QuestionSymptom: after pulling 28lbs of vacuum, then let it rest for about 1/2 hour to make sure the vacuum stayed.. Connected the freon can, with the engine running, open the valves. About 6oz of freon were pulled into the system, then no more. The compressor would cycle in the right back out. During this cycle the low pressure wwould go to about 65, then the compressor cycles in, the pressure drops to about 45, then the compressor cycles back out... The high side seems to stay pretty much at around 65~70.. Got any ideas?
AnswerMike,
I don't know your knowledge or experience level, so forgive me if I sound patronizing. I need to cover a few things first...
-Are you charging on the low side or the high side (blue or red lines)? For a can tap, the usual method is to charge on the low side, for the danger of the can blowing up from the pressure on the high side. On RRR stations, you normally charge on the high side, since the refrigerant is propelled fully into the system. Myself, I like the high side, for fear of installing liquid into the compressor (not too bad when the fitting is before the evaporator) -- remember, you can't compress a liquid. Regardless, conventional wisdom says charge through the low with cans.
2. After you punch the can in the tap, are you setting it down or just holding it? Most cans need help, in the form of a shake or wrapping both hands around the can and letting the warmth help the refrigerant transfer. If left to it's own devices, it'll take a while to clear a can by itself. I'm assuming this is either R-12 or R-134a, and not one of the alternative refrigerants!
3. Are you closing the service valves after you install the refrigerant? The readings will not be accurate unless you do so -- I only open the service valve I'm charging through, as well. You create a kind of pressure loop if both are open -- the readings won't even be close to accurate.
That said, what was replaced? That could tie in directly with the problem, so keep that in mind as I type in more. Did you remember the Orifice tube? When the compressor engages, the high side should rise, while the low side should drop -- to an extent. You seem to be getting no increase on the high side, which leaves me to believe an O-tube (missing) or Expansion Valve (open) problem, or a compressor problem. 45psi is somewhat high for the low side (28-38 unless ambient temp is way high or way low), and 65-70 is nowhere near normal (at least 150). Confirm the Orifice is there, or the Expansion Valve is working (sometimes a light tap with a rubber mallet gets 'em going), and then look at a possible compressor problem.
Good luck!
