1992 converted, clutch not engaging


smithae

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92 3.0 V6. I converted it to 134a back in 2015, end of last summer it started blowing hot. I ignored it because I hadn't had AC before 2015 and with work I just didn't have time. Well, it's hot as heck now and I want the AC back. The clutch doesn't engage. How do I go about jumping it started so I can check my level and possibly recharge? I can't locate the relay? Hanes manual didn't help, am I missing something?

Thanks.
 


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Bird76Mojo

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Since you said it was blowing hot air before the compressor stopped kicking on, it's probably very low on refrigerant, to the point that the cycling switch won't let the compressor kick on. You can temporarily bypass the cycling switch to make sure the compressor can kick on. The cycling switch is located on the accumulator, on the passenger side. It's easy to make a simple bypass wire with some wire terminals, or you can use a small wire with two alligator clips as long as they're protected from shorting out on one another.

But before you bypass the cycling switch, it might help to hook up a set of gauges to it first. Just to see where the system is at as far as pressures on the high and low side.

Other, more knowledgeable folks will surely chime in here soon...
 
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RonD

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In 1992 the AC switch on the dash sends 12volts thru the Pressure switch to the AC WOT relay, this relay passes that 12volt to the AC Clutch all the time, it is only used to turn off the AC when driver presses gas pedal to the floor(WOT = wide open throttle)

So in 1992 "jumping the relay" doesn't get you 12v unless the relay was bad

Yes, jump pressure switch but be careful, if "freon" is too low you can burn out the compressor, the "freon" is mixed with oil, and that oil lubes the compressor internally, the pressure switch is there to prevent compressor from "running dry" when pressure gets too low

If you add "freon" use the kind that has a dye mixed in so you can find any leaks easier
 

RangerRock

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You can check your pressures with the A/C off to get a rough idea of the current charge, should note checking static pressure is not a replacement for checking the operational pressures. With 134a your static pressures (the pressure of the Freon in the system with the A/c off) should be near the ambient outside temperature, other factors can change the static pressure like engine heat can make them higher. I believe the cut out pressure for the pressure switch would be around 20 psi if you static pressure is lower than that it will stop the compressor from engaging at all. If the pressure are above 20 but bellow a full charge that will cause short cycling (start stop repeatedly) when the compressor pulls Freon from the low side it causes the pressure to drop as the pressure builds on the high side, if the pressure on the low side drops bellow 20, it cuts the compressor to prevent damage since r134a stops carrying oil through the system bellow 10 psi.

Also if you truck still had the factory rubber a/c lines r134a does slowly seep through the lines themselves, because the R12 molecule the hose was design for is larger than a R134a molecule.
 
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