89 740 GL A/C recharge problems

The A/C started blowing ambient air, no cooling, and the A/C clutch was cycling. The car has been converted to R134A. I got three cans of 11oz refrigerant, plus stop leak and detector, and attempted to get it cooling again. Got all three cans in after a long while, for a total of 33 oz. /2 lbs. However, the clutch is *still* cycling, but a little faster it seems. No cooling. Don't have any specs on what the charge is supposed to be...but I guess it wouldn't do any good to know that as I don't know how many ounces were left in the system. There must have been quite a bit of refrigerant left in the system, as it was showing about 85 on low side and 145 on the high side before adding any. It is about 100/150 lbs (A/C set on max cooling) after adding more. After I shut it down and the pressure equalized, the static pressure was 128 lbs. At what pressure is the low press. cutoff switch supposed to activate? BTW, this is what was causing all of the dash warning lights to flash on every 2 sec or so. You turn the A/C off, and the flashing dash light problem goes away! Weird!

Yea I know you should change the receiver/dryer, evacuate the system and put recommended factory charge in , etc. etc. Is my cutting corners causing a problem?

Reply to
Jim Caldwell
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Should run 28 to 34 pounds on the low side.It is GM system.Pull the hose on the dryer that goes to the front of the car and clean the plastic tube.

Reply to
Rod Gray

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