Hey.

I'm in the middle of replacing the A/C compressor on a 93 F-250. All original, and as far as i know it has probably never been recharged, and there were no leaks anywhere. I assume it was R-12.

The Haynes manual says that you should replace the accumalator whenever the compressor is replaced. The accumlator looks fine to me. And the system cooled fine before the compressor went. Why would i need to replace the accumalator?

Also, if i am getting the system recharged, do i still need to fill the new compressor with R-134a lubricant? I would assume that the recharge would vacuum all the old stuff out, and then recharge with fresh R-134a.

 

Yes, you need to replace the accumulator. External condition tells you nothing about the desiccant bag inside. They are actually a wear item, like your oil filter, would you reuse an oil filter just because it "looks ok"? Also, at 16 years, the desiccant bag can rupture and destroy the new compressor.

Evacuating the system only removes refrigerant and/or air. It may remove a small amount of oil, but nowhere near all of it. The old oil is not compatible with R134a and needs to be removed by solvent flushing each component individually. You would then add the proper amount of BVA-100 Ester oil to the system.

If the compressor failed internally, flushing the system is even more important. Metal shavings and other debris gets blown into the system and will cause restrictions that will damage your new compressor. You must replace, at bare minimum, the orifice tube along with the accumulator.
Flushing the condenser on your 93 after a compressor failure is a real crapshoot. It is an early Parallel flow design that can't really be flushed reliably. You should consider replacing it if you had a compressor failure or at least install a filter in the liquid line.

Also consider the fact that the o-rings in all of the hose connections are 16 years old and are now on borrowed time. $6 to replace them all is cheap insurance. You need to separate all of the connections to flush anyway.

There is much more to replacing a failed compressor and converting to R134a than just bolting up a new compressor and gassing up the system. If you do it right the first time, the system will work well for years. If you cut corners, you might just be throwing money away.

 

Thanks, i'm learning on the job.

Ok, so i have the accumalator on order, picking up sat morning.

As i understand it then:

1. i need to get the systems flushed first to remove all contaminents.
2. Then, replace the accumalator, compressor, O-rings, the orifice tube, and the condensor.
3. then recharge.

Does the system recharge generally add the proper amount of BVA-100 Ester oil? Or do i need to do that prior to recharge?

Thanks for your help, appreciate it.

 

Cool! (pun intended)

You add the oil as you reassemble the system, it will take 10-11 ounces (check the underhood tag). Add 4-ounces to the compressor and spin it around a few times. Add the rest to the evaporator and accumulator.

To flush the components, get 2qts of AC flush solvent, isopropyl alcohol or lacquer thinner. Don't use isopropyl rubbing alcohol, it's 70% water. Be careful around painted surfaces.
- Pour ~10 oz in the condenser and agitate (shake it around) then blow it out in reverse direction until all solvent is expelled or evaporated. Repeat. When you think it's dry, blow it out some more.
-Do the same with the evaoprator. You can't shake it, of course. Repeat.
-Add an ounce or 3 to eack line and blow dry. Repeat.

You can get a vehicle specific oring kit at the parts store. Lube them with your refrigerant oil as you replace them. Don't forget the one on the Cycling Switch port on the new accumul;ator, that one can be a "gotcha" if you don't notice it missing.
Install the accumulator last and pull your vacuum right away. If you are having a shop evacuate and charge, have them install the accumulator. If you uncap it or install it and don't evacuate right away, the desiccant can saturate just from humidity in the air.

Good Luck