Air Conditioner Not Blowing Cold Air

Reader Question

Hello Mr. Davis…

Long story short, my car’s a/c and heating does not work appropriately. These fixes can be pricey, so I do not want to pay for 9 wrong fixes when only the 10th is needed…

The facts:

(1) The blower works. Air does come in and can be circulated.

(2) When the temperature outside is hot, the a/c will not blow cold air. The air MIGHT be slightly cool, but only for a few minutes…before the engine heats up.

(3) When the temperature is cold outside, hot air will not blow inside the cabin… A mechanic did say that the blend-door (of the heater valve of the heater hose) was not opening/closing appropriately, and he tied the valve to the open position for winter. This enabled hot air to be blown inside the cabin with the heater on, but ONLY after the engine temp reached midway between H and C.

(4) The compressor does sound to be engaging appropriately.

What can explain all of this? I don’t mind paying for the fix, but I only want to pay to fix what is actually broken…

Thank you!


Hi there. First thing I would do is repair the heater valve problem first. You do not want hot coolant inside the dashboard with the A/C on, it will greatly diminish the cooling ability.

What you can do yourself is take a pair of vise grip pliers and clamp down on the heater hoses with the pliers to shut off the flow of coolant to the heater core.

This will not cause the engine to overheat (unless there is a restriction in the radiator) but will tell you if the heater valve is the culprit for the lack of cold air.

If you can block off both heater hoses and still don’t have cold air out the ducts, then I would suspect you might be low on Freon in the A/C system.

You should have a Freon filter (accumulator drier) located up near the radiator. Most Japanese driers have a “sight glass” on top of it that will show bubbles when the system is low on Freon.

The sight glass should be clear with no bubbles in the sight glass area if the system is full of Freon. Check the glass WITH the engine and compressor running.

Here is a picture of what that drier should look like, the sight glass is the round hole on the top between the two line connections.

Picture of A/C Drier

Another thing I would look at is the electric cooling fan motors up near the radiator. You probably have 2, one for the radiator and one for the a/c condenser. With the A/C compressor ON you should have 1 of those fans on and running.

Austin Davis

About the Author:

Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."
  • Austin Davis

    You might smell a little smoke for a few miles, due to oil spillage on the engine during the repair but I would expect it to burn off in a few miles.

  • Shavonne D.

    I just had my val cover gasket replaced should I smell smoke or oil? I want 2 know if some oil could have dripped on the gasket?