Joseph Jancewicz

Cadillac Sedan DeVille 1983 AC Question

13 posts in this topic

Hi,

Thanks for registering me. My AC went down on my 1983 Cadillac Sedan DeVille caused by the compressor leak. I will be replacing the compressor so need to know how many ounces of refrigerant 134a and how many ounces of refrigerant oil my ac system takes?. Also what type of oil  to go with the 134a? The ac system now is empty of refrigerant. Appreciate any help with this..

Joe J.

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Posted (edited)

The A/C charge was 3.5 lbs if I remember correctly. There should be a label on the radiator core support to verify that. It will show R-12, cuz there was no such thing as R-134 when that vehicle was made.

The oil charge depends on the amount of oil in the new compressor and the amount of oil remaining in the system. Did the freon come out all at once or was it a gradual leak? It also depends on what other components you have or intend to replace, such as receiver/drier, condenser, suction and discharge hose assembly.

Measure the amount of oil remaining in the old compressor and the new compressor. ( DON'T mix the two oils ) if the amount removed is pretty close to the same from both compressors, put the oil back in the new compressor that you took out and don't add any.

Another factor to consider is - has the A/C system already been converted to R-134? If it has NOT, then the A/C system should be flushed as the oil for the R-12 system was mineral oil. TOTAL system oil was 7-8 ounces. The recommended oil for R-134 is PAG-46. 

NOTE: There was a lot of disagreement on the mixing of PAG oil and the older systems mineral oil. There has probably been a lot of improvements in refrigerant oils and the ability of them to co-exist together. I did not keep up with that, nor have I done any research on it. SO, check it out first or wait a little while and someone will chime in. 

Do you have gauges and a vacuum pump capable of pulling 30" hg of vacuum?

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Hi,

The A/C system has been converted to 134a about two years ago. Mechanic wrote 3.37 lbs over the old label so I could not read the old label. All the refrigerant leaking out twice over the course of one year. I had it recharged last summer and this spring it was empty. Mechanic had put dye in the system in the fall and said that compressor has a slow leak. He replaced the receiver drier when he made the conversion. Should he have flushed the lines, evaporator and condenser? I probably will need to replace receiver/drier, compressor, expansion orifice (if I can locate it ) and flush the lines. I have gauges and am planning to get a Robinair Vacuum Pump 5 cfm. Thanks for the info on the oil. I was thinking of draining compressor, drier. Measuring the amount and adding the same amount plus 1 fl.oz to compressor and 2 fl.oz to drier. In addition I was going to put 3 oz in the evaporator and 1 oz to condenser. Does that sound right? First I think I will check for leaks when I get the vacuum pump. This will take some time because I don't get much time to work on it. Appreciate the quick reply.

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Posted (edited)

Sounds like you will be okay with measuring the amount of oil from the old compressor and matching that amount of oil in the new compressor before you install it.

No need to flush the system unless the orifice tube is more than 30% to 40% debris clogged. The orifice tube is located at the evaporator core inlet ( small line ). Easy way is to follow the large line from the receiver dryer to the firewall ( evap outlet ) the smaller line next to it is the line where the orifice tube is, you'll see a line connection, be sure to use two wrenches when taking any AC line connection apart. Use needle nose pliers to pull the old orifice tube out or an orifice tube removal tool. Go slow, if they break off in the line they're a real pain to remove. Be sure to replace the o-ring seal also.

The mechanic was probably okay not flushing the system. No way of knowing for sure at this point though.

Unless you find a plugged orifice tube or something is damaged, no need to replace any other components.

When installing the new compressor, BE SURE to have the suction and discharge ports covered/sealed or you will get that un-welcomed oily feeling all over...

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Posted (edited)

OoO, Almost forgot....

When you have everything back together;

Attach the vacuum pump and let it pull a vacuum for 5 - 10 mins and then close the valve to the vacuum pump and turn off the vacuum pump. DON'T disconnect the hoses.

