Okay, I am sure this is posted somewhere in the forum but after hours of looking, I haven't had any luck.

For the past week, my wife's 2004 GX A/C has been blowing hot air off and on. At first I thought this was due to low refrigerant but after pressure testing it appears to be full. Yesterday afternoon I was driving the car home and the A/C was blowing cool air then suddenly stopped again, I happened to look at the engine temperature gauge and noticed it creeping to "H". I shut down the air all together, pulled over and it cooled. The gauge actually stayed below the half way point the rest of the way home, until I had to stop at a light, then it slowly climbed up to the "H" again, the lowered as I drove to a cruising speed 55MPH. One home, I looked at the coolant reservoir and there was no fluid in it (not sure if this is normal) and there was no sign of smoke or fluid leaking. Could this be a thermostat issue, radiator issue, loss coolant issue???

 

Is it possible a piece of paper is blocking airflow to your radiator?

 

Unfortunately, there is nothing blocking the radiator, but thanks for the response. The other piece to add is the fan in front of the radiator is turning on when at idle, idle with the AC on. It did start turning a little yesterday, but shortly turned off. I haven't observed with the engine "hot".

 

Two problems may not be related. Do another search on a/c, Mann77 always points out that there is a relay that kicks the compressor in for a/c that seems to be an easy fix.

 

As Quoted about two Issues,
One being the Engine Temp going high - Probability areas are the Water Pump Leak, Radiatior Leak, Coolant Not holding up, Faulty Pressure Switch, May required to replace the Upper & Lower radiator Seal ( Very long job), leakage of compressor oil. Better if have a good AC mechanic get this job checked.

AC not cooling - For the start Check the Magnetic Clutch Relay within the Engine Fuse Box and replace only if the following has a different part one from the installed one your truck and if the AC light is flashing while the AC becomes on and when warm air is released you wud have the flashing lite. Then it means "Replace
Old P/N - 90987--02022"-
time to replace - 2 minutes
Cost of Part - $30
New Part Number - 90987--02028.

 

So, I switched out the Mag Clt switch to the updated model and the A/C is still flashing. I can turn off and on a few times, then it works for awhile and then it flashes again. I did read in other forums that you are to disconnect the battery before replacing. I missed this step. Thoughts????

 

Hi, I found your post regarding a/c engine overheat on your GX 470, I am having exactly the same problem, what was the solution?
Thank you,
Vadim

 

There's several things it can be. Check:

1. That the correct coolant was used. Never top-off with plain water.
2. Coolant level -- the overflow tank level should be at the "Cold" line when the engine is cold. Add pre-mix Toyota coolant to the tank (when the engine is cold) to bring it up to the "Cold" line. Check again over the next few days after having driven it. Check with your dealer to see which coolant you should buy - there's a couple that they sell and you shouldn't interchange them.
3. Bad water pump
4. Thermostat stuck closed

If the coolant level was low, it had to go somewhere as it's normally a sealed system. Look for a radiator leak (blue crystals around the edges). Look for drips from the water pump (time for a new one). Look at the oil condition (should not be milky). Look for white-ish smoke from the tail pipe.

Chip H.