heater core – there may be a heater control valve malfunctioning (if one is used on that model). I would look to see if a heater control valve is in the heater hose coming from the engine.
Nathan :
Date: December 19, 2009 @ 11:33 pm
dennis, I have 1998 plymouth neon and just all the sudden the car is overheating and some water dripping out of the radiator cap where the car is running hot and the heat is cold the fan will still blow but the air is cold. Is this the thermostat or what?
dennisb - Auto Tool Sales :
Date: December 19, 2009 @ 11:55 pm
Nathan, Before checking the heater, the car’s engine needs to be running at a normal temperature. Yes, it could be a thermostat, a cooling fan or any other number of causes. After the overheating problem is diagnosed, the heater most likely will work.
IVAN :
Date: December 20, 2009 @ 9:27 pm
Hi Dennis B.
I have a pontiac Trans sport 1996. I had so many opinions regarding the heater system since it stopped working. There is no hot air coming in the car making it impossible to drive in snow. I changed the blower motor, thermostat, filled with coolant and it would not work. How could i check the heater core, how can i locate the heater core in my car and know if it is working?
The low coolant light is on in my panel, but the car is filled with coolant. maybe that might be a clue.
Please help me out.
thanks
dennisb - Auto Tool Sales :
Date: December 20, 2009 @ 9:39 pm
Ivan, Your 1996 Pontiac Transport most likely has a 3.4 V-6 with at least one bleeder screw in the coolant pipe (if I remember correctly). First off I would check to make sure all the air is out of the cooling system using a Lisle coolant funnel and bleeding the air out with the bleeder screws. This along with the other tips I’ve included in the article should help to pinpoint the problem.
Low coolant light – if the coolant is at the correct level in the reserve bottle and the radiator, the switch is probably stuck or defective. The coolant level switch in your vehicle is most likely just below the radiator fill cap in the radiator (in some vehicles, it is in the plastic reserve bottle/coolant reservoir). In either case that would not prevent the heater from working as long as the coolant level is actually full.
Dee, Belfast, N.Ireland :
Date: December 22, 2009 @ 5:59 pm
Hi dennisb,
Great site with informative & prompt advice, great work!!!
I’m hoping you can help me out a little here: with snow and -3° here in Belfast, Northern Ireland, I need my Renault Laguna’s heater to be working, but I’ve been having problems over the past days:
The car has been blowing cold air when idle although warm when I’m driving. In order, I’ve checked the coolant level which is fine. With the car just started I then felt the inlet and outlet hoses (under the hood) going into the Heater Core/Matrix to establish if the inlet-hose got warm first then the outlet shortly after. The inlet hose did get hot in a short while, but the outlet hose took a few MINUTES later to heat up and wasn’t as warm as the inlet hose, thus indicating it could be an air-lock or blockage.
As mentioned on other sites I then drove the front of my car up onto the small metal ramps – to ensure the coolant tank/reservoir is at the highest point, then with the cap off I started the car and let it run idle for a few minutes while giving it a few gentle revs – in order to let any trapped air in the system to escape. Some gurgles/bubbles did come via the coolant tank (with cap off) although I still run it a little longer while keeping a close eye on the coolant level (ensuring their was enough inside…). However, the problem persisted.
Carefully using a screw-driver to prise open the safety-clip, I then removed the two hoses, inlet & outlet (joined together at the ends) going into the heater core/matrix, behind the dash but under the hood. This revealed the two holes leading into the heater matrix, still under the hood, (no work inside the car!).
I then pressed a garden hose-nozzle into the outlet hole in order to BACK-FLUSH the matrix, which is safe to do. Some liquid-crud and dirty coolant came out through the inlet hole as expected. I did this until the water came out clear through the other hole. I then re-connected the two hoses to the matrix-holes under the hood, ensuring the clip/s were intact again.
The problem still persisted, albeit there were times I thought it was sorted due to some luke-warm air coming through the vents for a few seconds, but then cold again.
I then replaced the thermostat with a new and original one, but still the problem persists.
I’m wondering if there’s still more trapped air in the system, or if a vent may be stuck or something, as I’ve heard the odd gurgle behind the dash sometimes when driving and, warm air comesout the vents only when I’ve been driving at least a mile or two, but goes cold again when I slow or stop.
Note: I’ve tried to clearly detail what I’ve done so far to give you a better picture, and in case the actions help someone else…
Maybe you can give me a pointer mate?
Many Thanks!
