I recently had my radiator flushed and refilled on my 94 z-28. Before this service I had no problems with my heater. Since the service, nothing but cool air comes out of the vents.The engine temp is also lower than normal. Would this be a thermostat stuck open that could cause this? Thanks.

Probably a thermostat problem,since you said the temp is not going to the normal range.Could also be particles from the flushed out radiator could have clogged the heater core.If thats the case you can back flush the heater core and usually, That will clear out the debis from it.

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69 Camaro SS 350 4 speed
86 Monte Carlo SS

Thanks. I remember when I got it flushed, the guy that did it asked me if I had had any problems with it overheating. I told him I had no problems. He said when he got through with it, the temp gauge went to around 225 so he cut the car off. Since that happened it has not overheated, but I have this current problem of no heat and not running at normal temp. I just wonder if they did something to cause this problem. I guess I will have to check things and make sure there is nothing unusual under the hood. Does the 94 have a heater control valve?

I don't think it has a control valve.Check your heater hoses to be sure.

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69 Camaro SS 350 4 speed
86 Monte Carlo SS

Start with the basics, make sure all the air is out of the system. Warm the car up and keep squeezing the hoses. This will do it

Trapped air and a bad radiator cap are possibilities

You have air trapped in the system. The guy who flusshed the system probably put the rad cap back on before the thermostat was open.

Just courious.If theres trapped air in the system wouldn't the engine run hot? I haven't worked on many late model GMs.Im a line mechanic at a Ford dealer,and any time theres air in one of them It's gonna get hot real fast..

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69 Camaro SS 350 4 speed
86 Monte Carlo SS

Gene The air thats trapped is in the heater core, not the engine.If the rad cap is weak there wont be enough pressure to force the water into the core

Thanks for all the help. What is the best method for getting the air out. I tried squeezing the hoses but it didnt seem to help. I may not have squeezed long enough to do any good. I thought I would see if there may be another way. Thanks again to everyone who replies.

the newer Camaros have a few bleeder valves scattered about on the engine to get tha air out. just loosen them up, and fill until water comes out. tighten them back up, and you should be good. just watch the temp gauge when you re-start it, inb case you missed one.

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1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16X8" IROC wheels. 12" Corvette brakes on the way.
see pics here http://community.webshots.com/user/novaderrik

Thanks. I put in a new thermostat and a new cap. The old thermostat was stuck open. This seems to have done the trick. The heater is blowing warm air now. Thanks for all the help. I learn something new all the time here.