Charging A/C

[olds1995]

1995 Olds Cutlass Supreme FWD.
I evacuated the system and it held vacumn for over an hour. I started adding freon, 134A, with a relatively new set of gauges.
Problem is the compressor clutch won't engage (I guess no pressure safety???). I recall back in the 60's-70's using a paperclip/jumper wire inserted someplace to get the old ones kick-started.
How do I get the '95 compressor clutch to engage?
Thanks, Marvin

[brcidd]

Your variable compressor system does not have a cycling switch- because it does not cycle-- it destrokes inside the compressor to avert freeze-up. Compressor will come on by itself (when system pressure exceeds 47 psi) if all conditions are correct- the pressure is monitored by a pressure transducer (3- wire) on the high side liquid line- do not try to jumper this- will cause undue harm to your electronics..

One thing your car a/c system is known for- is the power steering pressure switch failure- due to corrosion, the switch may be broken off entirely-- it is normally open- so unplugging it may help-- look for it under driver's side on power steering high pressure hose behind front left wheel, under car..this switch is there in only a few years and only on W-cars - intent is to turn off a/c compressor when in tight parking maneuvers so as not to stall the engine...it was replaced in later years by the stall saver routine- that meerly shuts off a/c when engine rpms drop below 500...

I have unplugged about a dozen of those switches- be sure to tape it off- otherwise oil change machanics will plug them back in- and you won't have a/c again-- if this is what the original problem is..

[olds1995]

Originally Posted by brcidd

Your variable compressor system does not have a cycling switch- because it does not cycle-- it destrokes inside the compressor to avert freeze-up. Compressor will come on by itself (when system pressure exceeds 47 psi) if all conditions are correct- the pressure is monitored by a pressure transducer (3- wire) on the high side liquid line- do not try to jumper this- will cause undue harm to your electronics..

One thing your car a/c system is known for- is the power steering pressure switch failure- due to corrosion, the switch may be broken off entirely-- it is normally open- so unplugging it may help-- look for it under driver's side on power steering high pressure hose behind front left wheel, under car..this switch is there in only a few years and only on W-cars - intent is to turn off a/c compressor when in tight parking maneuvers so as not to stall the engine...it was replaced in later years by the stall saver routine- that meerly shuts off a/c when engine rpms drop below 500...

I have unplugged about a dozen of those switches- be sure to tape it off- otherwise oil change machanics will plug them back in- and you won't have a/c again-- if this is what the original problem is..

brcidd, Thanks, your A/C brilliance is only exceeded by your willingness to share. I didn't know about the 47# so I hooked up a new can and opend the valve and waited. When the low side reached 47# the compressor kicked on and I completed the charge. Thanks again.
Marvin