Coverting R12 to R134, who's happy?

[clavinZERO]

A few years ago, after my a/c system was wide open, I put in r134a. I installed a new receiver/drier and new o-rings at the reachable fittings. The compressor was my original from 1990. I added the update valves for the r134a and dropped some of that esther resin stuff that is supposed to lubricate the system or something (read the label for amounts, etc.). The system was then vacuumed down and recharged with the r134a. At idle this did not work as well as r12, but during cruising of any speed it blew 36/37 degrees through the vents on pretty warm days; I had a thermometer shoved into the dash vents to test the refreshed system.

Helpful hint: make sure both the speeds work on the auxilliary fan!! My resistor broke (for the low speed) and one day the a/c line blew a hole near the exhaust manifold. I am assuming this happened because the lack of cooling overheated the system and built up too much pressure.

[u3b3rg33k]

A few notes

I like to use something hydrocarbon based, ie R12a; I like duracool, and it's very effective, not to mention cheap (30lbs for under $190). HC refrigerants will accept M1 0w30 as lubrication, and be perfectly happy. R134a will not. Also, R134a is a horrible greenhouse gas. The CARB claims it's 1300x worse than CO2.

A working aux fan is an absolute must, regardless of what refrigerant you choose. the system creates a temperature differential between the condenser and the evaporator. the cooler you keep the condenser, the happier you'll be.

[91 318is]

A few years ago, after my a/c system was wide open, I put in r134a. I installed a new receiver/drier and new o-rings at the reachable fittings. The compressor was my original from 1990. I added the update valves for the r134a and dropped some of that esther resin stuff that is supposed to lubricate the system or something (read the label for amounts, etc.). The system was then vacuumed down and recharged with the r134a. At idle this did not work as well as r12, but during cruising of any speed it blew 36/37 degrees through the vents on pretty warm days; I had a thermometer shoved into the dash vents to test the refreshed system.

Helpful hint: make sure both the speeds work on the auxilliary fan!! My resistor broke (for the low speed) and one day the a/c line blew a hole near the exhaust manifold. I am assuming this happened because the lack of cooling overheated the system and built up too much pressure.

You know it's funny you say that because I found out today my aux fan isn't working, so I gotta fix that now. The A/C seemed to work decent when I'm riding down the highway, but as soon as I stopped, it would get warmer. Found out my fan isn't working.


Since we're on the subject, where is this resistor located?

[u3b3rg33k]

It's on the fan - and cooled by it. 85W, .5 ohm, IIRC. I'm planning on stepping up to an aftermarket fan controller, some day. For now, I just tossed a few old sealed beams into the battery tray, wired them up in parallel, and called them a low speed resistor.

WAY cheaper than a new resistor at dealer / e-tailer prices.

[clavinZERO]

You know it's funny you say that because I found out today my aux fan isn't working, so I gotta fix that now. The A/C seemed to work decent when I'm riding down the highway, but as soon as I stopped, it would get warmer. Found out my fan isn't working.


Since we're on the subject, where is this resistor located?

The resistor should be on bottom of fan, as you face it while standing in front of the car. It has a fat wire with a terminal screwed onto it on both the "in" and "out" sides. About $20-25 to replace.

[Jean]

It's on the fan - and cooled by it. 85W, .5 ohm, IIRC. I'm planning on stepping up to an aftermarket fan controller, some day. For now, I just tossed a few old sealed beams into the battery tray, wired them up in parallel, and called them a low speed resistor.

WAY cheaper than a new resistor at dealer / e-tailer prices.

instant/permanent engine bay light :)

But seriously, hit up a local electronics store, and you'll find a resistor of enough wattage and same resistance for a few bucks.

[torqueflight]

I put r134 in my r12 system because Im lazy, but it works. I just have to find the leak. That leak stop doesn't really work well. So far its been working for over a year and half. Im thinking of cleaning the system out and going with the freeze 12.

[91 318is]

Thanks guys.

I'll figure out the fan issue, but I plan on just converting it and be done. Hopefully it will get the job done. I have a buddy that works at a shop that can properly charge it so hopefully that will do the trick.

[Adrian_Visser]

A few notes

I like to use something hydrocarbon based, ie R12a; I like duracool, and it's very effective, not to mention cheap (30lbs for under $190). HC refrigerants will accept M1 0w30 as lubrication, and be perfectly happy. R134a will not. Also, R134a is a horrible greenhouse gas. The CARB claims it's 1300x worse than CO2.

A working aux fan is an absolute must, regardless of what refrigerant you choose. the system creates a temperature differential between the condenser and the evaporator. the cooler you keep the condenser, the happier you'll be.

R-12 is rated at 8100x worse global warming potential than CO2

[robmespeedy]

I have propane in mine, blows super cold.

[brandondan1]

R134 sucks in the TX heat, in stop and go traffic. If you're constantly going 30mph+ it offers sufficient cooling though.

If I had to do it all over again, I would've paid more to get the R12 refilled instead of converting.

[torqueflight]

Anyone know of a place in Los Angeles that still does R12?

[scottinAZ]

I was just about to do this, tracking down a new resistor is pointless. Thanks for the confirmation. Fuse 3, right?

Easy Peasy to do this. all I did was take the terminals and attach them ALL to one side of the resistor. This way, if you decide to re-attach the resistor for some reason, you dont have to worry about repairing the wiring. Takes 4 phillips screws and about 10 minutes (if they are stubborn) I also pulled fuse 18 (FAN HIGH SPEED) and replaced fuse 3 with a 30 amp unit (fan low speed) Its convenient that fuse 18 happens to be 30 amp. If I read the Bentley correctly, any time the fan is commanded on LOW, this will make it run on HIGH, so a HIGH command becomes redundant.

[91 318is]

Well I found the resistor and tested it and found it was burned up. So a new resistor and my aux fan's working and the A/C blows colder. I'm still up the air about converting it, as I already bought a drier and adapter fittings.

[joonsup]

i've seen some people sell r12 cans on craigslist at around 25 bucks a can (12-14oz each). How many cans would you need to recharge the a/c?