i have a 1989 gmc r3500 with a 454.my ac line started to leaked and it leaked out all the r12.i was wanting to know whats the proper way to change it to r134a?do i just need to get the port adapters and fill it with 80 perfect r134a and add the new pag oil or will the old r12 oil need to be drained?
help with refilling ac system.
- Thread starter wes104
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Trying to remember, I haven't dealt with a conversion in a while. As I recall you need to dump out the old mineral oil from the compressor, and flush it out of the rest of the system as it's not compatible with R134a. You'll also need a new receiver-drier that's compatible (all the new ones are) as well as new, compatible O-rings. Ester oil is used in R12->r134 conversions since there's always going to be residue from the old oil present, and pag oil is not suitable for that.
Usually on a car that old the amount of mineral oil left in the system is very little. I would not worry about that. Replace the accumulator with one compatable with r134a. Any new one will be.
Replace the orifice tube with an orange one. Add 3.5oz of oil per pound of refrigerant. I would put a little extra. An 8oz bottle of ester. Add r134a fittings. Vacuum and fill to 85% of the r12 charge.
Replace the orifice tube with an orange one. Add 3.5oz of oil per pound of refrigerant. I would put a little extra. An 8oz bottle of ester. Add r134a fittings. Vacuum and fill to 85% of the r12 charge.
Would you try to drain the compressor?
Repair the leak. Then replace the accumulator since it's also the drier and the orifice tube with the one Chris142 recommends. Use ester oil, and the entire 8oz bottle of it. ACKits.com used to carry BVA Auto 100, GM used to recommend the blue PAG oil they had. Evacuate and recharge only with pure R-134a, don't use AC Pro or anything similar!
The leak needs to be repaired. And replace all o-rings on a vehicle that old.
Do you have the equipment to fill by weight?
Do you have the equipment to fill by weight?
Originally Posted by meadows
Would you try to drain the compressor?
No. I have been told that any leftover mineral oil will help the non barrier hoses seal.
Would you try to drain the compressor?
No. I have been told that any leftover mineral oil will help the non barrier hoses seal.
Originally Posted by joegreen
You could fix the leak and get a shop to put r12 back in. Might be the easiest thing to do.
Good luck finding a shop that still deals with R12.
You could fix the leak and get a shop to put r12 back in. Might be the easiest thing to do.
Good luck finding a shop that still deals with R12.
Originally Posted by Chris142
No. I have been told that any leftover mineral oil will help the non barrier hoses seal.
The way I learned it is the mineral oil is not soluble in R134a so it just kind of sits there reducing cooling system capacity. In an old system there will be residue embedded in the hose material even if you get out as much mineral oil as possible.
There's a lot of good AC information in the aircondition.com forums:
https://forum.aircondition.com/
No. I have been told that any leftover mineral oil will help the non barrier hoses seal.
The way I learned it is the mineral oil is not soluble in R134a so it just kind of sits there reducing cooling system capacity. In an old system there will be residue embedded in the hose material even if you get out as much mineral oil as possible.
There's a lot of good AC information in the aircondition.com forums:
https://forum.aircondition.com/
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