A/C conversion

gmny · 02-05-2003, 05:34 PM

Hello,

I have a 91 325ic. Due to the expensive $$$ for R12 type freon, I want to convert the A/C to 134. I figure it must be cheaper than buying R12 every time the A/C gets low or needs recharging.

Is there any A/C parts I must switch out for this conversion (i.e., receiver/dryer, etc.) or can this be accomplished with simply the kit alone?

Thanks in advance.

Greg H.

Javier at Pelican Parts · 02-06-2003, 08:08 AM

I beleive the conversion kit consist of a new R/D and pressure switch, you will need to completly evacuate the system and replace all seals. I'll try and have a little more info for you later to day.

Jared at Pelican Parts · 02-06-2003, 08:42 AM

I have also heard that you have to change the condesor to a lagert one as 134a does not condense as well as R12. I have also heard of this stuff from Canada called Durcool whichis a refrigerant that supposedly will go right in the system without converting anything, although I havent seen anyone that has used it.

gott · 02-13-2003, 05:24 PM

gmny
This is way more complicated than discussed so far. To do it right, there are several considerations:
1. You must replace the R/D, pressure switch or switches on the R/D depending on which system you have and the TXV. The switches and TXV must be replaced because R134 has different heat characteristics than R-12 and the new ones operate differently. You will also have to put the adapters on the connections to allow for R-134 fill. You can usually get a kit for this.
2. The mineral oil used with R-12 is not compatible with R-134. You must therefore completely flush the system to get ALL of the oil out. This is not easy and there is not really an approved flushing solvent. The only approved way to flush is with R-12. In order to do this legally, you must have a reclaimation unit to do the flush.
3. You should not have to change the condensor, evap or compressor. When people first started doing conversions, it was thought that you had to change the seals. After a slew of conversions were done, it was determined that it is not required. If you convert to 134, the system will be less efficient because R12 has more heat capacity, but it will work.

If you are going to get the job done at a shop, it may be cheaper for them to just find the leak and fix it. You should not have to charge freon if the system is tight.

If you want to do it yourself, there are a couple of good automotive A/C sites to checkout. Try www.aircondition.com. I just completed a repair to my 89 325i that involved replacing a leaking evap and pressure switch and R/D. You can rent a vacuum pump (cost me $19/dayfor 1 day) and should buy some gages (can get cheap ones that will do for $60 at JC Whitney). To buy R-12, you need to be EPA 609 licensed. You can get your certification online for $20. It is an open book, online, multiple choice test and you can download the book at the site. If you normally make your own repairs and know your way around the car, you can probably do the A/C work. Mine cost me about $400 total to make repairs that were estimated at $1600 (although I thought they were on the high side).

My opinion, FWIW. I would not convert unless you had to. Go read about it at the site I mentioned.

--Gregg

gott · 02-13-2003, 05:40 PM

BTW, I would be very hesitant at using "drop-in" substitutes like Duracool. These producets are mixtures of different chemicals. Over time, the parts of the mixture differentially leak out of the system through porous components like hoses. This means that the characteristics of the refrigerent change over time and may become unsafe. Many of them contain flammable componenets like methane which are fine in the ratio of the original mixture, but may become unstable over time as the ratio changes.

--Gregg

gmny · 02-13-2003, 05:42 PM

Thanks for the info - I guess I'll figure out what to do after I add up the cost - need a/c though - even in a convertible - it gets really humid here in central VA. during mid August!! Again, thanks for the info.

Greg H.

pianodan · pianodan's Garage

I converted mine over to 134a last summer. I have a '86 and changed the dryer, flushed the system, pulled a vacuum, and charged it with 134. When the guages looked good, I unhooked the guages and everything worked like a champ.

Ran it all summer and I run it at least 30 minutes each month during the winter season. Mooey happy with it.

It was nearly empty of r12, so, with r12 over $50 a pound, seemed the right time for the conversion.

Dan