A/C stopped working after engine swap
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Joined: May 2001
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From: Baltimore USA
A/C stopped working after engine swap
I swapped 351Ws in my 1986 Bronco and the A/C has stopped working. When I did the swap I only removed the brackets and set the A/C Compressor aside. I have checked the caps and there is pressure in the system (don't know how much psi). The clutch no longer cycles on and off like it used to. I checked the connectors with an volt meter and the signal goes all the way through the compressor. I also tested the wires to it and there is power when the A/C is turned on. Is there a way to tell if it is the clutch or compressor that is having a problem without discharging the system?
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Joined: Nov 2002
Posts: 9,987
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From: Memphis, TN
A/C stopped working after engine swap
The problem is electrical, if the clutch never engages but there's over 25psi in the system. Turn it to MAX A/C with the key in RUN and check for 12V to ground on each wire of the low-pressure switch screwed onto the side of the accumulator. Then do the same at the clutch connector just behind the pulley on the compressor. If you have 12 everywhere, you have a bad ground from the clutch connector's second wire. If you have 12V on one of the clutch wires and ground on the other, the clutch magnetic coil is bad. If only one side of the pressure switch has 12V, the pressure is below 22psi, or the switch is bad.
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Senior User
Joined: May 2001
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From: Baltimore USA
A/C stopped working after engine swap
Ok, I did some of that checking. The low pressure switch gets 12V, but it doesn't send any signal to the compressor. The other day I checked the wire at the compressor and it was sending it then. Wouldn't the low pressure switch not send the signal if the pressure is fine? Isn't is supposed to turn the compressor on when the pressure is too low, not when it is fine? I also grounded the compressor and jumped it straight to the battery. with the truck off I can hear the compressor click. With it on it still does not kick in. I tried to use a tire gauge to check the pressure at the accumulator, but it would not seal all the way. However even without sealing all the way it was showing 21 psi.
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SleeprLegend
1987 - 1996 F150 & Larger F-Series Trucks
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Apr 22, 2011 08:43 PM
