Tried this in the other forum but no luck. I am pulling apart my 92 f-150 ac system and converting to 134. It is my understanding that the old mineral oil is not compatible with the 134 and needs to be removed from the system and replaced with ester oil. I will pull and flush the hoses, evaporator and condensor and replace the accumulator/drier, o-rings and o-tube. But I am reading that you should not flush the compressor. So how should I get the oil out of it?

 

All that needs to be done is to pull a vacuum on the system for 30 min then put in your new oil. The 2 oils are compatible, othwerwise you would have to replace EVERY part in the system

 

Since you will never be able to get it all out, use the ester oil, it works with 134a freon and wont get gummed up by any trace amounts of mineral oil. What is making you convert? did you have a leak?

 

Blowing hot. Put the guages on and pressure was way low. Cost too much to repair and recharge r12 so decided to go ahead and convert since had to open it up anyway.

 

Thanks for the help!

 

You will want to isolate the leak or else it wont last. My point was if it was the compressor that was leaking, replace it, the dryer and get a 134a orifice tube, then you can run the regular PAG oil and it will perform exactly as it should. Not downing the ether oil, as you can see I drive a car they don't make parts for, my isuzu, and have had no trouble with ether oil. I'd replace the receiver drier as the old ones desicant may not work with 134 and the orifice tube, any o-rings you can get your hand on, as so you don't end up replacing them one at a time every time one meets demise to the different refrigerant/lubricant combo.

 

Just needs new seals. Most of them are in the o-tube. Which leads to my next question.....how the hell do you get the o-tube out? I got the liquid line off and pulled out all the chunks of old o-ring but now how do i get the o-tube to come out?

 

Well if enough is sticking out of the evaporator, pull it with a needle nose pliers, if not bend a coat hanger in to an "L" or "J" shape and use it to pull it out, if it breaks, there are some tools to pull it out.

 

Got it with the needle nose. DAMN! No wonder the ac wasnt working worth a damn. The o-tube was almost completely clogged.

Everything is flushed, blown out and put back together. Vacuuming it down now. Going to let it sit on -30 for about 30 min and then close the valves and go to bed. If its still sitting on -30 in the morning then i will go to church and thank God and then come home and charge her up. Thanks for the help.

 

Yeah, I can't tell you I've had some kid say oh I didn't replace it, can't be that important, and it never work right. Any time I ever pull one out, there's all kinds of metal shavings and a/c oil and nastyness. Glad to hear it worked out ok. About the only things that have ever given me trouble on these are the spring locks an the fittings.

 

You DO realize, that the 2 oils are NOT interchangable, right?

PAG Oil, is synthetic, and lighter, etc than Mineral Oil...

Plus, R-12, as a gas, is heavier than R-134a...

*By reusing the old R-12 system, you STAND to lose, up to 2 or more oz's of Freon, per year...


Also....When doing the conversion, is you so choose to actually keep the old R-12 hoses, etc....You SHOULD swap the compressors out..There ARE differences...


__________________________________________________ __________

*What is meant by this, is the fittings aren't as tight/formed the same, and as a lighter gas, the R-134a basically just slips through the cracks...

More or less...

Take it as you will; It is what it is...



As for my swap, I simply swapped the R-12 Low Port Fitting, for the R-134a one, and pulled the R-12 out (By questionable methods...Turns out, it was more or less gone anyways)...

And simply replaced it with R-134a...I now have cold air, and my compressor doesn't sound like a heifer in heat...

The whole thing was based on price, and cheapness...The compressor is on its' way out...So therefore, I don't actually care for it..

 

Yes sidewinder, i DO realize that the oils are NOT compatible. Thats why I asked the question. Its a $1,000 truck. Im not going to put $700 in parts on a $1,000 truck.

 

Two months ago I got my A/C working on my 89 F250. I only replaced the dryer and O-tube and the O-ring seals. Flushed out the entire system with ether(starting fluid, just make sure NO sparks are present or BOOM) even did the compressor as I didn't know what oil was in it.

I used PAG oil as it's the most common oil out in the "hand gernade" cans you get from the parts stores. After a 2 hour vacuum and no leaks. I have ice cubes coming from my vents!!!! The only thing I do notice is when you at a stop light, it doesnot cool down as good as R12 did. The reason for that is the condenser is not big enough for R134 to dump the heat out.


I have done this with all my vehicles and never had any issues.

 

Wasn't tossing that at you man...

 

Having worked in the industry and being regulated by the EPA, I have to say they're not compatible as well, but I've gotten cheap on a simple 134 conversion, ie: using ester, keeping the same compressor, maybe just changing a dryer and have had decent luck, replacing a o-ring here and there or a hose as they develop a leak. I've had better luck doing that than trying to keep on r12. Then again the difference between working on an f-series they made millions of and an Isuzu they only made 17,000 of, not all with air, is parts availability and cost effectivness.