I added two cans of R134 (24 oz) clutch kicks on but only warm air out. High pressure sticks on 120 psi but low side drops off to negative 5, and the compressor is noisy. What could it be? Do I need to add more Freon? Thanks much, Ray.

I vacuumed the system and R134a in 23 oz is required. One of two cans-12 oz each, is with UV leak detector. I don’t find any leak externally but am not sure about the expansion valve and the condenser, because it is hard to see. Anyway, the compressor, dryer, and expansion valve were replaced recently. There are two things I doubt about:

More PGA oil might be needed for the compressor, and

There could be a leak between the condenser and expansion valve.

Does this make sense?

  • Welcome to Motor Vehicle Maintenance & Repair! I don't think you're reading the low side at the correct time. I believe when the compressor is kicked on, it will drop the pressure on the low side, then the pressure will kick back up as it kicks off. Also, what was the reason for adding R134a (which actually isn't Freon) in the first place? If you lost the charge, did you properly vacuum the system prior to adding more R134a? Was the system completely depleted? – Pᴀᴜʟsᴛᴇʀ2 Nov 11 '17 at 4:03

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