Dee
Dee, Belfast, N.Ireland :
Date: December 22, 2009 @ 6:04 pm
Ps. My two hoses going into the heater matrix resemble those as shown in the picture at the top of the above topics, albeit mine are joined like a double-barrel shotgun at the end. Cheers!
dennisb - Auto Tool Sales :
Date: December 22, 2009 @ 10:13 pm
Dee, it’s possible even though you were able to back flush the heater core that it still may be restricted. For the heater core to work properly there needs to be a unrestricted flow to allow enough heat exchange. When the garden hose is hooked up and water being ran into it – the flow of water coming out of the heater core should just as great. Reduced flow will cause the heater not to work sufficently.
Dee, Belfast, N.Ireland :
Date: December 24, 2009 @ 7:08 am
I think you’re right bud. When I insert the hose to one hole (outlet) the water flows out the other (inlet) with a good flow. However, when I flush through the inlet the water trickles out the oulet hole – possibly indicating a restriction.
I’ve now fully bled the system with not a single bit of air trapped inside, therefore it has to be a blockage in the matrix. I’ve read about carefully inserting diluted Hydrochloric Acid into the matrix for about 5 mins, before giving it a good flushing out. The acid is meant to really help in breaking up any gunk etc inside.
Providing it’s nothing Alkali or caustic based going inside the matrix which can badly affect aluminium (which of course the matrix and radiator is made up of.
Here’s an EXCELLENT link which I’ve also been using which shows clear digital photos and details of exactly what to do step-by-step (for a Renault Laguna, but may suit other cars): http://www.renaultforums.co.uk/showthread.php?t=5107
Thanks again pal and I hope you and yours have a very Merry Christmas!!
Regards,
Dee
dennisb - Auto Tool Sales :
Date: December 24, 2009 @ 11:26 am
Thanks Dee. BTW 70° at the moment here in Florida
Merry Christmas!
damar :
Date: December 25, 2009 @ 4:44 am
Hey dennisb I have 1998 acura rl 3.5
I replaced my thermostat but my coolant is brownish will that effect the heat coming into my car because its not as hot as it should be. Also sometimes when im driving the blower starts to blow cooler I located the bleeder screw and there seems to be no air in the system helppppp me please.
Dee, Belfast, N.Ireland :
Date: December 25, 2009 @ 7:25 am
Aaaa, it’s Florida you’re based in!
I’ve been with the family the last two years – staying at my father-in-law’s villa (Blossom Hill Loop, off the 127 & 192, near the Wal-Mart and Lowes DIY.
We love Florida. I was even offered a job there with my company and was so close to taking it. It just didn’t pay well enough though and so couldn’t afford to go (while supporting my family back here in Belfast for a while).
Maybe another day.
Should be going for another 2 or 3 week vacation again though in 2010. Looking forward to it!!!
I’m envious!!
STROW :
Date: December 30, 2009 @ 9:14 pm
Hi Dennisb
I have toyota camry 1997. The heater works well while it is in parking or riding in less than 25mph. If i drive above 30mph I stop feeling any heat coming from the heater. It is also related with the temp gauge.The gauge indicates operating temperature (almost in the middle of cold and hot) while the car is in parking or idle. It drops to cold while i am driving above 50mph and then the car starts freezing. The air blowing from the heater gets cold. I have checked the coolant and it is on the right level. Can you please tell me what the problem might be?
Chris :
Date: January 9, 2010 @ 10:14 am
Hi Dennisb, I have a 2001 Ford F150 Supercrew. My heater will blow warm air for about 20 seconds then gets progressively cooler. I recently had the radiator system flushed and when I check, both sides of the heater hoses are hot…when I switch the heater on I can hear a faint clicking around the heater core behind the glove box. All fuses are good too. Any advice…?Freezing in Florida @ 20 degreees.
Thanks!
dennisb - Auto Tool Sales :
Date: January 9, 2010 @ 12:12 pm
Chris, It’s possible there is a problem with the heater blend door or actuator. The blend door in that model has been known to break. First though I would check to make sure it’s not just a plugged heater core – it can still feel warm on both inlet and outlet but not have enough flow. Since you say it does blow warm for a few seconds, that indicates that the air-flow may be correct, maybe just not enough water-flow through the heater core. I would try spraying water through the core with both hoses off to make sure there is PLENTY of flow (not just a tiny stream).
marty :
Date: January 9, 2010 @ 8:01 pm
hey Dennis my wifes toyota 2004 camry’s heater will run you out if its moving but as soon as you stop it blows cold air fluid is good both hoses are hot ect..
any tips ?
