A/C Compressor clutch not engaging

Hi Joe,

Thanks for the reply to my question. I picked up the car today. The dealership gave me a quote to replace the compressor and the dryer. When I took the car in yesterday and told the guy "the A/C isn't working and the compressor clutch isn't kicking in", he immediately said, "Sounds like you need a new compressor." So, I think he already knew what he was hoping to sell me.

I checked static pressure again after letting the car sit for a couple of hours in my driveway. 82 psig at 86 deg. F. Ambient.

I purchased a cheap code reader at Walmart. Started the car, plugged it in... No codes read. Turned on the A/C... No codes read. Scrolled down and found "A/C Refrig Mon N/A".

Any thoughts on what I should do next will be appreciated.

-Jim

I checked the fuses in the box under the hood. All okay. I have to do some reading on how to check relays. I have not looked at the fuse box inside the car yet.

Attached is a picture of the diagram on the underside of the fuse box under the hood. I'm not familiar with some of the abbreviations there, so do you see anything that would be related to the AC system there? Or should I be looking at the fuse box inside the car located under and to the left of the steering wheel? Or both?

I'll get under the car to check for voltage and continuity at the compressor soon. I don't have a garage and we're supposed to get a good dose of rain tomorrow, so this activity may be delayed.

The engine is a 4-cylinder 2ZR-FE model. The climate control is manual.

Thanks again for your help.

There is continuity on the ground wire to the compressor. No power in the power wire to the compressor until the A/C is turned on, then there is 12 volts. The fan in the engine compartment started running as soon as I reconnected the wiring to the compressor. Does this mean there's no need to go any further to check fuses and relays?

Joe, this loss of AC happened a month or two ago. It's a spare car, so I've been tardy in doing anything about it. I'm remembering now that one day on a trip to town, as I was stopping the car at the end of our street before making a turn, just as I put my foot on the brakes, I heard a screeching sound. My thought at the time was that the noise was connected to the brakes. I thought at the time it sounded like brakes pads on wet metal. What I don't remember is if that was the same day the AC stopped blowing cold. If it was the same day, then it would have been about 10 minutes later that the AC stopped blowing cold. If that screeching sound was in fact the compressor locking up, could it have taken 10 minutes or so before the air started blowing hot? It seems to me if the compressor locks up, the air inside the cabin would start blowing hot almost immediately. I'm thinking I need to try to figure out a way to see if the clutch plate on the compressor will turn at all. What do you think?

Thanks,
Jim

On second thought, I guess it does make sense that if the compressor locks up it could take 10 or 15 minutes for the liquid refrigerant to entirely bleed through the metering device. I don't recall, but it makes sense now that I think more about it, that the cold air would have gradually warmed as the refrigerant pressures stabilized between high and low sides. Am I right? -Jim

Hi Joe,

As checked a couple days ago, the static pressure of the refrigerant was 82 psig at 86 deg. F. Ambient. From what I've read, that is well within the normal range.

When I turn on the A/C, I don't hear a clicking sound. The serpentine belt turns freely with no squeaking noises.

I've learned that a malfunctioning low-pressure switch can cause the clutch to not engage at all. In the engine compartment I found the high-pressure switch on the liquid line, but I do not see a low-pressure switch on the vapor side. I found the drier attached to the condenser coil and learned that it holds a desiccant bag. Isn't there supposed to be an accumulator on the suction side? If so, I don't see it in the engine compartment. Could the accumulator be on the passenger side of the firewall with a low-pressure switch coming off the accumulator? I've looked for this information online and haven't found it yet. Can you help me find the location of the low-pressure switch?

Thanks,
Jim

Hi Joe,

A neighbor told me yesterday about a local one-man shop that he's had good luck with a number of times and that this mechanic should have the diagnostic equipment needed. That said, I'm not ready to go to that step just yet.

I stumbled across some new information last night. It turns out that my car is equipped with a clutch less direct drive variable displacement compressor. So sorry for taking you on a wild goose chase trying to figure out why my phantom compressor clutch wouldn't engage. Now I know that the round plate on the front side of the compressor in my car is not a clutch, but a safety feature to disengage the compressor from the serpentine pulley in the event of a failure of the compressor. I was able to get a couple fingers on that round plate and it spins freely. I wasn't able to see any sort of mechanical connector between that round plate and the pulley, so I'm thinking it must be a shear pin(s) that were broken. I'm going to get the refrigerant removed so that I can remove the compressor myself, then take it apart to see if it in fact suffered a catastrophic failure. It will be fun for me to learn, and it may end up saving me a lot of money.

This project isn't a #1 priority for me, so it may be a while before I get this done. As soon as I have made some progress, I'll report back.

Regards,
Jim