Intermittent A/C 1994 Toyota Corolla

Question

Symptoms

1. Refrigerant is not low. I repeat - refrigerant is not low.

2. A/C is not "freezing" up.

3. A/C works every morning. Turn off A/C or stop and get gas after engine is running for 5 minutes and hit or miss if A/C will turn back on.

4. On hot afternoon A/C may not blow cold. Turning on A/C will result in "click" from what I can only assume is A/C clutch engaging and engine sounds as if there is slight strain put on it, however, A/C tube is NOT cold.

5. Let the car cool down and crank up several hours later at 11PM and A/C runs like a champ. A/C tube checked earlier is now cold.

I was thinking this was the A/C relay but I hear that standard "click" and slight strain put on engine even when A/C is not working so ..... second guessing myself now. A constant given is A/C will work on warm days. On very hot days or if A/C is turned off after driven a few miles A/C may not turn back on until evening. No issues that I am aware of with dash electrical - again - turn on AC and "click" with slight engine strain though A/C tube not cold.

What is the scenario where clutch engages but tube is not cold (until you let engine rest and crank up at 11PM and all is fine)?

Answer 1

Refrigerant was only topped off due to original issue. I found a very similar thread on another site describing almost the exact same thing (though not intermittent) with drop in RPM when A/C is turned on (but no cold A/C tube) where problem was resolved with relay.

I blew out A/C fan blower relay and A/C MG relay along with seats with contact cleaner and swapped. If issue is resolved I am done; on off chance that blower stops working in future I will buy a new relay. If same issue persists (A/C stops working on hot days with swapped relay) I will replace swapped 25year old relay but not hold my breath that issue is resolved.