Air Conditioning help

T

texastruck

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My Cummins swap is in the home stretch now. I’ve been driving it around town searching for any issues that pop up. One thing I can’t seem to figure out is the A/C system. I can’t get the PCM to signal to the A/C compressor clutch to engage. It will only engage if I run a jumper wire directly from the compressor clutch to the battery. I have a SwapHelper tach adapter installed, and I verified that it is indeed working. I’m kinda stumped at this point.

Truck is a 2005 F-150 with a 12v Cummins.
 
What PCM are you running? If your running the Dodge PCM it’s going to have to see the ESS signal to run the A/C and the alternator. Is the alternator working?

Why not just put it on a switch? That’s the way I have mine. Flip it on anytime in any vent position.
 
BigPapa said:
What PCM are you running? If your running the Dodge PCM it’s going to have to see the ESS signal to run the A/C and the alternator. Is the alternator working?

Why not just put it on a switch? That’s the way I have mine. Flip it on anytime in any vent position.
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I’m using the stock Ford PCM. The whole A/C system is the stock ford. Was working perfectly before the swap. If I put it on a toggle switch, wouldn’t I have to remember to cycle it manually? Isn’t the compressor not supposed to run continuously? Either way, adding another switch in my cab is my last resort, but thank you for the option.
 
Are you using both the crank and cam inputs to the Ford PCM?

Sent from my motorola one vision using Tapatalk
 
From ALLDATA. This should help you know what to check.

AIR CONDITIONING CLUTCH RELAY (A/CCR)

NOTE: The PCM PIDs Wide Open Throttle A/C Cut-off and WACF are used to monitor the Air Conditioning Clutch Relay output.

The Air Conditioning Clutch Relay (may be referred to as the wide open throttle A/C cutoff [WAC] relay) is wired normally open. There is no direct electrical connection between the A/C switch or Electronic Automatic Temp Control module and the A/C clutch. The PCM will receive a signal indicating that A/C is requested (for some applications, this message is sent through the communications network). When A/C is requested, the PCM will check other A/C related inputs that are available (such as Air Conditioner Pressure Switch, Air Conditioning Clutch Cycling Switch). If these inputs indicate A/C operation is OK, and the engine conditions are OK (such as coolant temperature, engine RPM, throttle position), the PCM will ground the Air Conditioning Clutch Relay output, closing the relay contacts and sending voltage to the A/C clutch.
Click to expand...

Sorry, I confused myself with what you were saying. All you're saying is that the A/C CLUTCHwon't engage, correct? I had in my head you were saying the A/C SYSTEM wasn't working.

You are correct about putting the A/C Clutch on a switch, wouldn't want to do that. What I was referring to is on my Dodge. The "A/C Switch" is integrated into the mode knob on the HVAC panel. The A/C SYSTEM will only come on when it is in the normal A/C position, the Max A/C position, or the defrost position. I basically took that "switch" out of the panel so now I can turn my A/C SYSTEM on in any vent position.
 
You COULD do a toggle switch, just put a thermostatic and probably switch in line with it.

I’d prefer to get it working without it, but if you NEED IT, it would work temporarily.
 
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When I 12v swapped an 03 ram 1500 I did away with all the electronics and just wired the AC like an old school system with a pressure switch/cycling switch on the low side. Had it powered through a relay/toggle. So all you did was flip the switch to turn it on and the cycling switch handled the rest. Drove it this way for 2+ years in southern heat
 
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