QuestionCan too much oil in the compressor stop it from engaging with the system charged? I made sure the orfiace tube and accumulater are not blocked. I jumped the connector on the plug on back of the compressor and it engages but no presure builds to trip the high presure fan switch, also the lines do not change temperature ...as if the compressor isn't letting in anything, could this be a bad control valve in the compressor? when the compressor plug is jumped and the compressor is turning, there are no unusual sounds or anything....meaning it spinning freely. what do u suggest I do from here?
AnswerJohn,
Well, you seem to be on the right track. If the orifice is properly installed, and the system is properly charged, then the system should function normally. The orifice separates the high side and the low side, but the location of the high side port is important. If it's after the condenser, then the reading on the gauge can be lower than normal. The condenser can be clogged (even partially), and show a low, or even non-existent high side pressure. The biggest problem you have, right now, is the fact that the high side outlet from the compressor, in a properly charged system, should be HOT -- indicating the compressor is actually compressing.
As for too much oil -- that's only a bit less dangerous to the system than too little oil, although most people don't buy into that. Fact is, particularly in R-12 systems, it was common practice to shoot a can of oil charge in during service. Over the years, the oil can build up, and refrigerant performance goes way down. Still, I don't think this is your main problem here. Provided you have no restrictions, you seem to have a blown compressor.
The control valve in a variable displacement compressor (wobble plate) definitely controls compressor output, based on the suction (evaporator) pressure. In the event of a low-stroke condition, it *does* vent excess pressure to the crankcase. Could it be the culprit here? Possibly, but I've rarely seen it, if ever. Now, I haven't touched one of these in over 10 years (GM is my old days!), and even then, we didn't overhaul them at the dealer. Following this route, you'd need to consult someone that overhauls these things for a living. I know it's much less than a new (or even rebuilt) compressor, but the cost is always in a factor with a car that's closing on 20 years. Plus, given the cost of R-12 (unless you've converted), repairs on this system might take you over what the car's worth.
If it were me, I'd evacuate the system properly, using an approved station, and vacuum the system for a *long* time. Then, recharge with the proper amount, to get a good idea where you stand. I know it seems like square 1, but better to be safe, with a clean slate, then be sorry, with an inaccurate and costly mis-diagnosis. Good luck!
