R-134 Conversion - Looking for opinions

[Rob Mayercik]

Hey all,

The A/C on my '92 finally quit on me last weekend (or, at least that's when I discovered it had quit)

I have been able to determine that the compressor clutch and the associated relay in the power distribution center are both ok, so it's looking like the "low pressure switch" is interrupting the power feed to the compressor clutch. According to the FSM, that switch (located on the "left" side of the condenser, though I'm not sure whose left they mean - theirs, mine, or the XJ's :D ) goes to an open state when there's insufficient refrigerant charge in the system.

As a result, I'm going to have to take it to someone to find the leak and fix it. That's where my question comes in.

By now, several of you must have converted their XJ's R-12 system to R-134, so I'd like to hear how it works post-convert. My mother's '91 shadow has had this conversion done, and in my mind, the jury's still out as to how well it works. I think it's ok, but I don't spend much time in her car. Also, since it's the only vehicle I've ever been in that has had this conversion performed, my sample set isn't very large.

All opinions are welcome.

TIA,

Rob

P.S. Before I forget, has anyone ever heard of the afore-mentioned low-pressure switch failing?

[Eagle]

I'm in the same situation, with both the '88 XJ and an '88 MJ. I had the XJ recharged with R-12 a couple of years ago when this happened, and just a recharge was expensive. I had already decided that if there was a next time I would convert.

All my tech friends tell me that the conversion is easy but that I should replace the drier (they don't tell you that in the kits), so I have a new drier in the box waiting to go in. All the articles I've seen say that RC-134 doesn't cool as well as R-12, but I've also had people tell me their system cools better after the conversion than before. I don't know what to expect, but I'm gonna do it and find out.

[AZ Jeff]

As far as conversions go, there is an entire website devoted to a forum on this topic. Unfortunately, I lost the link, but I did hang out there for a while. Here is what I discovered by lurking there for a few months:

1. R134a and R12 cannot be mixed in the same system. One must remove ALL the R12 before installing R134a.
2. The compressor oil used in R12 system is NOT compatible with R134a. To convert to R134a, ALL the R12 oil must be drained/evacuated, and replaced with an R134a compatible oil.
3. The receiver/dryer should be replaced when converting to R134a.
4. Expect lesser cooling performance, as the components in an R134a system are sized larger to compensate for lesser capacity of R134a to dump heat. Losses should be on the order of 10%.

If you live in places like AZ (where I do), that may be enough to say "NO" to conversion.

If, however, you live in more temperate areas, plan to evacuate the system, drain the compressor of oil and refill, replace the reciever/dryer, and refill with new R134a. It's a good 4 hour job, if you have a refrigeration guage/manifold set and a vacuum pump.

[RINGKONG]

Originally posted by AZ Jeff
As far as conversions go, there is an entire website devoted to a forum on this topic. Unfortunately, I lost the link, but I did hang out there for a while. Here is what I discovered by lurking there for a few months:

1. R134a and R12 cannot be mixed in the same system. One must remove ALL the R12 before installing R134a.
2. The compressor oil used in R12 system is NOT compatible with R134a. To convert to R134a, ALL the R12 oil must be drained/evacuated, and replaced with an R134a compatible oil.
3. The receiver/dryer should be replaced when converting to R134a.
4. Expect lesser cooling performance, as the components in an R134a system are sized larger to compensate for lesser capacity of R134a to dump heat. Losses should be on the order of 10%.

If you live in places like AZ (where I do), that may be enough to say "NO" to conversion.

If, however, you live in more temperate areas, plan to evacuate the system, drain the compressor of oil and refill, replace the reciever/dryer, and refill with new R134a. It's a good 4 hour job, if you have a refrigeration guage/manifold set and a vacuum pump.

Or you could do what I did, in My 88 f150 and 87 cherokee..

evacuate the r12(almost until it stops hissing but not after) and put in the kit that comes with oil...

total time: 5 minutes... Total cost for Kit: 34 bucks

Don't tell the EPA though.. and you may create hydrochloric acid in your system .... eventually... way down the road... I have been running the converted 88 f150 for 2 years.. no problems or acid.. :D

ONLY do this if you take "Happy Go lucky" attitude with your non essential mechanicals, such as A/C( I.E if it breaks 3 yrs down the road, then so what.. :) )

[Rob Mayercik]

Good info so far - thanks, and keep it coming!

I'm pretty much decided on having the 134 conversion done anyway, so I'm more or less looking for info on what to expect.

AZ Jeff, I appreciate the steps you listed, but I think this job's out of my league. Seeing as I don't know where the leak is (and I don't exactly have copious amounts of time handy), I'll be contacting a local shop to handle it for me.

