I have a 1994 gmc sierra. i put a new ac system in for the second time. after vacuuming down the system and determing all is well, we begin to add refrigerant. the clutch then begins to engage and disingage rapidly, even as we add additional refrigerant. we have installed new low pressure and high pressure switches.. any suggestions?
It will short cycle while refrigerant is being added slows down when level starts to reach normal
SOURCE: ac clutch will not engage 1998 gmc sierra
sounds like low or no refridgerent in the system. start there. You can the cycle switch (low pressure switch on the side of the reciever dryer. the alumunium can on the left side of the engine in the back. You can also jump the two pins with a jumper wire and see if the compressure turns on then. Do not let it run for more than a min. you could burn up your compressor.
Good luck
SOURCE: Fuse is OK but air conditioner doesn't work '94 GMC Yukon.
yes alow presure switch is likely on GM and it could be out of freon ,safe way to tell is to put a set of gauges on it and it will tell by passing the low side switch will just destroy the compressor if it is out of freon
SOURCE: 1991 Sierra GMC AC control problem
The follwing is a cut and paste from a service bulletin:
Bulletin No.: 461202
Date: May, 1994
SUBJECT:
A/C CONTROL HEAD FLASHES OR ERRATIC OPERATION OF A/C CONTROLS (POLISH
TERMINALS)
MODELS:
1988-94 CHEVROLET AND GMC TRUCK C/K MODELS
1990-94 CHEVROLET AND GMC TRUCK TOPKICK/KODIAK MODELS WITH C60 OR C69 AIR
CONDITIONING
CONDITION:
A/C Control Head flashes, performs erratically or malfunctions.
CAUSE:
Light surface corrosion on the Control Head terminals.
CORRECTION:
Remove the A/C Control Head and while holding the unit with the terminal
cavity down (toward the floor) so no particles will fall inside on the
circuit boards, polish the terminals on both sides of the cavity with a lead
pencil pink eraser. Do not use an ink eraser or other abrasive such as a
small wire brush or sandpaper, etc. Doing so will remove the terminal
coating and degrade the contact surface.
Performing this procedure, in many cases, will make replacing the Control
Head unnecessary. Using this procedure in conjunction with the A/C circuit
diagnosis found in the Electrical Diagnosis Manual and especially before
replacing a Control Head for any reason is recommended.
After polishing the Control Head terminals, but before reconnecting, check
for proper terminal contact as described in the applicable electrical
diagnosis manual. If contact is good, apply dielectric grease (P/N 12345579)
to the harness connector terminals. Please do not apply grease to the
Control Head.
SOURCE: 1992 gmc c1500 ac compressor relay location
I pulled this from another web site
"The AC clutch relay is located inside the cab on a metal bracket that is easiest to see when you remove the glove box compartment.
The relay is on a metal bracket bolted to the top of the plastic air box, forward and to the center of the dash from glove box.
There are three relays in a row on that bracket. The AC clutch relay is the end one closest to the driver’s side."
Testimonial: "Right on target... THANKS"
SOURCE: LOW OIL PRESSURE ON 2007 GMC SIERRA 1500. CHANGED
have it tested using a manual gage if still low then main baring ore most likely bad that would mean a over hall if is really low and bearings bad should be making rattle noise when started up first few seconds
Testimonial: "thanks alot.truck is not making a rattling noise.we did check it with a manual gauge.it read about 10 at idol. press. gets better as you incr speed"
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