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'96 coupe. AC worked fine up to a week ago. Blows air, but war, not cold like before. Checked diagnostics, code 9, low refrigerant. Compressor clutch not activated, no signal at cluctch connector. clutch coil has continuity. Replaced relay, still NG. I have one of those R134 replacement cans with a pressure gauge, stuck it on the low side,( connection between evaporator & compressor), and it read way high. I think this is ok, as the pressure equalizes when the compressor isn't running?
As an aside, the controllers seem to operate correctly other than no cold air, cycled functions on controller, so I'm thinking the programmer is functioning ok.
Anyway I'm down to the 2 pressure switchs, which means its off to a repair shop, as I don't have real gauges , vac pump, etc.
Thought I run this by the A/C gurus here; Am I missing something obvious, or have I hit the right stuff?
The some of little recharge kits come with a low side gauge although not precise can give you an idea of state of charge. Of course if it's really low there's a leak. I would use refrigerant with dye to add or top off. Black light could be used to find leak. You would also want to check service valves much like a tire valve ...bubbles means it's leaking
Greetings. I've had success with automotive AC repair and consider myself well-read on the subject.
It seems like so far you've done all of the right things, and you're correct that pressure reads "too high" when the compressor doesn't run, which is actually a good sign and means there's probably still r134 in there.
Based on your results, it would seem your low side pressure switch is defective. Can you take a measurement of the pressure again and report back what it is...with one caveat, please also make note what the outdoor temperature is, that's important! Refrigerants rise in pressure as their temperature rises. At 75*f, the static pressure of r134 is 73psi. Once the compressor runs, the low side pressure (the only side one can measure without manifold gauges) will vary between 25 and 35 psi. Also, test for continuity on the pressure switch, which it should have if the pressure is higher than 45psi. If it doesn't, the switch is no good.
I hope this information helps you
Last edited by Circuit Doctor; Jul 2, 2016 at 10:14 PM.
Hey CD, thanks. I'll check the pressure at the low side, but it appeared to be around 100 psi, but it was on the little gauge attached to the refill can. Would you know if the '96 has a schraeder valve below the low side switch? Based on other AC threads, it sounds like earlier C4's did.
MIne failed on the '93 a couple years ago, I added the R134 with the dye, disconnected the battery and waited. Re-connected battery and started the car, the compressor runs a half a minute. Then, with UV light in the dark I tried hunting it down. No luck. Until my last peek, it was a low-pressure switch leaking on its underside btween the hex bolt and the plastic in the middle. Replaced the switch, vacuumed, re-charged, and all is well. A set of gauges is a must. Might as well do the orifice tube while in there, maybe put a new dryer in, they're cheap like $24 or so.
The schrader valve is part of the service ports where the gauges would attach to the car's A/C lines. They look very much like the valve from a bicycle tube, and are replaceable separately in most cases.
The schrader valve is part of the service ports where the gauges would attach to the car's A/C lines. They look very much like the valve from a bicycle tube, and are replaceable separately in most cases.
Kevova, I understand the 2 valves for measuring / charging the system, I was referencing a couple of older threads that seemed to indicate that there was another valve under the cycling switch, which would allow replacement without evacuating the system, and requiring a subsequent recharge.
Sorry I wasn't clear on that. But thanks for the help, I need it...
So, I put all the highly appreciated thoughts posted together, and I disconnected the battery neg terminal for 15 minutes to let any charge dissipate on caps..reconnected neg cable, started the car. Code 9 is gone, and the A/C works. I connected the recharge can that has a gauge of dubious fidelity, and it appears there's 45 PSI on the low side.
I have cold air blowing on the way to work today, so, so far, so good. I am wondering, however, what would have made the compressor cycle enough in 1 minute to trip the code 9.
Anyway, thanks to all who posted thoughts. I'm sure my co-workers are deeply appreciative that I didn't show up today all sweaty & stinky!
So, I put all the highly appreciated thoughts posted together, and I disconnected the battery neg terminal for 15 minutes to let any charge dissipate on caps..reconnected neg cable, started the car. Code 9 is gone, and the A/C works. I connected the recharge can that has a gauge of dubious fidelity, and it appears there's 45 PSI on the low side.
I have cold air blowing on the way to work today, so, so far, so good. I am wondering, however, what would have made the compressor cycle enough in 1 minute to trip the code 9.
Anyway, thanks to all who posted thoughts. I'm sure my co-workers are deeply appreciative that I didn't show up today all sweaty & stinky!
did you read step #1 on page 1c-17 of the FSM? this could have triggered the Code 9...
No A/C Cold air
