eightmin

My wife's 2005 Impala (3.8 liter) ) has had a low or insufficient heat issue for a while now. I have changed the thermostat 3 times. There are no coolant leaks, coolant is full and the intakes are not leaking. Coolant looked good and tested to -25 deg. but I flushed and refilled anyway. As best as I can tell, the blend doors are working. I can only see the passenger side (dual temp controls) controller. It moves what seems like a 1/4 turn from full cold to full hot. This problem started towards the end of last winter. It got really warm here so I decided to wait until the temp started to drop so to make it easier to find problem.
The lights on the temperature control unit are both out (pass and driver side). I am wondering if this is a controller issue. Want to test as much as I can before I head off and get raped by the dealership first. Anybody have any ideas?

tech2

does the engine coolant temp gauge come up to 80 to 100*C. Are the heater core lines hot at this time.

eightmin

Sorry I did not respond right away. Did not have a chance to work on the car until this weekend. The temp. gauge goes to about 185 dg. (85 Celsius). This seems a little on the low side as every GM car I have ever owned seems to run at about 200 degrees on the dash gauge (93 Celsius) when at full temperature. I have bled the air out several times. I have disconnected the heater hoses and ran water through the heater core with a garden hose to make sure the core was not plugged. Water flowed freely. This morning I pulled the t-stat and put it in boiling water to make sure it opens and closes, and it does that fine. The lower radiator hose I just noticed, never gets hot. I am now thinking I may still have an air pocket somewhere unless you have another thought.

tech2

the problem is either a coolant temperature problem or temp blend door problem.
if you answer my questions, i can guide you to a fix.

when the car is up to temperature; are the heater core inlet and outlet hoses hot to touch. a normally system when up to temp, you should not be able to hold these hoses for a long time. if it is hot. there is an air flow problem through the core (you have verified coolant flow) or temp blend door not moving to the full hot position.

eightmin

I found the problem, I had an air pocket. I did not replace anything or make any repairs of any kind. I now have heat. Thanks for your help.


To recap what I did since I last posted, in case someone else follows this thread later: I had pulled the heater hoses where they connect to the water pump and ran water through the heater core to check for blockage, no blockage, water ran freely, came out clean. I pulled the t-stat out and checked it on a stove in hot water to make sure it opened and closed properly, it was fine. I put everything back together and again, bled the system. This time when I bled it, I could hear tons of air coming out of the bleeder. It took several minutes to clear out and get coolant at the bleeder. I'm just guessing but what I think may have happened is that somehow, opening up the system and then re-bleeding may have somehow moved the air pocket allowing the system to bleed completely. I have no other explanation. I did nothing else other than what I wrote and I bled the system the way I always have bled it.


This is how I bleed the system: Let the car get cold, open radiator cap to top off coolant, put cap back on and then top off overflow tank. Crack open bleeder on top of t-stat housing and start car with heat set to full hot. Let car get to full operating temperature (goose throttle to run at high idle occasionally) and wait for air to stop hissing out of bleeder. When coolant comes out without air, close bleeder, shut car and let cool. Top off coolant after engine cools and then recheck for air by repeating procedure.


Sometimes cars do things that just make you say...huh?