2 Dilemmas.... A/C & Starter

[FrankieRider2]

Hope everyone here is doing fine. I haven't been posting as I've been having no problems until now... but I lurk a lot!

The current issues on my '93 K2500 are as follows:

1) The AC shuts off now regularly and will not come back on by itself. It has never done this in the 12 years I've owned the truck. This truck's AC system has always been "meat locker" worthy....

The compressor has been making both low-level noises and going through rapid engagement and disengagement during operation in both AC and Defrost modes. I took the truck to a friend's local repair shop and was told that the orifice tube filter was most likely stopped up. They pumped the system out, changed the tube filter, and replaced the R12 freon.

But the problem is still there. It is not as bad, but it still shuts off and will not come back on for several minutes regularly. I got the lecture about how the AC is supposed to cycle off and on (it does this too), but still it shuts off and the system has to be reengaged with the dash switch.

Does this sound like a compressor-related problem? I felt that it probably was with all the underhood noises and such. The shop said it sounded like a pressure-related problem to them since the system will reengage after a period of time. They think it does so when the pressure in the AC system is relieved.

They think now it is the tensioner assembly putting undue load on the belt system when the AC engages(?) since the noise is not there when the AC is not operating. Is this a possible solution or a trip up the wrong tree? There is a bit of an alignment issue with the tensioner, as the belt is really running at the back of the tensioner pulley and is not centered in the pulley. But.....?
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And.... 2) I am having trouble with my starter "clicking" when the key is turned. Is there any kind of a relay between the keyswitch and the starter itself on a '93 model truck? I've had the starter off three times and it got an extensive rebuild two weeks ago. The wiring to the starter appears to be in good shape.

The armature was burned up according to the repair shop and the rest of the starter was completely gone through. Now with everything back together, the clicking has returned. For 4 days it worked perfectly, and then the clicking started up again.

Right now I'm into these "repairs" for $400, and I'm no better off at all. I hate to think that a trip to my Chevy shop is in the works....

Any advice that anyopne might have would be greatly appreciated. Thanks so much.

[gmctd]

Both problems nay be related to the igniton switch, but -

There is a low pressure switch over by the accumulator cannister, supposed to protect the compressor in event of freon loss.

Be safer if you did this with gages, but pull the connector, put a wire jumper across the terminals in the plug.
AC should run without stopping.

If so, replace the switch

Thing of it is, there is also a couple hi-pressure cutouts, meant to protect things when pressure peaks and holds, in the hi pressure line.
Each will cause the system to cut off.

Safer to test with gages, but it's usually the low pressure switch that fails.

Check the battery terminals and cables for corrosion\oxidation, loose bolts, etc, for the starting problem.

[FrankieRider2]

jd, I replaced the low pressure switch on the evaporator, but still the AC cuts out. My dealer showed me there is also a high pressure switch on the back of the compressor at the top (and once the AC clicked back on when this switch and its associated wiring was jiggled).... but the replacement switch comes with an o-ring and a lock ring in the package, so I'm guessing I'll lose the R12 if I try to change that switch by myself?

The compressor is rattling now pretty much all the time and cycles almost continually while in the "defrost" mode but it still cools well when it runs.

The clicking ignition hasn't returned in a few days now, but I checked all the visible connections and they appear to be good. My dealer said it had to be either the solenoid or the armature bad....

I know many here don't like to use dealers for service, but in my area there is no one else that I would trust more to work on the truck. Not a lot of diesel mechanics around here....

[gmctd]

I would investigate the wiring and connectors for the ac controls, starting there at the HP switch - it is normally closed, opening at incident of high pressure.

Two-wire connector is thru-feed, jumper across the terminals.

One-wire connector is grounded thru closed switch - hook a grounded jumper to the connector.

Either case, if ac functions, switch has failed.

[whatnot]

Are you sure the noise is coming from the AC?
When the rubber broke in my crankshaft pulley, I was sure the noise was coming from the AC compressor. It would only make noise when the compressor kicked in.

[whatnot]

If the starter is ok and you only get a click, I would check the main ground cable to the starter. THe small grounds to the fenders are enough to pull the solenoid in but not enough to run the motor. It is possible for then to rot under the insulation.