Thanks
dennisb - Auto Tool Sales :
Date: January 9, 2010 @ 8:31 pm
Marty, nothing comes to mind except the usual – low coolant or air in the system. You may want to ask a Toyota tech to see if there is a common problem – visit our ask a question page.
STROW :
Date: January 10, 2010 @ 4:52 pm
Hi Dennisb
I have toyota camry 1997. The heater works well while it is in parking or riding in less than 25mph. If i drive above 30mph I stop feeling any heat coming from the heater. It is also related with the temp gauge.The gauge indicates operating temperature (almost in the middle of cold and hot) while the car is in parking or idle. It drops to cold while i am driving above 50mph and then the car starts freezing. The air blowing from the heater gets cold. I have checked the coolant and it is on the right level. Can you please tell me what the problem might be?
yonathan :
Date: January 10, 2010 @ 9:00 pm
hey
I have same problem as strow. my 97 toyota camry’s heat works good on idle, and gets cooler when i drive (only in cold weather.) my engine must be extremely well cooled, cuz it will warm up idling, then i take off and watch the temp gauge go down! Thermostat has been changed but didn’t help. Coolant is full on the reservoir too. Please any tips ?
yonathan :
Date: January 10, 2010 @ 9:02 pm
………….coolant is to the level “full” on reservoir actually.
Garth :
Date: January 11, 2010 @ 3:22 am
Hey Dennis,
I have a peugeot 307 TDi 2003, and in 45 deg C Australian heat, air conditioning is a must.
The problem is when turned on, the AC only blows cold air from one of the central vents, while all the other vents blow hot air. I have tried all the different settings and can’t seem to fix this. Any ideas? Cheers
dennisb :
Date: January 11, 2010 @ 11:38 am
As far as the Toyota only heating well at slow speeds or idle, there could be a problem with the thermostat staying open. Sounds like the coolant is continually circulating and never allowed to heat up until the car stops and has less airflow across the radiator and also the pump is turning less revolutions. The t-stat should help to maintain normal operating temperature – and warm enough coolant to operate the heater.
If the heat only works while going at higher speeds I would suspect a partially restricted heater core (or low coolant).
dennisb :
Date: January 11, 2010 @ 11:43 am
Garth,
Wish you could send some of that heat to the states (45C = 113F).
My guess would be that there is an issue with one of the actuators (controlled by vacuum or voltage) which operates a door. I’m not familiar with your model, but that is where I would be looking.
josh b :
Date: January 13, 2010 @ 6:44 pm
I need some help. i have a 2005 chrysler pacifica 3.5L, AWD, last night my heater in the car stopped working. the front doesnt blow out any air at all and the back only blows out cold air. i checked the fuses, relays and it has plenty of coolant. Any suggestions??
dennisb - Auto Tool Sales :
Date: January 13, 2010 @ 9:36 pm
Josh, two different problems more than likely. NO AIR blowing at all in the front could be a front blower motor or poor connection to it. The front blower motor is located under the dash on the passenger side behind the glove box.
The rear problem could be a door actuator or plugged heater core. Checking a repair manual to understand how the rear system is comprised would be necessary for me to make a better guess.
I hope it warms up soon!
lou norris :
Date: January 14, 2010 @ 12:16 pm
Will removing the thermostat from my 1999 dodge caravan 3.3 auto, cause the heater not to work? When van is sitting for a little while idling and the temp. go’s up a little bit then the heater will blow warm air, but when you start driving down the road and temp. drops to normal it blows cool air.. whats up with that??
dennisb - Auto Tool Sales :
Date: January 14, 2010 @ 12:24 pm
Lou, yes removing the thermostat can affect the heater performance. It can also cause other problems like a fault code for the engine not reaching operating temp. fast enough.
Gilbert M :
Date: January 14, 2010 @ 3:26 pm
Dennis, I have a ‘96 Suburban that I think has low heater air temp. The maximum it puts out is 100F on low fan speed. At higher fan speeds the output temp drops to 80F. What should I expect for a normal air temp output?
dennisb :
Date: January 14, 2010 @ 7:31 pm
Gilbert, the maximum vent temperature should maintain around 100 degrees on max (recirculate) setting. The heater air temp should be checked after the the engine reaches normal operating temperature. Ambient/outside temperature can affect the car’s heater performance.
My car right now with 72 degress outside temperature has a maximum vent temp of 110 degrees with little change on different blower speeds.
On max setting, eighty degrees seems too low no matter what the outside temperature is. Any number of things could cause under par performance. One of the most common causes (besides low coolant) can be a slightly restricted heater core – that’s where I would be looking after ruling out easiest things first.
joe cartee :
Date: January 30, 2010 @ 8:29 pm
My son has a 1998 F150, We replaced the radiator because of a leak. We have no heat. Both hoses at the heater core are cold. We removed the top hose at the thermostat and the water continues to flow. Maybe the thermostat is stuck open ?