Rob

[t bell]

Let's see, in 2001 I had my R12 system recharged and I think it was about $125. The next year it wasn't cooling good at all and I took it back and had it converted for about the same amount of money. It turns out that my '91 now actually cools alot better. And I don't have to pay $45 for a can of R12. My mechanic told me that the actual temperature increase or decrease varies with different makes. But he told me that mine would cool better because of the system I had. Don't ask me what that meant but it was true. And also, I didn't replace my dryer. He evacuated the system for about 30 minutes. I thought the 134A was going to be a pain but it worked out pretty well.

[sidriptide]

well im going to do the big conversion today.. didnt get to it yesterday.... the system doesnt cool very well right now so anything will be an improvement.. i'll let ya know tommorow.....
mike
ps.... dont leave any cans of R134 in your truck in the sun for ANY amount of time... i wasted two cans when i left it in the truck overnight saturday and they only got 2 hrs of sun.. yes i know i'm a moron..

[Eagle]

Originally posted by AZ Jeff
2. The compressor oil used in R12 system is NOT compatible with R134a. To convert to R134a, ALL the R12 oil must be drained/evacuated, and replaced with an R134a compatible oil.

I think the conversion kits claim their oil is compatible but, if I wanted to play it safe, how do I go about getting the old oil out of the compressor? Can it be done in place, or do I have to remove the compressor from the vehicle?

[Rev Den]

Correct me if I'm wrong...but, the oil has circulated around the system for how many years? and you are thinking it's only in the compressor? If the oil is truley not compatable you wuld need to replace everything from compressor, condenser, evaporater, lines, hoses, valves, etc.....

Rev

[AZ Jeff]

When the system is off, about 90% of the oil is located in either the compressor, or the reciever dryer, according to what most experts say. Hence the reason to DRAIN the compressor of oil (by removing and draining on the bench), and replacing the receiver/dryer.

The really anal types say you should FLUSH the system with an appropriate flushing agent (which I am not certain what that is). That's supposed to get rid of 100% of the residual R12 type oil.

The point of my earlier comments is that, to do a fully effective conversion, it's more than just a matter of vent the old R12 stuff, and pump in some R134a. You really need to prepare the system correctly, and it can be expensive/time consuming to make the conversion properly.

This may not be a big deal to those who use AC infrequently, but I use it about 8 months of the year here in AZ, and I need a system that is reliable and efficient.

For R12 systems that are still pretty stable, conversion to R134a is probably not worth the effort. Now if your condenser takes the dive, or compressor craps out, NOW it makes sense to take the plunge and convert, as you are already talking big $ and effort to just repair the system.

[sidriptide]

the compressor low-side port where you need to charge the system is too close to the high-side hose and the fill hose quick connect will not fit ..... i need to get a 90 degree AN fiting to connect the inlet adapter, gotta wait one more day to see how it works.... its a trail rig for me so i am not overly concerned with "doing it right" thank god the 99 is already a R134 system..

mike

[RaiderXJ]

Originally posted by RINGKONG
Or you could do what I did, in My 88 f150 and 87 cherokee..

evacuate the r12(almost until it stops hissing but not after) and put in the kit that comes with oil...

total time: 5 minutes... Total cost for Kit: 34 bucks

Don't tell the EPA though.. and you may create hydrochloric acid in your system .... eventually... way down the road... I have been running the converted 88 f150 for 2 years.. no problems or acid.. :D

ONLY do this if you take "Happy Go lucky" attitude with your non essential mechanicals, such as A/C( I.E if it breaks 3 yrs down the road, then so what.. :) )

Is this the kit that comes with adapter fittings for the low-side and high side? I bought a kit for my wife's car yesterday to fill her A/C and it came with the fittings for a r-12 system and the instructions said that all you needed to do for a r-12 system was to evacuate the r-12, install the adapter fittings, and fill with the r-134a. The cans of r-134 had the oil and leak sealer in the can with the refrigerant. Is it really that easy to do a swap?

[RINGKONG]

Originally posted by RaiderXJ
Is this the kit that comes with adapter fittings for the low-side and high side? I bought a kit for my wife's car yesterday to fill her A/C and it came with the fittings for a r-12 system and the instructions said that all you needed to do for a r-12 system was to evacuate the r-12, install the adapter fittings, and fill with the r-134a. The cans of r-134 had the oil and leak sealer in the can with the refrigerant. Is it really that easy to do a swap?

Yes... that simple. and that was the kit.

Word of caution:

If you buy it for a Cherokee.. the "Suck" and "Blow" ports are to close together on the compressor, so that the fill hose will not fit on the "Suck" port. You have to find a fill hose with the brass ends and not the new one with the big black plastic end. They changed the hose in the kit... good thing I still had the old one.


:D

[Lucas]

I switched and my AC performance is great. Noticeably better than the original setup. Its been in the mid 80s around here and very humid. On Bi-lev, the fan switch in the middle, and the temp switch slid all the way over to the left, its literally too cold inside the jeep.

[HossHoffer]

You have to find a fill hose with the brass ends and not the new one with the big black plastic end. They changed the hose in the kit... good thing I still had the old one.

