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Followup To
Question -
I have a 1985 M.Benz 300SD
I have replaced the compressor, manifold hoses to the compressor, drier,expansion valve and the push button.
Low side pressure at 750 RPM is 65, at 2,000 RPM it is 35. At driving speed it will cool,but at idle it will not cool. I do see bubbles in the site glass of the drier, but am not sure if I should add 134 to the system since the low pressure is 65 at idle. Please advise
Thank you
134A ? your system should be R-12 not 134A.
Has your system been converted?
Low side pressure should be 15 - 20 psi.
Sounds like your system is overcharged.
Answer - I did change over to 134A. Why is the low side pressure at idle @ 65? and at 2000 RPM @ 35, if it is overcharged why do I see bubbles in the sight glass is this normal?
Answer#1. Did you drain the mineral oil from system?
#2. Did you replace R-12 receiver dryer with R-134A receiver dryer?
#3. Did you vacuum the system for one hour or more?
#4. Did you add the correct amount of R-134A oil?
#5. How much R-134A did you put in the system?
#6. What is your idle speed?
#7. Does your AUX cooling fan run?
Do not look at the sight glass; in your situation it is useless, it was designed for R-12 system pressure only.
Low side pressure should not exceed 30 - 40 psi; even with R-134A...
A sludge contaminated, wet system or bad receiver dryer might give you strange readings.
