Got an 01 accord EX. Had it since new.

A/C will blow 45 degree air for about an hour, then air temp will warm up consdiserably. If you shut the car off, and wait about another hour or so, it will repeat the same thing - cold air for an hour, then it warms up. Airflow volume is fine. Obviously the compressor is working, and freon is not low. Belt is not loose either.

Any ideas on simple things to check? Already replaced both a/c filters - that had no effect.

 

When you turn on the a/c with the engine running do both fans on the radiator turn on?

When the a/c gets warm, is the compressor clutch still spinning with the pulley?

 

just tried it.
with the engine cold and AC turned on... both fans initially come on, as does the clutch spinning. then, about 10 seconds later, clutch stops and both fans stop

this repeats over and over

 

This will definitely take some diagnosis before identifying the problem.

Is this a 4-cylinder or v6?

You might need a volt meter to do some electrical testing. Are you good with using a volt meter? Or do you have an a/c manifold where you can measure the pressure in the a/c system?

The next simple test is to allow the car to warm up to normal operating temperature with the a/c turned off. Then turn on the a/c. Let us know if the fans and/or clutch cycle.

 

If you start getting "smoky fog" from vents when AC begins to blow warm, then evaporator freezeup is likely.

This can be caused by failure of the ac thermostat to open compressor clutch circuit when evap temp gets to about 30F. I've also heard that low refrigerant charge can cause this, but since you're getting 45F temps until problem arises, this seems less likely.

When AC stops cooling, does the compressor fail to engage? This suggests AC relay, ac clutch coil fault, or excessive ac clutch plate gap.

You need to determine what's happening when AC fails to cool. Does comrpessor fail to engage? 12V to clutch coil or not?

good luck

 

4 cyl engine
yes...familiar with volt/ohm meter
do not have manifold guages
no smoky fog from vents - ever
Drove car for 1hr and 30 minutes...worked like a champ. 40 degree air when we got home, but both fans and clutch still cycling off and on constantly. on for about 6 seconds, off for about 10 seconds - and this continues to repeat with 40 deg air coming out. Is this cycling normal??

Would probably have to drive it longer for issue to surface.

 

With 40 degree air out of vents, frequent cycling indicates the ac thermostat is protecting against evap freeze-up.

You will need to diagnose when AC fails to function correctly, checking compressor clutch connector for 12V.

good luck

 

not sure I understand. how can the clutch connector NOT be getting voltage if is obviously cycling on and off?

what would interrupt the voltage and make it intermittent?

 

You want to verify the clutch stops working due to loss of voltage. The PCM controls the compressor clutch relay and the fans when the engine is cold.

Your car has a basic diagnostic trouble code reader for the HVAC. Here is how to check for codes.

1. Turn ignition switch to ON (II position).
2. Turn blower fan switch off and re-circulation switch to ON (light turns on).
3. Press and hold the re-circuiation switch to fresh (light goes off). Continue to hold the switch until the recirculation indicator turns on for 2 seconds. Then it will blink diagnostic trouble codes.

After the two seconds of the light on, the light will turn off for two seconds. It will flash 1, 2, or 3 times, pause for a second, then keep repeating if there is a code.

Hope this makes sense.

 

Where exactly are these codes showing up?

I'm guessing I need some kind of tester to read them while performing the steps you laid out?