Observe the gauges and if they move ( lose vacuum ) make sure all your connections are tight on the vehicle and the gauge set, if it continues to lose vacuum you have a leak somewhere. A SLIGHT, drop in vacuum and HOLD is normal. If everything is holding, let it sit for about 5 minutes and recheck the gauges if everything is still holding, turn the vacuum pump back on and vacuum the system for at least 1 hour to remove any moisture.  After the hour, close the valves to the pump and turn off the vacuum pump. Let it sit for at least 30 minutes and recheck the vacuum reading. If it is still holding add a small amount ( 1/2 ounce ) of dye to the charge line ( pour it directly into the line ) then connect the line to the R-134 container tap adapter, ( with the valve closed of course :) ) charge the system with 3lbs and check the gauges pressures with the AC on full cold. Low side pressure should be 28-32. Use the other 1/2 lb or less to fine tune the pressure readings.

If you have any questions, let me know

Edited by OldCadTech

THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Gm compressor change I have always drained the oil from the compressor and just added 2oz. Too much oil the system won't be very effective 

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Hi,

Is that 2 oz. plus whatever old oil came out of the compressor? I heard too much oil is not good for the system. Thanks for your comment.

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Hi All,

I purchased a new compressor (4Seasons Model 58231). It comes with a bottle of refrigerant oil PAG 150 (8fl oz). I believe my AC system has PAG 46 oil in it when it was converted from R12 to R134a. I called  4 Seasons Technical support to find out if the two oils are compatible and the answer is no. They said I need to flush out the PAG 46 from lines, evaporator and condenser. I need your opinion on this to make sure I do it right. How do I go about doing such a flush? Maybe I should return the compressor to Auto Zone and get one that takes PAG 46 oil if they have one. Confused!

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Pag-150 and Pag-46 are designators of oil viscosity. For example if I mix Mobil 1 10-30 and Mobil 1 10-40 do I need to flush the engine? Probably not.

If you are more comfortable with a match, then ask Auto Zone if they have one with Pag-46,

If it was mine. I would drain the oil from the new compressor and install the amount of Pag-46 to match what was taken out of the old compressor.


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Actually, what @barczy01 is saying is a pretty common practice.

Two ounces was pretty close because it is hard to get an accurate measurement of the amount of oil removed from the system. What he is saying is to drain the new compressor and install only 2 ounces of oil in the new compressor. That way, if the system had a little too much oil in it the oil would then be close to the correct amount. Without having the R134 evacuation and charging station, that extracts the "freon" and separates the oil into a separate measured plastic container, both methods are a a lot more guesswork than precision measurement. 

I have done it the same way barczy01 has and it works fine. I've never had it be too little OR too much oil using either method. I simply prefer to measure the oil remaining in the old compressor and add that amount to the new compressor after draining the new compressor, especially if the A/C was NICE and cold before the compressor change. If it was okay but not very cold, then it probably had too much oil in it. Either oil "method" will work.... It's only a matter of preference.


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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Did you replace the orifice tube yet? If so, was it clean, somewhat plugged with debris or totally plugged?


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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I haven't gotten that far. I'm still trying to decide what to do with the compressor and oil. Auto Zone does not have one that uses PA46. I don't want to get a rebuild. Trying to find ACDelco OEM compressor on line. Called 4Seasons again and they told me the warranty would be void if I tried using PA46. Their compressor was meant to run on PA150. They insisted I should flush out the lines and condenser to avoid future problems. So I'm looking into  the flushing procedure to see if I want to tackle it. Thanks for the comment about the orifice. I will keep you posted when I pull it.

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Pulling the orifice will determine if it needs to be flushed anyway. Check it before you get another compressor...


THERE IS ALWAYS ENOUGH TIME TO DO THE JOB RIGHT - THERE IS NEVER ENOUGH TIME TO DO THE JOB AGAIN !!!

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