Filled AC with freon but no compressor oil

[jcm]

After installing a new compressor, took the car to a mechanic with proper tools to energize AC system.

Mechanic did not install oil. Compressor clutch did not engage without oil. Mechanic instructed me to fill the low side with oil rather than bring it back to him. I picked up the 3 3oz cans with connection hose. Mechanic said he filled 32 lbs of freon and stated there was "room" for the oil fill.

Q's:

1. Is this a correct procedure?
2. How do I know how much of the can installed by just using a hose without gage?

[jakejm79]

Did the compressor contain any oil when it was installed, most new ones come filled, it is then advised to drain it and add the required amount depending on what you replaced (see below).

Draining of R134a = 20ml
Burst AC Hose = 40ml
Replacement of Hose = 20ml
Replacement of Condenser = 40ml
Replacement of Evaporator = 40ml
Replacement of Expansion Valve = 20ml
Replacement of Compressor = 70ml

I assume if the compressor was the only thing you replaced then you would have to add 90ml (70ml for the compressor and 20ml for the R134a recharge) of oil (~3ozs).
The mechanic added 32Lbs of freon, 1st off 32Lbs wouldn't fit in the system and 2ndly he shouldn't be adding freon at all ng900's and og9-3's took R134a. Do you mean he added refrigerant until the reading was 32PSI???

Anyway to answer your questions:
1. Most definitely not, I suggest taking the vehicle to a trained AC specialist or at least someone that can communicate correctly.
2. By weighing it before and after.
A completely empty system will need 725gs of R134a (~26ozs) and you use the information above to calculate the correct amount of oil.

Also I don't believe that the reason for the clutch not engaging is the lack of oil, while low (if the compressor was drained prior to install) the system should not be completely empty of oil, I suspect that the pressure is not correct and the pressure switches are disabling the compressor from running to prevent damage.

[jcm]

Thanks for the reply Jake. He added 134a, ignor my generic freon call-out, until the guage read 32 lbs. I did not install any oil in the empty 40K mile donated compressor, left this to the pro. So there was only oil in the lines.

Shall I install a can of oil and see if the compressor kicks on? This at least will give the answer that I have a functioning unit. If I understand you right, there will be no way to know how much oil is truely in the system without weight. I thought the weight related to 134a not oil.

Perhaps you'll give another shot at guidance.

[jakejm79]

Ok no problem on the freon thing, I assumed that was what it was, just wanted to double check, heard many a shop do a funny thing.
You should be good with just one can (3ozs) of the oil based on what was replaced and the compressor being empty that should be enough. If that doesn't solve the clutch not kicking in then I would look at the high and low side pressure readings. While the pressure reading on the low side is used has an estimate for measuring the level of R134a the 'correct' pressure reading can vary depending on outside temp and engine RPM. So it is normally advised to completely empty the system of R134a and then add the correct amount by weight.