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Post Radiator-swap A/C Failure

Ccwm

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#1
Soo.. just finished installing my Whoosh radiator to help combat the overheating problems I've been having when the temps outside get over 95. My '14 Fist would quickly overheat when it was that hot out and I ran the AC for more than ~15 min. Now that I've buttoned the car up and took it on a hill climb to test drive, I noticed the AC clutch will not engage to turn the pump on. I can short circuit the wire to activate the clutch by removing the relay (R6) and the car blows ice cold. I've swapped relays to test if that one is faulty as well as triggered it with the battery and checked for continuity. If I put a multimeter in the control pin slots I'm reading a steady 10.2V which should be enough to trigger the relay since I even tested that I can trigger it with a 9V battery.

The weird thing is that the relay control pin slots are reading that 10.2V even when the A/C button is turned off..

The AC blew cold last night before I did the swap. Also, using an AC gauge on the low pressure side while the AC compressor is running with the jumper wire I'm reading an acceptable 40-45ish psi.

And yes I understand the irony of doing a radiator swap so I can run my ac when it's really hot out, and busting my AC completely in the process:cry:. Any assistance or double checking that your car shows the same is much welcomed. 20220625_194746.jpg FB_IMG_1656203775856.jpg
 


D1JL

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The computer supplies a ground to turn on the AC clutch.
The weird thing is that the relay control pin slots are reading that 10.2V even when the A/C button is turned off..
This is normal, as the PCM supplies a ground (R6 pin 2) when activating this circuit.

Are you sure that you did not disconnect the (A/C) PRESSURE TRANSDUCER when you replaced the radiator?
 


D1JL

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You should also check to see if there any damage or disconnection of the high-speed cooling fan.
This too will prevent the PCM from turning the AC.

Sorry for this delayed thought,
I used to do this stuff every day but now the voids are getting larger,
 


OP
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Ccwm

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Thankyou Sir, that makes significantly more sense.

These cars only have the one high pressure transducer on the bottom of the can in the passenger side bumper correct? It seems fine as far as not being open circuit.

The high speed fan will kick on when I jumper the AC clutch so I believe that's working correctly.

Update while typing this, I put the plug back on the transducer and the AC works... Not sure how we pulled at that part of the harness during the install, and I swore I checked that the plug was tight, but I'll take the easy win!

I greatly appreciate the diagnostic assistance!
 


dhminer

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Thankyou Sir, that makes significantly more sense.

These cars only have the one high pressure transducer on the bottom of the can in the passenger side bumper correct? It seems fine as far as not being open circuit.

The high speed fan will kick on when I jumper the AC clutch so I believe that's working correctly.

Update while typing this, I put the plug back on the transducer and the AC works... Not sure how we pulled at that part of the harness during the install, and I swore I checked that the plug was tight, but I'll take the easy win!

I greatly appreciate the diagnostic assistance!
Love an easy win!
 


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