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Re: Re, Re, my first question
You should also check the evaporator temp switch, AKA thermostat switch,
which I believe is also wired in series between the control head and the
relay. It's located near the low pressure switch referred to in the reply
below, but farther to the rear and to the right, on the right rear of the
evaporator. There's even a screw for adjusting the temperature it closes
at, tweaking this might bring it back to life, at least temporarily, if
Hope this is helpful...
> From: firstname.lastname@example.org
> To: jimbo <email@example.com>; firstname.lastname@example.org
> Subject: Re: Re, Re, my first question
> Date: Tuesday, July 01, 1997 4:46 AM
> I don't know if this will help, but it sure can't hurt! First, the
> suggestion you had from Autosports in Zeeland to check the over
> pressure switch wouldn't work. That switch controls the pressure
> build-up in the system - when the pressure gets high the switch
> closes, which cycles the fan on to force air through the condensor
> thus lowering the A/C system pressure.
> There is a switch that controls (I think) the compressor clutch
> engagement. Its located underneath the black plenum covering in
> of the passenger side, below the windshield. When my friend (who
> my A/C work on both my '86 and '88 5000s) charged up my system, he
> to short the switch in order to ensure that the clutch would engage
> while charging. Apparently, he said the switch controls the clutch
> the event that the system loses freon. If there isn't and freon in
> the system, the switch will prevent the clutch from engaging,
> preventing the compressor from burning itself out. It could be that
> this switch is out. I don't remember exactly where it is, but it
> two contacts and we would pull the connector off and short the
> connector with a paper clip. If you were to do the same thing, the
> clutch should engage. Assuming your system is fully charged, then I
> would think that this switch is faulty.
> Its worth a shot.......HTH
> ______________________________ Reply Separator
> Subject: Re, Re, my first question
> Author: jimbo <email@example.com> at !INTERNET
> Date: 6/30/97 11:12 PM
> Phil and Judy Rose suggested I check the four function temperature
> switch on the underside of the radiator hose housing as a fix for my 86
> 5000 air conditioner.
> As far as the temperature gauge malfunction, Phil/Judy were 100%
> correct. When I peeled back the rubber it was a mess. Apparently
> coolant has been seeping through the switch for awhile. It wasn blue,
> green yuck inside and three of the four wires were broken, coroded off.
> Shorting two wires caused the gauge to move. Shorting any all of the
> others had no effect on my compressor though. If I want my gauge to
> start working, I'll replace it, but I probalby won't, especially at $88.
> A suggestion from Autosports in Zeeland, Michigan, was to check the
> overpressure switch located on the condensor/condenser? (the thing in
> front of the radiator by the drying thing.) (how's my terminology?)
> Disconnecting it and jumpering had no effect. I found another connector
> in the same area and disconnected it. Viola, the compressor started to
> run. Reconnecting it had no affect, so I stopped the engine and
> restarted and tried the air again. No luck, and disconnecting the same
> connector had no affect. By the way it was the connection to the
> outside temp sensor which, per the diags, reads correctly. The diags
> also tell me the control head is fine with a 00 reading.
> Autosport told me pin 8 of the control head went through the pressure
> switch to relay 11. He wasn't sure, but it might have gone through
> something else. He also mentioned a relay on the carrier under the
> dash. Haven't checked that yet. Heck of a nice guy, spent a 1/2 hour
> with me. I might even be prompted to buy something from him out of
> Now that I know several things that it isn't, what if I connected a wire
> directly from pin 8 to the control side of relay 11? Anybody with a
> good schematic confirm this for me? I didn't re post my original, but
> if this relay is manually closed (by pinky) (my test relay has no
> cover), the compressor works fine and the car gets cool.
> I was also thinking of runing wires from the relay contact inside to a
> switch and turning it on. Only problem is I don't know if the
> compressor will cycle or it is depending on this relay to do the
> cycling. I could do the cycling myself, but I am sure to get
> distracted, leave it on too long and blow up the compressor.
> Anyone with any other suggestions? I could really use the air this
> holiday weekend as I have to take a 7 hour trip.