Author Topic: 1987 c10 AC stopped working after messing with vent  (Read 976 times)

Offline joshcr30

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1987 c10 AC stopped working after messing with vent
« on: October 25, 2021, 08:26:05 PM »
I have an 87 long bed with ac, and during the interior renovation process i removed the passenger kick panel where the vent is and the circular black piece has seemed to have ran off and now it won’t blow at all, but you can hear the compressor kick on but no fan. im assuming it’s because the part i removed, but i can’t figure out what it is even with the   diagram. it’s my first c10 and vehicle for that matter, any help is much appreciated

Offline frotosride

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Re: 1987 c10 AC stopped working after messing with vent
« Reply #1 on: October 27, 2021, 01:14:16 PM »
That circular kick panel with the vacuum canister is simply for fresh air versus max AC (recirculate). It is solely vacuum operated to allow outside air into the cab or stop it and should have no effect on the fans ability to come on.
If the vacuum line is off and not plugged you will have some other operability  issues and possibly engine idle issues. Simply capping the line off until you find the vent or diaphragm will help this.

Likely issues, first does this truck have Air Conditioning?
Check the fuse under the dash first...this may save you tons of time! Ask anyone here how they know this to be true..

The fans are notorious for going out due to their constant vent feature that keeps them on (when ignition is on) in a slow speed to prevent moisture from building up in the system. Verify you still have a good ground to the motor on the outside of the casing first. If it is fine you can simply unplug the power supply connector that supplies (+) power to the fan.
Using an circuit breaker or inline fuse. Connect it to the battery and verify that the fan turns on. If it fails to turn on with a good verified ground and the jumper wire (with a fuse or circuit breaker) then it is likely bad. Or if the fuse/circuit breaker pops, the fan is bad.
However, if the fan runs it should be obvious that the fan is in high speed. So move on to the next potential culprit from there.
1:  the fans speed resistors will be under the hood on the passenger side of the ac evaporator box. It is a 4pin connector in the shape of an inside down 'T'. I do not remember the resistance values of it but they should be in the wiring diagram.
2: is the relay just below this connector and behind the filter/drier/accumulator. This is the blower fan relay (if I remember correctly) this relay may be bad unplugged or bad ground)
3: is the instrument panel controller for the system. The switch itself may be bad. Doing a simple resistance check on it will give you the answer on it's condition.

Hope some of this helps. Also I hope it isn't too much info at once. I'm believe in giving all you need at once so you're not waiting around doing nothing while the current problem is driving you crazy.

With that said, be specific in your actions and go step by step.

« Last Edit: October 27, 2021, 01:24:16 PM by frotosride »
"Beat it like a red-headed ford"
1987 v10 Silverado(LQ4), 87 R10,83 K20, 83 cucv 6.2 Detroit
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2009 Jeep XK, (future LS Swap)
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