No heat, Buick Rendezvous.

dgoines1

I have a 2002 buick rendezvous  i have replaced the head gasket thermostat and coolant about 6 months ago i have no heat even after letting  it run for 20 min please help

imidazol97

dgoines1 said:

I have a 2002 buick rendezvous  i have replaced the head gasket thermostat and coolant about 6 months ago i have no heat even after letting  it run for 20 min please help

Is the radiator hot after idling that long?

1) Is the radiator itself full if it's a different cap than the reservoir tank? Do not open hot. If the reservoir tank cap says do not open hot, then you don't have a separate radiator cap. Sometimes the reservoirs can show full when the radiator has air in it, possible from a head gasket leak or intake manifold leak on certain engines.

Typically, you get bursts of heat when water is pushed through the heater core with low coolant level.

2: If you are comfortable working about running engine and know not to have loose clothing or to touch anything on the engine, reach where the heater hoses go into the firewall after the engine is running and hot. Have the blower inside the car on a fairly high speed. One hose should be slightly cooler than the other; the colder the air outside is the cooler the return hose will be. The heater has taken heat out of the water.

IF not comfortable with working around a running engine you can do the touch test immediately after shutting off the engine.

If one hose is a lot cooler, you may have a blocked heater core.

3) Your temperature blend motor on the heater case inside the car is not working. Motor dead or door is stuck.
If you are comfortable under the dash, you can remove the plastic panel and visually see the motors about the size of a pack of cigarettes. One for the temperature (blend) door, one for the mode door that changes the direction the air moves through the heater box. One for the passenger blend door if car has a separate temp system for the passenger.

I'll try to find a picture. Is the air coming out on the floor? Or coming out the windshield and is warm there but you're getting no flow onto the floor? That might be the mode door having failed.

ray80

Did you properly use the two bleed screws with vehicle on level ground and heat on full to get air out of system? Temp gauge in normal range when warmed up?

dgoines1

I put it in the shop and a gm tec did all the work

dgoines1

Thank you i think i have found the problem.  The mode door has failed i get good jeat if i just use the floor setting and none on any other setting. Thank you

imidazol97

imidazol97 said:

I'll try to find a picture. Is the air coming out on the floor? Or coming out the windshield and is warm there but you're getting no flow onto the floor? That might be the mode door having failed. The inner workings may not
be cooperating when the electric actuator tries to move them to pass the air to the dash vents or through the defroster.

http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=366294&ukey_make=1022&ukey_model=14450&modelYear=2002&ukey_category=19390

If you are automobile handy, and agile, the electric motors can be replaced fairly easily
for some of these. Access is the problem. The actuator motor just pull off the axle
that they rotate. rockauto.com is a good place to price replacements. They are available
in the aftermarket. You may find a good mechanic who can change it for you without
being killed financially on the part and labor at a GM dealer.

rockauto.com
The link I showed for the parts diagram also has pricing.