custom swap, trying to figure out the AC. I both plugs going to the compressor have 12v

[nicklatech]

I did a custom swap and removed the chevy 5.7 and dropped in a cummins. I had to rerun many wires so its very possible that I screwed up the wiring.

I took my multimeter and started testing the plugs. At the compressor I have 12v from the plug by the pulley. This 12v seems like its always on as long as the truck is started. The plug in the back side of the compressor also has 12 volts, but only if AC is turned on. Does this sound correct? If this is correct this its possible that I might have the wires backwards on the plugs if that matters.

Thanks
Nick

 

[nicklatech]

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I have 12v on the green and the black wire is grounded. The clutch doesnt engage, is there something else I need to connect to test the clutch? Do I have to connect the pressure sensor in the back?

 

[Black_cirrus]

Try an old school test light with an incandescent bulb make sure it lights up that's a real load unlike a multimeter. The pressure switch I would think needs hooked up to get the 12v to the clutch (triggers the relay).

 

[MSCustoms]

I dont know what ac compressor you have but typically the clutch will not engage if there is no pressure from the refridgerant. Aka low refridgerant

 

[grampadirt]

Also,the low pressure switch on the accumulator needs to see at least 20 psi(or so) to allow the clutch to engage.Is it plugged in?

 

[nicklatech]

I just purchased a new compressor, but I cant lock it up either.

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How can I do a test clutch lockup on the new compressor and my old one? I want to make sure that electromagnetic clutch is good. I though it was bad which is why I purchased a new compressor.

 

[nicklatech]

Try an old school test light with an incandescent bulb make sure it lights up that's a real load unlike a multimeter. The pressure switch I would think needs hooked up to get the 12v to the clutch (triggers the relay).

i tested the bulb with the battery first. next wired it up to the switch and the bulb didnt light up. Then I double check the wires with the multimeter and it showed voltage. So you are correct. So does that mean my AC relay isnt getting triggered?

 

[Black_cirrus]

Probably, low pressure switch like already said, You can hear the clutch engage when you apply power when its working right. I've used a paper clip to bypass the relay to test various things. And I'm cringing at your unsealed butt connectors, I spent my morning fixing someone elses poor wire testing and hacking that left corrosion in the abs wiring on a 2008.

 

[nicklatech]

Probably, low pressure switch like already said, You can hear the clutch engage when you apply power when its working right. I've used a paper clip to bypass the relay to test various things. And I'm cringing at your unsealed butt connectors, I spent my morning fixing someone elses poor wire testing and hacking that left corrosion in the abs wiring on a 2008.

so if i jump the AC relay then I should be able to hear my compressor clutch click? Can I paper clip test the low pressure sensor also? The ac worked before the diesel engine swap and I had to extend all the AC wires so its possible there is a bad wire somewhere.

 

[nicklatech]

ok, I jumped the AC relay and the compressor kicked on,YEA its some cold air thats blow. when I put the relay back nothing.. I tried jumping the sensor on the accumulator, and jumping the sensor on the back side of the compressor and jumping the sensor on the hi/low ports. Still nothing.


Any ideas to debug? I guess I should start tracing the AC relay input backwards to see why its not tripping. Anyone have a diagram? Does the AC relay need anything else beside those sensors I talked about above and the AC button? Is there other ECU input that is needed? (i dont have an ECU anymore)