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Hey guys, my Cummins conversion is hopefully in the home stretch. I’ve been driving it around town, which is an awesome feeling. One thing I’m having trouble with is the A/C system. The compressor clutch is not engaging unless I run a jumper cable directly from the compressor to the battery. For some reason my PCM is not signaling the compressor clutch to engage. I have a SwapHelper tach adapter installed, and it is reading RPM’s correctly, so I’m kinda stumped at this point.
Truck is a 2005 F-150 4.6L STX (manual AC).

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Don't think I can help with that one. Computers and I speak a different language. Might contact member A310. He just put a Detroit into his F350. Apparently your computer is looking for a signal it isn't getting. He might be of some help
 

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Don't think I can help with that one. Computers and I speak a different language. Might contact member A310. He just put a Detroit into his F350. Apparently your computer is looking for a signal it isn't getting. He might be of some help
Ok thank you. I’ll try to send him a message
 

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I just want to make sure you covered the obvious. Do you have power going through the pressure switches to the PCM and no power coming out of the PCM?

Do you have automatic or manual controls?
 

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Probably the easiest thing to do is just bypass the PCM. I haven't looked at your build but I assume you are using a mechanical cummins and are not using PCM to control idle when AC kicks on/off.
 

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Ok guys, I’m having the same problem. How do I bypass the pcm. Also mine keeps blowing the fuse for the compressor
 
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