No Heat

With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If not too hot to hold, then you have to look at the actual engine temp and if that is up, if it is, then your looking at a restricted heater core or poor circulation for another reason.
If you find that they are both too hot to hold, then the heat in that vehicle is controlled by a blend door that regulates heated air flow. it is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.

I took it in to a mechanic. they tried replacing the thermostat but that did nothing. They checked the actuator but it was fine. they flushed the heater core again. All of the dials to control heat and fan speed were also fine. The car is not overheating at all but it is still only blowing out cold air.

they suggested to replace an auxiliary pump(water pump?) but that was all the mechanic could come up with. Could it be the water pump, even if it is not leaking?
thank-you

When I warm it up it blows no heat slowly heats up to red on temp gage fans kick in temp goes down fans off temp goes up.still no heat.when you drive it temp is fine and you start to get heat

Okay, sounds as if you could just be low on coolant. When the engine is completely cold remove the radiator cap. Fill the radiator if it is now full. Start the car and let it reach normal operating temperature. Turn on the heat in the car. I believe on this motor there is a bleeder screw that needs to be opened to help relieve the air out of the system. Carefully open the bleeder screw until a solid flow of coolant comes out. You will most likely need to raise the rpm a few times while the bleeder is open to get the air out. confirm that you have heat at idle and the engine is not overheating at all during this procedure.

Ok I have no heat whatsoever.Let Me tell you this first my car overheated and I had a hell of a time trying to figure it out I changed everything, radiator, temp switch,water pump,thermostat, hoses,flushed the entire system. Along with flushing the heater core. Anyways after doing all that the car was still overheating so I found out that the last thing was that it was a head gasket. I did not change this since the car is so old and miles are high. So I bought some blue devil gasket sealer. And flushed it like it says bam. Works no over heating. But their is no heat in the car only blowing cold air. Iv read about checking the heater door actuator,I see that on the drivers side the actuator is moving same with the passenger side is moving also. So I was thinking that it might not be that cause it seems to be ok. My blower motor is new also and is working fine. I read about a heater control valve I cannot find that or is their one on the buick rendezvous? I am totally stumped any ideas I would really help.

check to see if both heater hoses are hot if they are check the blend door actuator. Here is a guide to help you fix the problem

https://www.2carpros.com/articles/car-heater-not-working

and

https://www.2carpros.com/articles/replace-blend-door-motor

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

I had this problem and had to replace the thermostat cost me $34.00 all fixed! I love this site, the guides are great!

I have a 2003 Buick Rendezvous, The heater fans worked all day yesturday. After work I went to start my vehicle and the blower fans no longer worked. I checked the fuses and none were bad. What could this mean?

I'd want to get at the blower motor connector, take it loose. Key on, hvac on, use a voltmeter on the wiring harness connector, anything? Red wire is voltage, black is ground. If you have good voltage and ground with no blower action, suspect the blower motor. There is a hvac ignition fuse, goes hot with key on. Check for voltage on that circuit, even if the fuse is good, if there is no voltage the circuit is dead.

Heater problem
2003 Buick Rendezvous Engine Size unknown All Wheel Drive Automatic 76000 miles
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My heater only works when hitting the gas and only when on one setting. When I pick the setting that blows the heat from the dash board directly at you, it works, when I pick the floor heater or defrost, it just blows cold air. I know nothing about cars... would like some insight before heading to a garage. Thanks.

defrost wil do that, it usue the A/C, If you select floor/defrost Im not sure if you will get any hot air.Have the heater core flushed, I have seen amny of them get plugged so that it takes a hard flow to get hot water into it

Heater problem
2002 Buick Rendezvous All Wheel Drive Automatic 86000 miles

Not all the time, but 90% of the time, my heater blows cold air when it is set on high.
My blower is strong, my car is running for more than 30 minutes, but it's still cold air.
I have also noticed that when my heater is blowing cold air, my engine thermometer is to the 3/4 mark some of the times.
If I need to replace the heater thermostat, how do I find/do that?

UPDATE!! Several hours after I posted this message, my car "overheated" within 3 miles of leaving work. All my fluids were full, clean and after I let the car sit for 30 minutes, I was able to drive it home all while the temperature gauge fluctuated rapidly from cool to hot.
The shop found that both gaskets on my intake manifold were leaking. This is a common problem in this year of GM engines and they won't do anything about it even though they are very aware.
One of the leaking gaskets was very close to my temperature gauge and as the coolant shot out sparatically, this would cause my temperature gauge to fluctuate from hot to cold, causing my car to think it was overheating. If you have a GM engine model ranging from 2000 to 2004, check for these major problems.

You may possibly be low on water. If so, the heater core is empty and therefore, blows cold air. This could also explain the higher engine temps. Check the coolant level first! If it's ok, we'll start checking the operation of the heater and controls, such as the blend door motors, electronics, etc...