Sam :
Date: February 1, 2010 @ 6:59 pm
I have a 92 acura legend. I have problem of getting heat when engine is cold. I have to drive like 5 min before heat would suddenly would come on. Then one cold morning, I had the engine blowing coolant into the reservoir and spliting antifreeze out with engine temp way up high. I decided to change my thermostate and radiator cap and bleed air from the system via bleeding valve and the car was working fine for about two months with heat coming on nicely although I seemed to smell some sweet smell of coolant from the heater when I start the car and the smell would quickly goes away. As the time goes by, it seemed like my heater getting worst of each day and suddenly I have a repeat of what happened two months ago with my heater not coming on until 5 min later and then my engine is blowing hot air into my resevoir and temp way up high. I wonder why all this air built up in the cooling system and what is the root problem?
dennisb - Auto Tool Sales :
Date: February 2, 2010 @ 7:20 am
Sam, I would pressure test the the coolings ystem and do a carbon test to see if there is exhaust in the cooling system.
1. A coolant leak in the engine’s cooling system could allow coolant out and air in.
2. Exhaust in the cooling system (carbon test to determine) could mean a leaking head gasket which would cause air (exhaust) into the cooling system.
Either scenario could be the problem with repeated cases of an air-lock in the cooling system.
Dan :
Date: February 2, 2010 @ 12:46 pm
my car is a ford fiesta zetec 1999 and the for past two days the heater has been blowing cold air. i have checked my collant all hoses are warm and the engine is running at correct temperature. what could be the problem ?
Mike :
Date: February 4, 2010 @ 11:04 pm
2002 Pontiac Montana blows hot air then cold air. Eventually it starts blowing hot again. What would cause this to happen?
Rena :
Date: February 8, 2010 @ 7:19 pm
I have a 2003 Hyundai Santa Fe v6 (3L). The heat works at first but after using the heat for 45-60 min’s it starts blowing cooler. Any ideas on what to look for or where to start would be appreciated. Thanks!
Adam :
Date: February 14, 2010 @ 5:12 pm
I have a 2003 chevy s10, the heat is giving me some problems. I changed the thermostat and drained and replaced coolent. It takes a really long time to get any warm air out of it and then turns cold once I start driving. Any ideas would be helpful. Thanks
Matt :
Date: February 16, 2010 @ 5:05 pm
I have a 99′ ford Mustang, and when I turn the heater on, it will blow out warm air at first but then turn ice cold. I replaced the thermostat and filled the coolant, but it did not fix the problem. I am hoping that the heater core does not need replaced. Just wondering if you had any idea’s on what it could be.
Leah :
Date: February 17, 2010 @ 10:16 pm
I have a 2001 Toyota Camry and a few months ago the air stopped blowing out of the vent on the 2 lowest settings, but would work only when the gas pedal was pushed. Eventually that stopped working. Now air only blows out when it is on the highest setting, heat or a/c. What is the problem? How much to fix it?? Thanks!
Alicia :
Date: February 18, 2010 @ 2:14 am
I have a 93 Dodge Grand Caravan and I had to actually test a theory on it before I could start asking around about the problem. When I use the heat it seems to barely work. I went out to the store late in the evening and realized that as I hit 30mph the heat kicked on real strong but as soon as I would go below 30mph the heat turned to cool air, as if I had just switched on the AC. What could this problem be and how much would it cost to fix this?? Thank you in advance!
Jackie :
Date: March 4, 2010 @ 6:09 pm
How much should I be charged to replace the heater core in my 2005 Sebring and does the dash board need to come off to do so?
jason :
Date: March 7, 2010 @ 8:38 pm
I have a 1993 geo storm the heat works when i sit and leave it running but once i start driving it the temp gauge goes all the way down and blows cold air
Ron :
Date: March 18, 2010 @ 8:25 am
I have a 96 chrysler concord it will start blowing cold air then over heat. I have replaced water pump radiator and several thermas stats. any idea why this keeps happening ?
dennisb - Auto Tool Sales :
Date: March 18, 2010 @ 8:36 am
I apologize for not having the time to help with every question asked here. For more specific information and help with your heater problems I recommend asking your question on our Car Repair Questions section linked at the top of this page. There you can usually get help from a dealer tech that specializes in your vehicle make and model. Techs are standing by to address your problems at any given time of day or week.