Pag vs Ester on 134a retrofit (1 Viewer)

[John Smith]

I am retrofitting my 84 Suburban's AC system from R12 to 134a. My question is should I use PAG or Ester oil in the old compressor and new accumulator?

The catch is that the system has been open to atmosphere for a few years and I believe the compressor may be shot. It had zero mineral oil in it when I pulled the drain plug. So, if I find this compressor is shot and order a new one, I want to make sure I don't have to flush the system again.

I am going to flush out the condensor and evaporator with some HCFC 147B. I am also going to replace the accumulator along with the orifice tube once I verify no leaks under vacuum.

 

[nuclearlemon]

ester oil. if there are any traces of mineral oil in the system, the ester will mix with it, the pag won't. ester works for both r12 and r134

 

[John Smith]

ester oil. if there are any traces of mineral oil in the system, the ester will mix with it, the pag won't. ester works for both r12 and r134

How do you feel about the new DEC PAG oil, that supposedly is compatible with any mineral that may be left in the system? Do you know if most new compressors are shipped dry? My worry is, I put ester in my old compressor, find out it is trash. Then have to flush the system and replace the accumulator and orifice tube again if the new compressors all come with PAG in them. Also, do you know if there is any issue running an "extreme climate" orifice tube in sub 105 degree temperatures? I read online that it can help regain some of the efficiency lost due to the conversion.

 

[Michael Hanson]

Live flush.but not the expansion valve,new reciever-dryer,new green o rings, vacuum at least 1 hour.POly-glycol oil,Really should change out the pressure valves and expansion valve. Mike

 

[nuclearlemon]

don't know about the dec pag, haven't heard of it, but i'm not in the biz. most compressors are shipped with oils in them.

if you go poly glycol (pag), then like michaelhanson says, you will have to replace every seal as pag will eat the old seal (and don't spill it on painted surfaces). a reason ester is still around...most people don't want to tear into their dashes to get the seals at the evap core

 

[John Smith]

Update. I flushed out the system. Replaced the orifice tube, expansion valve, and accumulator / receiver dryer. Filled the old compressor with 10 oz of ester. Pulled vacuum for a half hour and had no leaks. Yea!

That was short lived. This truck came to me with the compressor sitting in the back seat. It had no oil in it whatsoever. I figured the compressor was toast but I figured I would try it out to save some money. Well, it was running like a champ during my charging and I was getting nice cold air from the vents when the compressor started spewing oil and freon out the rear seal. Hmm, this would explain why the steering shaft was well lubed in oil when I received the truck.

Fast forward to today. I received my new reman compressor and it is prefilled with dec PAG. So, can I just drain out the compressor and fill with 10oz of ester and I'm good to go? The flush can said not to use it on the compressor, so I am leery of doing that. Dec pag is "supposed" to be compatible with residual mineral oil and ester.

Do you think I will be fine with a drain of the Dec Pag and a refill with Ester of do I need to flush the compressor to remove all the Dec Pag?

 

[John Smith]

So an update. I ended up draining the Dec pag and filled the new compressor with ester. Pulled vacuum, charged, and had ice cold air just in time for Fall. Fast forward to today. I noticed a small puddle under the truck and found lime green dyed oil on the compressor fan belt and pulley. The front seal must be shot on my less that a year old Everco rebuilt compressor from Autozone. Which of course is out of the super short 3 month warranty.

I kept my old compressor and am going to try to swap the front seal from the old one to the new. I wonder if they failed to replace the front seal during the rebuild?