R12 to R134a Conversion

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ore0690
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R12 to R134a Conversion

Post by ore0690 » Sun May 29, 2005 5:29 am

About the A/C system conversion from R12 to R134a...

First, my current R12 A/C system is completely non-functioning. One good look at the grime-saturated exterior of my compressor and my rusty-brown condenser and you would swear every last trace of R12 refrigerant has leaked out naturally.

Having given the preceeding insight into the condition of my current A/C system, are evaporators known to leak? Moreover, are there any in-dash A/C components that should be replaced during a system conversion/revival (aside from possibly the evaporator,... any fittings, o-rings, etc.)?

Thank you.
-Oren.

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Post by T Type Dude » Mon May 30, 2005 6:48 am

In my old T Type I converted/retrofited if you say my AC from R112 to R134A. First off I took it to a shop and he tested me for any leaks, no leaks and my condensor kicked on but I was completely empty of freon(r112). So I went to K-Mart, bought the kit for $30 and bought two extra cans and just charged my AC. Keep the car running when you charge the AC and keep the AC ON. While its charging make sure to have someone feeling the AC making sure its coming out cold. After your done with the bottles let the car run for 10 minnutes and then you should be fine. I did it and worked great. Make sure your freon is empty, I've heard you can mix them and then I've heard its dangerous. Go to a local AC guy and just have him drained it if all else fails. Its not hard to do. Dont have to replace any seals or anything. Good Luck
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Tbird
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Post by Tbird » Tue Jun 28, 2005 8:16 pm

I gave in and got my 87 BLT converted last year at a GM dealership. I live in Canada and the rules are very stringent on R12 systems. Shoot we can't even buy R134a off the shelf here in Canada but our US counterparts can get it anywhere. I regress...
The dealership charged me about $300 CDN to do the job including putting a new accumulator and fittings. It was nice and cold for last summer but I found this summer it wasn't as cold. I had bought some extra 134a bottles in the USA that had the oil mixed with it. I also bought a kit that had a gauge (connects to low pressure side on accumulator) and can of 134a/oil, a valve and the hose/connector to connect the the system. I followed the easy instructions and topped it off. I ended up using an 11 oz can (7 oz of 134a, 3 oz oil and 1 oz leak gunk) of freon and got to the upper end in the good of the gauge. Nice and cold now. The refill cans are cheap and I bought the stuff at Walmart.

The reason the system will leak (most of the coversion will) is because the old systems were not designed to have the pressure used when using 134a. Also the 134a is a thinner substance (less dense) and will tend to leak around the orings in the system.

If you need more info just ask.

T
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Post by T » Wed Jun 29, 2005 12:58 am

It seems just about every shop or person says a different thing that you "have" to do.

Basically there are two problems with converting.

1. R12oil is not compatible with R134 PAG oil. Make sure all of the old oil is out of the system. That means blowing out or even flushing the lines and replacing components that can't be cleaned out. Lately I've head replacing the dryer(metal can at back of engine compartment) is a good idea, and they seem to be cheap($20). Never use PAG oil on a converted system. Use only ester(POE) oil.

2. The thing most people forget about is that the old stuff is gone for a reason. Most likely you have a leak. It could be many many things, the bigger the better. Two spots I would check first are the condenser(in front of the radiator) and the lines by the compressor. The curved one tends to develop a crack and eventually break in half. Using a dye can help find the leaks. NEVER use a stop leak type additive in the AC system, it will destroy your compressor.

-T
-T

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Post by Tbird » Wed Jun 29, 2005 3:46 am

Thanks T. I forgot to mentione that I had the GM dealership perge all the lines with a special A/C cleaning agent before putting the system back together. The accumulator was replaced on my system which I'm pretty sure some call a drier.

I didn't know about the leak stopper stuff being bad. I don't think they sell any cans of refills for 134a without it. I'll take a closer look next time I'm in the US of A.

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Post by luvgm » Wed Jun 29, 2005 6:41 am

The reason that you would need to replace the drier is because you have a leak or your system would still be charged. This will cause the drier to accumulate excessive amounts of moiusture when you hook the new system up and do not replace this with the oil and the o-rings that need replaced it works against you. If this does not get replaced with the rest of it, it will turn your 134 into a mild acid that will eat the ac system from the inside out. It usually takes one to two summers and then it will leave you hot and wondering what happened. I used to do ac systems in cars and that was one thing that we would have to fix because people were not replacing them when they would do the conversion. The thing that sucked about it was that people would then have alot more to replace then just a drier because the acid would eat at the whole system. That is why the Gm dealership flushed the whole system on Tbirds car.
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AC

Post by Rocketguy » Wed Jun 29, 2005 3:59 pm

My favorite mechanic told me the same: The 2 refrigerant oils are incompatible and if the old is not completely flushed out, the 2 oils will coagulate and cause failure, resulting in a more expensive repair than you probably needed in the first place. He recommends fixing and using the R-12 system if possible because of the cost of converting. Flushing out the old oil for a retrofit can lead as far as complete disassembly of the old system, and again, if you don't get all the old oil out the system will fail. Remember, if your system needs repair, just changing the refrigerants will not repair it. It still needs the repair it will just have different refrigerant. In my opinion, if you repair it, why not just reuse the R-12? I know it is more expensive but the conversion cost and potential long term problems resulting from it offset the cost.

I am no A/C pro, but I have been told a few times that you can not "read" how much coolant/charge is in a system with a gauge. The only way to tell how much Freon/charge is in a system is to suck all the Freon out and measure it. The only way to correctly charge it is to drain it completely and then ad the specified amount of refrigerant to the system. If you just start adding Freon to a system and accidentally overcharge it it could build excessive pressure and the system will purge some refrigerant out the safety valve (if your system has one), or worse, explode a line on the high pressure side. Very Dangerous!

My mechanic also told me that if you overheat your car the excessive heat can cause the A/C system to purge some of the Freon due to excessive pressure on the high side. I loaned my girlfriend my car once and when she gave it back the A/C did not blow as cold. Then I found out she overheated it and it had caused a purge of about a pound of R-12.
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Post by Tbird » Wed Jun 29, 2005 4:40 pm

Here in Canada no one (including dealerships and garages) can get R12 anymore. It is illegal for it to be sold/bought anywhere on the market. I had to bring my car to get fixed in the USA the last few times I needed repairs. It's a 3 hour trip to the border then another 3 to get home. Add the repair time and you've got a day wasted. Also if more parts are needed to originally planed you then need to spend the night which adds to the cost.

My conversion to R134a was a reluctant one and I waited for as long as I could before doing it. I researched for several weeks first. I found that everyone had their own ideas about the conversions and no 2 places had the same procedure. Even GM dealerships didn't have a set method between the dealerships. It made sense for me to purge the whle system and replace the accumulator (drier) while converting and I forced them to do it. Otherwise they would only have replaced the drier (at my dealership and not others) but I told them to clean it out with A/C cleaner first which they did.

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Post by T » Wed Jun 29, 2005 5:59 pm

R12 is available in the US, but only to licenced people, and then it is very expensive. I've converted several vehicles over the years, and my only problems have been leaks, which wouldn't help you with R12 either.
-T

'87 Lesabre T-type
L67 swap, CAI, STB, 180deg stat, Walbro 307 fuel pump, tranny cooler, Michelin XGT H4s, ZZP 3.4 MPS, AC 41-601 plugs.
PB: 14.447@95.08 (2.299 60ft.)

'88 Lesabre T-type
RIP

For questions concerning Lesabret.com, please e-mail me at lesabret@gmail.com

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