Re: [AMC-List] Still having a/c problems with 83 Spirit

[Tom Jennings <tomj@xxxxxxx>]

On Mon, 21 Aug 2006, Marty Bricker wrote:

> Still unable to determine why the compressor will not
> turn on.  I probably should've done some better t/s
> but it doesn't appear to be the low pressure switch
> that's the problem.  I replaced the switch and there
> still is no power to the compressor.  I jumpered from
> the battery to the compressor and the system is
> blowing cold air but the compressor still will not
> start on its own.  I traced the wire from the low
> pressure switch on the wire diagram and the path goes
> low press sw-thermostat-microswitch-blower switch.  
> The fuse for the compressor clutch and blower is good.
>  the switch operates the blower motor and, when
> jumpered, the system blows cold air (I assume this
> means the thermostat is working).  The write up in the
> TSM is vague so I don't know where the elusive
> microswitch is.  Should I have 12V at the connector
> that connects to the low pressure switch?  This thing
> is giving me a real beating...looking for any help. 

You just gotta get methodical. The circuit goes:

battery --> ignition switch --> fan switch* --> dash temp switch -> safety switch --> AC clutch.

*depending on model/year, the fan switch has extra contacts that the
dash temp runs through, or picks off fan voltage.

** A/C wont run if the car is off
** A/C wont run if the fan isnt running (duh)
** A/C wont run if there is no pressure in the system
** A/C wont run if it's already cold enough in the cabin


If you use a voltmeter or a lamp on a wire, one end conncted
to ground, you should see voltage on one side of the safety
switch or other iff: ignition on, fan on, temp knob cranked
to cold. Experiment turning each of those off. Voltage should
go on/off.

You can easily test the AC clutch (though  sounds like yours
is fine).  Igition off, car not running; run a wire from
battery + to the wire to the compressor clutch -- >>CLICK<<
the clutch goes on. Quite loud. Doin so with the engine idling,
you can hear the engine slow down from the load.

Even if things are not right, it'll be OK to run the compressor
for a few seconds at a time. If it's out of freon and/or oil,
running it for minutes can do harm, but it's OK to click on
to check for buildin uyp pressure -- if it is, and there;'s an
oil charge in it, it'll be fine.

If it runs and blows cold air when you jumper the safety switch,
then the safety switch is probably bad. Since you'd have to
depressurize the system to change it, you can short it and be
very careful not to run the system if doin so doesn't make cold
-- you have to be your own safety switch.

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