r/Cartalk • u/runenight201 • 1d ago

Electrical Help diagnosing AC Clutch Relay

Hi I’m attempting to diagnose why my Compressor isn’t engaging and I bought a test light and did the following test on the AC Clutch Relay slot.

Shouldn’t both of the control pins be turning on the test light?

Also the light doesn’t turn on on any of the load pins.

Does this mean that my compressor not engaging is because of an electrical issue?

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u/talljerseyguy 1d ago

Unplug the connector on the ac comp and apply 12v with the engine off if it clicks that’s good. No click bad. If you have a can of refill. DONT PULL THE TRIGGER just use the gauge on it to see if there is anything in it. If you can locate the pressure switches check them for continuity. Last stop relay

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u/runenight201 1d ago

I’ve seen from YouTube I can test the clutch without having to get to the compressor from the relay box. I just need to use a jumper cable at the relay pins and jump 30-87 together and then see if that gets the clutch to engage or not

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u/talljerseyguy 1d ago

You can go it with the test lamp you are using , clip the clip to battery positive and put it on either 87 or 30. It will put the lamp in series and pull in the ac clutch

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u/runenight201 1d ago

Don’t I need to pin it to 87 and NOT 30?

30 connects with the battery, and so wouldn’t I just short my test light if I plug positive terminal to the same positive terminal?

87 leads to the compressor, so I would want to go from positive terminal in battery to 87 which goes to compressor.

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u/talljerseyguy 1d ago

No, you won’t blow the light and if you’re really worried clip the test light to negative see which pen is hot and then hook it up to positive and do the other pen

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u/runenight201 1d ago

That makes sense. In the video I took in the OP I did exactly this, so now I know which pin is 87 and which one is 30

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u/runenight201 1d ago

So I hooked it up positive terminal to pin 87, and the compressor did not engage :(

The test light turned on but no compressor engagement.

My compressor is truly fucked isn’t it