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Old 05-01-2021, 09:18 PM   #8
fdryer
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Join Date: Jan 2006
Location: NYC
Posts: 45,036
 

2003 L-Series 3.0L Sedan
Default Re: A/C Clutch Wiring Connector

With so much info given, I neglected to include some more. Approximately 40 psi is the target pressure when the pressure sensor determines too little refrigerant left (very little lubrication) in the system to trigger the disable signal sent to the pcm. Pressure sensors are mechanical and not precise (+ or minus a few psi). With more info, you described a typical leak since you refilled the system that already leaked, enough to provide cooling for a season, last year. A leak continues whether the system is running or not. Buy and use an inexpensive uv blacklight to find the source of the leak. Examples of dye are in both service valves. When you topped off/refilled the system and disconnected the refill can, did you see dye? Leaks can be worn service valves with loose caps, compressor front shaft seal, fittings, crimped fittings, break in hose, condenser coil damage, etc. A uv light shined over the entire system will show where the leak(s) are. Normal wear and tear from driving rattles ac plumbing made of soft aluminum trying to restrain up to 450 psi, the safety blow off pressure at the compressor to prevent hoses from exploding if incorrect servicing is performed like overcharging or using other refrigerant as a substitute. Every refrigerant used in home, portable, central, business systems are formulated for best performance. This also means different operating pressures and volume.

At this point, you're refilling a leaking system so its your choice to continue refilling or attempt to find the source of the leak then decide if you can make repairs and complete it by using a vacuum pump, check for any more vacuum leaks before refilling with 1.5lbs of r134a. If you decide to attempt repairs, you become the ac specialist. The alternative would be saving money by repairing the system then having a shop perform the evacuation and refill. Whether a shop will test for any leaks is up to them to inform you as they prefer to do all the repairs to reap the most profit. The most money spent would be a repair shop performing what I described, marking up any parts needed, hourly labor rates plus a percentage for overhead costs and profit - several hundred dollars.

When you raise rpm above 1200 and don't see the high side pressures increase above 125 psi, your system leaked out most of the 1/5 lbs of refrigerant. A guess is less than 8 ounces remains in the system, far below the 1.5 lbs needed.
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