AC capacity and retrofit questions (Page 2/2) RWDPLZ JUN 12, 11:10 PM quote Originally posted by fierofool: You're correct. It cycles the compressor at the correct pressures for the R134a. I'm not sure how those pressures compare to the R12. 25psi for R-12, 21psi for R-134A. The original switch has an adjustment screw between the terminals, you can use a gauge set to check the pressures and adjust it, or buy a switch already preset for R-134A. Original Fiero R-12 capacity was 2.5lbs. Oil capacity is 8 oz of 525 viscosity mineral oil. gtemplet JUN 13, 10:14 AM Josef thanks for the reply, I did see those at Rockauto, I have used them for numerous parts. The Four Seasons PN #33181 ($20.79) at Rockauto, I found this one at Advanced Auto: Toughone/Factory Air PN# t33181 (19.99). Except for the 't' same part number, hmmmm. Roger thanks for the response, you are probably the only reason I'm still considering R12, I've seen your responses in other threads and respect your opinion. RWDPLZ great info, I pulled the switch off and was wondering if that was an adjustment screw. I might try to adjust it now that I got the pressure set point. Thanks for the numbers and capacity. The switch Fierofool mentioned is now $14.99 at Advanced Auto. Thank again everybody. DRMII5388 JUN 07, 06:25 PM Today I replaced compressor with HR6 with Ester oil and updated compressor switches. Then vacuumed, held at 30 then used two 6 oz Redtek cans with great result of 45 degrees, wow. 1988 Mera V6 227.000 miles with original evaporator and condenser.