Thread: Any A/C experts out there?

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Denny's right on the money, I would suspect it's a stuck expansion valve, It does concern me that you said you did not add oil as most compressors are shipped with out oil in them. Your low side is positiveley too low, but the high side doesn't seem outa reason as with R134a with temps in the 90's I usually see about 40 on the low side and around 250 on the high side as an average at idle speed. rule of thumb on the oil is 2oz for evap. 2 oz for condensor,1 oz for hoses, and then the compressor will need whatever the compressor manufaturer calls for. Either way I would first put a new expansion valve on it, I say expansion valve instead of orfice tube because all of those units I've seen use an xvalve....

troy-cryer makes a lot of sense also,maybe try letting some gas out of it and see what happens,because if it's putting out 38 degrees at the vents there can't be a hole lot wrong as most oem stuff I work on will only put out about 45-55 degrees at the vents.....

Not a auto ac tech, but the metering device sounds like the problem. High head usually gives you high back pressure. A restriction will drop your low side pressure and the more refrigerant you add the lower it will go, hence slugging the compressor with liquid, not good. Is the suctions line sweating?
Is the metering device rated for 134A? 36 to 38 degrees to cold, kinda also sounds like improper size condensor. Wish I could help more, just thought I add my 2 cents. Stu Cool.