Good afternoon All,

The AC compressor clutch isn’t engaging. I swapped out the compressor clutch relay with several other relays without success, so I don’t think it’s the relay. The MG Clutch fuse is good, so it isn’t that. I also checked the "AC" fuse in the interior fuse box on the drivers side, all good there. I start the car, turn on the AC to check for power but not getting anything. I’m not 100% sure I’m checking it correctly with my multi-meter. I touch the meter probe to the pin on the electrical connector but it’s not showing any DC voltage, just 0.00.

A little back history, a year ago it stopped cooling, took it to the garage and they charged it up and said there is a leak. It worked fine until recently. Now the compressor doesn’t engage when you press the AC button and no air. I bought a can of refrigerant, AC Pro I think? Tried last night to recharge it. Hooked up the hose to the Low side and the gauge on the can read “Low”. Turned on the car to try and put more coolant but again the compressor never engaged and after a quick pull of the trigger on the refrigerant can, it said the system was “full”. I find that hard to believe. Guessing it just filled the line super quick but without the compressor running it’s a false reading.

So trying to figure this out. Is the compressor not running because the pressure level is too low? Or is the compressor not running because it’s shot and time to replace it? Or, am I not getting power to the compressor? Is there another fuse to check that I’m missing? I couldn’t find one other than the relays and MG Clutch fuse. Can you confirm how to test for power with my meter? Trying to fix it myself. Can’t afford the garage and it’s too hot in Florida in the summer to be without ac.

I checked for pressure last night by pressing on the Schrader valve but nothing came out. That’s when I tried to recharge as mentioned above. Can the clutch go bad but the rest of the compressor is still good? Open to all input, would really like to get the AC working again. Thanks, Chuck

 

Please do not hook up a can of R-134a to the a/c system and try to charge without reading the pressures on the high and low side of the system. You can do more damage by overcharging the system and mask the problem. Some auto parts stores have them as loaner tools, where you put down a deposit to get the tool then get your money back when you return.

Checking the pressure without the a/c clutch engaging provides little information and can mislead you. A very low charge will read about the same psi as a fully charged system without the a/c compressor clutch engaging.

For your diagnosis, how many wires are on the electrical connector to the compressor and what are the wire colors? Did you connect your black volt meter lead to a good ground like the negative battery post? Also, did you try to read the voltage between the + and - terminals of the battery to make sure your meter is working?

 

when you said you pressed on the Schroeder valve , did you do it on the low or high pressure hose???
if you did it on the low side it is not a good indicatio
First thing you have to make sure that you have enough R134a in your a/c system around 22oz full capacity i believe
start the car, turn a/c on you need to chk if you get power at compressor wire , if you get around 12 volts then compressor and or clutch are at fault
if no power, you need to chk for blown fuses if ok, chk the compressor relay.i have seen a lot of those go bad

 

Good morning, thanks for your input, appreciate it.

The battery voltage at idle reads 12.51 on my meter. With the black lead on the neg. battery terminal and the red on the connector pin I'm still getting 0.00 volts. I've double checked all fuses and I swapped out two identical relays in place of the current compressor clutch relay but the compressor won't engage. If there's an issue with the condenser fan relay or other relay could that cause this problem?

The wire color is blue with a thin red line. The wire with the connector is about 4-5" long and comes off a larger bundle of wires. I tried cleaning the connector pin but it's pretty tight and hard to get a rag or piece of emory cloth in there to clean it up. thanks for your help.

 

Here is a photo of the connector. It has one pin and some sort of plastic piece in there too.

"Male" connector to AC compressor

 

hopefully this helps

 

Thank you sir!

 

I meant to say the battery voltage with car not running is 12.51 volts.

 

All of the relays are switched on by the PCM. Most likely you have a sensor that is preventing the a/c from turning on to prevent damage.

You can try stopping by an autoparts store and see if they can scan for codes. You are looking for body codes and not the engine codes. Maybe the parts store scanners can read these for your.

I think you need to move on to testing the a/c pressure switch. The pressure switch has 4 wires and you want to unplug the pressure switch, then on the switch, measure continuity or open/closed between pins 1 and 4. These correspond to the blu/red and blu wires. Pins 1 and 4 should have continuity with proper a/c pressure. The a/c pressure switch is on the a/c line near the bottom passenger side radiator fan. You may have to access from underneath the vehicle.

 

Thanks! I'll check this out. I did check continuity between the compressor clutch relay and the male pin connector that connects to the compressor. The wire/circuit has continuity.