AC System Oil?

[koonpup]

Hello everyone, I have a 1974 Roadrunner that was completely stripped. I have restored everything and the last thing on the list is the AC. I gathered all of the parts I needed and installed them. I put all new o-rings in and a new condensor as it was damaged. The compressor clutch will kick in so I think it is fine. I put a vacuum pump on it for an hour and it pulled 28 and held it. Now before I charge it, do I need to put some oil in it? I would imagine so since it has been apart and hasn't been ran for 20 years. If so, how much do I put in and where? Thanks in advance!

 

[Meep-Meep]

Yes, you will need oil before you charge it but first make sure you have no oil to begin with. Drain the compressor and anywhere else it likes to hide. Then pump on it to get the moisture out.

 

[AMX364]

The bigger question is what oil to put back in? If R12 then one type, if R134 then a different type. AND they do not play together at all! As said must drain compressor and measure what you have and how much.

 

[koonpup]

Thank you for the replies! Yes I will need to know what kind of oil since I'm converting. So the only thing I need to drain is the compressor and replace with the exact amount I take out? No extra for anything else like the new condensor I put in?

 

[idrivemopar]

If you are running the original RV-2 compressor, you will use Ester 100 oil. I believe it takes somewhere between 9 and 11 ounces. The service manual has a procedure to measure how much is in the compressor, I have never seen any stated amount in my service manual. Also, if this is a 134a conversion, you should have your hoses updated for 134a, because of the molecule size, the R-12 hoses can allow 134 to bleed out. Also, the epr valve in the compressor should be removed and you should use a external thermal cut off switch. Also, O-rings should be the green ones, not black. Also, did you do a new receiver/drier?

I just went through all this with my 73 Roadrunner. Also, if the system has been open to the atmosphere, make sure your evaporator has been thoroughly flushed, other wise you will get contamination and clog the filter on the low pressure side, as I found out the hard way!!!

 

[uwss]

As an a/c tech; you need to purge it with nitrogen to get all the old oil out. Next you can buy synthetic R12 which will have the similar properties as the original. Pull a good vacuum. The refrigerant has oil in it. Charge by weight, If you want superior coolant add a relay to block the coolant going to the heater. The heater puts an additional load on your a/c. Your car will get about 20 degrees cooler using that method. You want the relay to energize when you select cool.

 

[koonpup]

I did like you guys said. I put green o-rings in, put a new drier, new condensor, put new oil in the compressor, and flushed the evaporator. It holds a vacuum and the compressor clutch kicks in (when you bypass the switch of course.) Now I tried putting refrigerant in it, 134a and it will not take it for some reason. I start the car, put the ac and fan on max, and get the compressor going. The can doesn't get cold at all and the pressures hardly raise. Any ideas? Thanks for all of the help.

 

[5.7 hemi]

Put the can in hot water.

 

[koonpup]

I will try that right now, thank you! It is 95 outside right now

 

[HawkRod]

Are you sure you are putting it in the suction side?

 

[koonpup]

Yes I put it in the low pressure side(blue). I put the can in hot water and it accepted it. Now my problem is, after the first can, the low pressure side is reading 108 and the high pressure side is reading 99. What is going on?