I have the same issue, how do you check the Blend Door motors?

The car drives for all of ten minutes then overheats. There is no heat inside the car. I changed the thermostat, added coolant and did the bleeding things. What could be the problem?

no heat is usually a sign of no/low coolant. have the car pressure checked you may have a head gasket leak. also, try an actuator reset by pulling heater fuse for sixty seconds with key on then reinstall it may reset.

Will resetting or pulling the heating fuse for sixty seconds help the overheating problem too?

Will resetting or pulling the heating fuse for 60seconds help the overheating problem too?

the fuse pulling will NOT help the overheat problem have it pressure checked for leaks which may tell of a head gasket leak if no external leaks.

2002 Buick Rendezvous CXL over heated. I broke down a couple months ago from bearings in AC compressor going bad. The mechanic somehow fixed it with keeping same compressor in but ever since he fixed it, there's no heat. Sometimes it will blow warm air but then stops soon after and blows cold air. Have also noticed temp rises to over half when we start it and let it warm up for about 30 min. Today I let it warm up even longer hoping to have some heat, but when I got in to leave, temp gauge was all the way up and over heating. Not sure if it's just a coincidence but never had any of these problems until the mechanic somehow fixed the old AC compressor. Please help.

check coolant level first if low have system pressure checked for leaks. like ahead gasket. your air temp actutator may not be working so pull hvac fuse for 60 seconds with key on then reinstall. some times they reset if not see if actuator is getting power or not.

I also checked the radiator hoses the upper one is hot and the lower one is cold. There us no water flowing through. Is that normal?

this can happen if fluid is low check coolant level and add 50/50 mix of antifreeze until coolant bottle is at full mark it may take a few minutes and be careful if you hear it boiling like a coffe pot do not open as you can get burned

Just check the coolant level there wasn't enough in there so I added some. I started it up and thick smoke was coming from the tail pipe and smoke coming from the top of the engine. What problem could that be?

Forgot to say I added 50/50 Dexcool coolant.

had an overheat and could not find anything obvious, so I changed the thermostat and flushed cooling system. Thermostat was a project. It was ok for first 5 starts approx 100 miles then same condition start cold and temp keeps going up, then There is no heat from heater. Noticed bubblescoming up into coolant res tank. Help

The bubbling could be from it boiling. Have you checked to make sure there is no coolant getting into the motor oil?

Let me know.

Joe

if you are getting smoke out the tail pipe then you have a head gasket problem and will empty out your coolant very quickly coming out on top can be leaking from anywhere.. cracked hose , gasket etc.

Is that an expensive problem or can blue devil fix it?

blue devil won't fix it and it's around $1500 or so but check locally prices vary

The temp gauge is normal. Heat blows while moving but not sitting still (cool air blows when stationary). The blower works in all positions. Coolant level is good. Seems to be the same regardless of defrost/dash/floor.

Inspect the air blend door/actuator

Hi most likely a vacum problem . the heater controls are either controlled by vacum or elec over vacum. you have more vacum being produced at higher rpms then at idle. most likely one of the vacum lines at your heater switch or in the heater box at the blend door. prob not off but loose and leaking vacum.


possibly a bad heater control valve this is under your hood inline on your heater core hoses. Thanks for asking..Billymac

Ive had this problem with my heater for almost 2 months now. When you are at a stand still, or start to slow down at all, it feel like the air conditioner is on. It blows out freezing cold air. Then, when you accellerate and reach about 30mph, it blows out warm air.It isnt hot by any means, but it warm. I am thinking maybe the thermostat is stuck open or something. I thought about getting a radiator flush, but I cant really smell any antifreeze or see any leaking on the floor. So, Im not thinking that it is the heater core. Im not sure. Any suggestions for me?

Is the coolant level full? Is the engine running at a normal operating tem.

Let me know.
Joe

replaced head gaskets, intake gaskets, new radiator, new thermostat, new heater core, new antifreeze, changed the oil and filter

try pulling hvac fuse inside car with key on for 60 seconds the actuators may reset and you'll get heat . I f not the actuator may be bad.

My heat does not work on the passenger side only, it just blows cold air. The driver side works fine but no matter what I put the temperature at the passenger side never gets warm.

sounds like one of your blend doors inside of the dash is hanging up and not moving or the electric motor has went out. your with air off turn the switch and see if you can hear the blend door moving inside the dash. listen for change of airflow or anything.

The heat in the cabin runs cool. It blows in fine however it just does not get very warm. I have not changed the coolant fluid in the car and was told that the fluid is very dark, but t is full. Could this be the reason why the heat in the cabin is blowing cool ORcould it be the thermostat or heater coil. Someone please advise. Thank you!