Considering an R12 to R134a retrofit

Yurick · 07-21-2008, 12:14 PM

I have a 1990 325iC (E30), whose air conditioner over the last few years had progressively blown warmer air. At the moment there is no cool air at all coming out. The compressor turns on like usual, but no cold air. I presume that there may be a small leak in the system somewhere and at this point the freon is all gone.

I am considering upgrading to the R134a system. Looking at the conversion kits our host has to offer (I find them confusing), because if I purchase a kit of sorts, then I would expect it to include all the items necessary for the upgrade. It seems that purchasing a kit, another kit has to be purchased as well to cover the necessary parts.

Has anyone had to upgrade their A/C system from R12 to R134a? Could you please shine some light on which components really need to be replaced/installed? Any recommended brand names? Expected price?

Thank you.

Manolito · 07-22-2008, 05:58 AM

Hopefully someone with some expertise will respond, but in the absence of actual knowledge, I just looked at the kit in the catalog that includes: new receiver drier, new O-rings, a capacity label, and a set of R134a valve adapters.

That kit, plus refrigerant, the proper oil, solvent to flush the old oil out of your system, and a vacuum pump to pump the air out before refilling, should work, but that is the absolute minimum parts you could change. The minimum requirement is that you have oil that is compatible with the refrigerant, and O rings that are compatible with the oil, and a new receiver dryer whenever you open your system.

Because R134a has different pressure/temperature characteristics, I would have expected to need to replace pressure sensors, the expansion valve, and possibly the compressor. That, however, would more than double the cost, so you would not want to do it unless it is truly necessary.

In general, an R134 conversion in an R12 system will not be as cold as an R12 system. With just this kit, I would expect it to be significantly less cold than the original R12 system. However, I have not tried it, so I am speculating here. It may be just fine.

Yurick · 07-22-2008, 12:22 PM

The new o-rings, are they for the compressor? Will the compressor need new seals as well?

Manolito · 07-23-2008, 06:24 AM

Sorry, my my knowledge is just theoretical, I have never installed one of these kits. I would expect that the O-rings are outside of the compressor, but I am not certain.

coolbear1 · 07-23-2008, 08:50 PM

I converted my 88 e30 cabro to 134A.
You should first find your leak.
I assume there must be some R-12 left or the compressor would not come on at all. Unless you are jumping the pressure control out.

If you can get ahold of an electronic leak detector, an R-12 leak is easyer to detect than if you replace it with R-134A, because of the ozone depleting clorine in it that you have heard so much about. This is a good reason to for the leak first.

There are several ways to approach a retofit to 134a.

Sometimes you can take shortcuts and get away with it. I would not. most of the time it will cost you more in the end.

I always recomend removing the compressor and draining the oil.
Some people don't, but the oil in it will not mix with 134a. Kindof like oil and water.
The problem with this is in an air conditioner, some of the oil circulates around the system with the refrigerant. If it will not mix, it can log up in the system somewhere, (usually the evaporator). It woun't return to the compressor in sufficient amounts and it will cause the evaporator to loose efficency.

The O rings in question, are in the refigerant line connections, Evaporator inlet, expansion valve connections and reciver drier connections.
They need to be replaced because they are not compatable with the refigerant and the new style oil.
The 134A will attack them and cause them to leak. So take the lines loose and flush them good with system flush. It is available in pressurised cans, It is basically synthetic oil and 134A, and wont harm anything if you don't get 100% of it out.

There is one also in the compressor shaft seal, But it is not feasible to change it in most cases.
It usually will last, at least as long as you might expect the compressor to last. Sometimes years.
But I have seen them go the day after a retrofit. Never know.
If it does start leaking you will have to get a compressor.

Flush the condenser and the evaporator coil also.

Also, 134A works at slightly different pressures, temperatures and velocities than R-12, so the expansion valve that meters the refigerant into the evaporator should be changed to a 134A valve.
.
You need to also install a new recever drier.
The POE and POL synthetic oils are very hygroscopic, (absorb water)and do not react will at all with moisture. Water will break down the compounds in the oil over time and you wil end up with something other than oil.

If you do these things,and pull a good vacuum, avoid air, and moisture contamination, you should end up with a system that will perform well for years, assuming your existing components are healthy.

Good luck.

Manolito · 07-24-2008, 05:39 AM

I was sort of hoping that CoolBear was going to show up and rescue me. I jumped into water over my head when I tried to respond to this one. Whew!

coolbear1 · 07-25-2008, 10:31 PM

I'm just living proof that the challenged can be usefull.

Yurick · 07-28-2008, 06:39 AM

Has anyone heard of or has any experience with the "Freeze 12" product? It is supposedly compatible with the R12 systems and would eliminate the need for R134a upgrade, which I am dreading.

coolbear1 · 07:34 PM

Have you tried calling around to some of the local automotive a/c shops to see if they have any R-12 still available.
Virgin R12 is not being manufactured or sold anymore, but recycled product is still available in limited quantities.
It is illegal to sell to anyone that is not liscensed, but they should be able to charge you up allot cheaper than you can retrofit your car.
That is unless you have a substantial leak, or other mechanical problem.

As for the Freeze 12 product, I just don't know enough about it to comment.

But, for more info, have you visited; http://www.freeze12.com/?

Manolito · 07-28-2008, 08:16 PM

I have about 22 lbs of virgin R12 in a cylinder in my garage, but I am a long way from Florida. I should have sold the stuff when it got up to $50 a pound. Not much demand for it any more.

I have heard of Freeze 12 working in unmodified systems, but I understand that you have to remove all the R12 and pump down the system to a vacuum before putting it in. I have never used it personally.

Yurick · 07-29-2008, 04:07 AM

Gents,
I appreciate all the input. I think I will go ahead and try this Freeze 12 refrigerant and see how it does for me.

coolbear1 · 07-29-2008, 08:00 AM

Please let us know how it goes.

Yurick · 07-29-2008, 10:39 AM

Will do.

Yurick · 08-25-2008, 05:26 AM

Well,
This past weekend, I buddy of mine helped me (he actually did all the work, while I was drinking beer) load my A/C system with Freeze 12 refrigerant. The system sucked up a small can of stop leak, 3x12oz Freeze 12 cans, but was still a little short (maybe another 1/2 can would do it). That was enough to give me cool air in the car, about 50F. I will have to pick up another can of Freeze 12 on eBay and top it off later.