Soku1kcivic

Hi, I have a 95 Honda Civic Ex (completely stock) I notice my a/c would stop working when temperature gets up pretty high and has been happening a lot lately, so I finally check it out.

I was driving to my office when it was 103F outside and my a/c was blowing cold air with a thermometer on my vent showing around 47F and when it stop working it rise up to about 90F from the vent while sitting in traffic (no load) my idle was 1500rpm. I guess cause there is no load from the compressor to compensate it. This was about 15min without the compressor engaging. I pulled over while the car was idling at 1500 pop the hood notice the compressor not engaging and condenser fan running. Got to work and left it. So when I started to drive home from work It was still 100F outside so A/C did not work, but when I head home where it was around 85-90F my compressor kicked in (I left the A/C on even it didnt work) It kicked in cause my vent thermometer is coming close to 50F. By the time I got home I checked it out.

Outside temp was 80F at my house humidity was about 40%
Did the performance test from Helms manual with some gauges.
I got:
30psi-low side at idle (800rpm)
225psi-high side at idle (800rpm)
vent temp was (45F)

So based off the chart on page 22-19 my a/c seems to be with inspect.
Chart shows
at 80F with humidity at 40% about
27psi-low
270psi-high

When system is off low side and high side are 100psi equal

So I proceed to troubleshooting on page 22-6 for compressor clutch not engaging
I preformed all flow chart and it is telling me its my a/c pressure switch. So I am wondering if I should replace this? Because my A/C works great around 80-90F and cycles normal meaning (compressor goes on and turns off for 5 secs and goes on for a few minutes) but compressor wont engage when its higher than those temp outside. I will inspect my clearance, thermal protector and field coil tomorrow.

Could it also be my ECU/ECM?

I hope an A/C expert would give me some guidance to this problem.

Thank You.

Ryan Lwin

Hey, I had this problem before in my car. But in my case, it was the red wire that is connected to the electromagnet on top of the compressor. The connector was loose. Exact thing happened to me while I was driving on freeway at that time. My fan was running, but my compressor wasn't engaging. Then, when I almost got home, it started running again. I may have drove over some bumps and it caused to loose. I got home and found the problem. The connector was loose. So I cleaned it and made sure the connection is tight. And it didn't happen anymore. Of course, I found this problem because I was inspecting the compressor clutch and it's wiring and started tracing the wire. The red wire that is connect turns on when you turn on the A/C switch supplying 12V. It is located between the A/C fan and right headlight.

If that is not the problem, I suggest you trace the problem from A/C clutch and around. Check the belt, check that wire.

Your pressure of the system is ok. So it can't be because of the low pressure. And thanks for providing every possible info.

Former User

When it's hot and the clutch won't engage, unplug the pressure switch and briefly jump the 2P connector with a paperclip to see whether the clutch engages and the A/C blows cold.

Soku1kcivic

I will check the red wire tomorrow when I do the clutch clearance.

@Ron- I will check that tomorrow when it gets hot outside. I have an old condenser in my back yard with another pressure switch. I removed it looks like freon will escape out if I removed the switch. Is there a way to replace the switch without letting the freon escape? Looks like the switch in the Civic does not have valves to retain the freon.

Ryan Lwin

Does it drip out or is it pressurized? If it's dripping out when you take it out, it's ok. Just catch it with a cup or something.

Former User

Do troubleshooting tests to pinpoint the problem before contemplating replacing any parts.

Soku1kcivic

Totally agree with you Ron. It defeats the purpose of troubleshooting and saving money. Really appreciate your help. I will get back to you later this evening on some new test.

MugenGTR

Could just be the clutch is worn out, that is why it is only happening when it's super hot.

Soku1kcivic

So I replicate the problem again. A/C was working great until i drove around for about 20min. The compressor was not engaging I pulled over my idle was at 1500rpm. I unplugged the pressure switch and jumped it to see it would turn on. It didn't and my condenser fan was still running, so I plugged it back into the switch still not engaging. I got in my car and drove about 40ft from where I was the clutch engaged and a/c started working again. So iam wondering if its the compressor or my ECU, but I am going to check my wiring harness for any opening or loose connection. The compressor relay was fine when I was troubleshooting and testing yesterday. I havent checked out the clutch clearance and coil and thermal. I will do that when I get out of work.

Former User

A faulty pressure switch is now ruled out.

Test the compressor thermal protector, as suggested in post #2. Again, the test must be done when the clutch won't engage.

Measure the clutch clearance as well.

Heisenberg

Hey man, did you ever fixed this issue? I have the same exact issue, except that I discovered it is coinciding with a bad voltage regulator which causes battery voltage to go up (beyond 14.4V) when the A/C clutch disengage and RPM rises. Maybe those are totally unrelated, but you might want to check battery voltage too.

With that said and putting that out of the equation, one thing I haven't checked is if there is voltage on the A/C clutch relay coil when the clutch disengages. We know it's working, but maybe intermittently and is affected by heat. If there is voltage, then there should also be battery voltage between the red wire and body ground of the compressor. If none, could be bad relay contacts. Or it may be that the red wire's resistance gets too high during extreme heat and is unable to power the clutch. Same thing with the ground (body), could be very poor when engine bay is hot.

I hope you have fixed this pain in the ***.