Cesar F

Hello all. First time on the board and I am looking for some assistance on (the only) problem I have had with my 2004 Mazda3s 5 door. In a nutshell, the car blows cold air at idle even after the engine is warmed up. Living in New England, that means that when you start your car to warm it up, it will always blow cold air until you begin driving, no matter how long the car has been running.

At 1700 RPM's or above, the heat blows normally but when you stop in traffic or at a traffic light, it simply blows cold air again. I have had Mazda look at it and they said it may be a blown head gasket ( a tiny head gasket leak) but when a test was done running 170lbs of air through each sealed cylinder, no bubbles were observed in the coolant recovery tank. Also, I haven't noticed any coolant los or white smoke typically associated with a head gasket problem.

I hear air gurgling through the HVAC system when I am driving and I have had the cooling system "burped" three times to remove any air pockets if that matters.

The car was in an accident before I bought it, and I am cool with that and all since it was fully disclosed, and it now has 44K miles on it.

I do know that the water pump was replaced, or I was told it was, and I have had every hose checked and rechecked as well as a new thermostat. Also, and very important, the engine does not overheat or even run hot. The gauge is where it is supposed to be.

Any ideas, fellas?

Cesar F

UPDATE:

First of all, the car still does not have any heat at idle. The following was done by the selling dealer:
Flushed heater core, said that it was normal.
Removed water pump and found impeller (SP?) to be fine. Said it was recently replaced.
Replaced ATC to insure that temp gauge is showing proper temp.
Replaced or inspected all hoses (4 are new).
Bled the coolant system.
The antifreeze level remains constant in the recovery tank.

Any ideas?