07 Base 460

Heat set at 74 fine unless pulled over at a stop idling for a while, then blows cool air, move heat setting up to 80 and blows warm again.
It this a thermostat that needs replacing or could it possibly be the anti freeze level has gone down?
I have tried without success to get those push plugs out of the cover over the coolant overflow tank, I assume if that is below the low mark that
could be the reason for my heat problem?

 

deleted deleted

 

unibee, thank you for your reply but my question has to with heating and not A/C cooling

it is a heating problem, see my original post, and please take another shot at it if you would !

 

deleted deleted

 

If the anti freeze is low that's the obvious answer. It would not be the thermostat because if it was stuck open your engine would not get to operating temp especially in the winter and if it was stuck closed your engine would overheat. Get that cover off and check the level in the morning before you start the car. Sometimes when the system is low on refrigerant it can affect the heat output since the systems are tied together.

 

Time for a drain, fill, and burp. If the antifeeze level looks fine you definitely have air in the system. This can cause unexpected overheat, so be sure you drain and fill. When the engine is cold, park on a slight incline (or on a jack) just make sure to keep the heater as high as it will go when you refill so the fluid passes continually through the heater core.

If you don't want to drain and fill, jack the car up slightly and put it on stands in the front. Run the engine and heater on full blast with doors open. Run it until the air gets hot for a few mins (check temp gauge while doing this) and let the air leak out into the reservoir. Lower, and let idle for a few more mins with the heat running.check the coolant level. If it's gone down any, then add some more coolant and repeat until level filled and heat is consistent. My opinion, there's definitely air in the system.

 

so when you say check the anti freeze level you are referring to the plastic overflow tank hidden under the plastic cover with the plastic rivets?

 

Check that AND when the car is cool, pull off the cap on the radiator, and check/top off there.

 

to my knowledge, there is no traditional cap. Its just the cap on the reserve tank (reservior). When you do the steps I noted, leave the cap off and make sure to replace it before driving. Make some sharp turns, bumps, inclines, with that heater on full, with the windows open, that usually does the trick to force the air into the reservoir, and vent it from the closed part of the system.

 

This happened to me! The first winter season we replaced the coolant and burped the system. Worked fine for awhile, until this winter season. It did it again! Come to find out the valley plate is leaking coolant. It leaks and puts air bubbles in the system so the heater doesn't work properly. It's very expensive job but worth it in the sense that if left alone could damage other components.

 

valley plate ?

 

Its deep down in the engine. Photos attached of my car of where coolant should be and shouldn’t be (where its all crusty).

 

I had this problem for years and just topped of the anti freeze once or twice a year.