Good advice. I just bought a kit. I had new fittings and a recharge hose with a pressure gauge in it. The hose is crap as it took me 2 hours to get 1 and 1/2 cans of R134a in it. Went back and traded for a new hose and same thing. Gave up and took it to a garage. Came back charged it 15 minutes. Works great now but then it wasn't working at all before.

[sidriptide]

i did my change over today, and i had the kit with the black q/connect.. after argueing with the clown at pepboys about the hydrochloric acid issue, he told me i wont find a 90 degree addapter for the lo-side cause no one makes one.... A-HOLE!!! went to the local NAPA and he had one exactly for a conversion kit.. $12.00 and i now have cold air.. i would like it to be colder but i will take it as it is for now , it probably needs the evaporator coils cleaned.. i wont tell how i "evacuated" the system..
easy mod and its worth doing just to make your life easier.. keep in mind this is my trail rig so i dont really care much about the "acid issue" however serious it my turn out to be.. i need a/c cause my power windows still dont work...
good luck!
mike

[RINGKONG]

Originally posted by sidriptide
i did my change over today, and i had the kit with the black q/connect.. after argueing with the clown at pepboys about the hydrochloric acid issue, he told me i wont find a 90 degree addapter for the lo-side cause no one makes one.... A-HOLE!!! went to the local NAPA and he had one exactly for a conversion kit.. $12.00 and i now have cold air.. i would like it to be colder but i will take it as it is for now , it probably needs the evaporator coils cleaned.. i wont tell how i "evacuated" the system..
easy mod and its worth doing just to make your life easier.. keep in mind this is my trail rig so i dont really care much about the "acid issue" however serious it my turn out to be.. i need a/c cause my power windows still dont work...
good luck!
mike

The acid issue just bothers those anal rententive types.... I hate it when parts "people" argue with you, just take my money and give me my parts..... I have been forever banned from a Oriely's Autoparts near my house because of this... :D

Don't worry about the "World Ending Acid production" :D.

[sidriptide]

i wont go to pep boys anymore unless my life really really depends on it.. he is a typical "knows-evry-damn-thing-and-you-don't" kinda guy.. last time i was there i remember hearing him argue with another guy about brass fittings on brake systems.... i'm like... "lighten up you're just a parts guy" he didnt like that... i also made him a name tag on a postit "MR goodpliers"
i dont thibnk i am welcome back there. darn...
mike

[yellowxj]

Hell the hose on my ac had spun loose at the compressor. Dont know how. Its not the first time my system has been open. Dont forget to check the oil in the compressor. There is a fill port on the top. Dont know how much oil is supposed to be in there. Like crank case oil for the compressor. Just tightend my compressor lines and pumped in the 134 and a can of oil.
44 deg. in florida.

[Larry A.]

I did a successful 134a conversion on my VW van. I put in a new receiver-dryer, disconnected and dismounted the compressor so that I could drain as much of the old oil as possible, and used new O-rings at all the joints I had opened.
I put in ester oil which is said to dissolve the remaining mineral oil to make it compatible with the 134a.
I used a real vacuum pump and gauge set and pumped it down for at least an hour. Added 134a until I got reasonable pressures and the compressor cycled and cooled OK. It works pretty well.
On one of our XJs and our Saab 900, I took the quick and dirty route and used ES-12 propane/butane blend.
This is controversial because of its flammabillity and marginal legality in most states. It works well and there is no oil compatibility problem, but you have to buy it by mail and DIY.

[Hawaiian Style]

Hi,

When I bought my 88 Chief the AC was inop. A trip to WalMart and about 30 bucks was what it cost to convert it over. The R12 had already leaked out log ago and I just added the contents of the new kit. No flush or draining. I know it's not the "right" way but two years later (two hot summers) it's still cooling just fine. It still leaked a little so I bought some of the "leak stop" formula and that seems to be holding just fine.

Just thought you might be interested to hear another R134 conversion story. (BTW my system was empty of R12 when I added the 134 so the EPA stuff really didn't matter, if you still have some R12 then it would be illegal to simply open up a valve and dump it)

I am about a 3 on a mechanic scale of 1-10 so take my experience for what it's worth ;)

[txlen]

ok..ok..i'm a mechanic at dodge here for 23 yrs..there is a drop in replacement freon available called freeze-12, and ya don't have to do anything...and it's still good and cold....134a is alot different, ya gotta reduce the amount of freon in the system by 15%or so...the oils are not compatible with each other...if you have a copper or brass condenser it will not be as cold as if ya have a aluminum condenser..it gets rid of the heat better and your hi-side press will not climb as high...so..thats something to think about guys.....thanks..Len

[Backdraft]

Originally posted by txlen
ok..ok..i'm a mechanic at dodge here for 23 yrs..there is a drop in replacement freon available called freeze-12, and ya don't have to do anything...and it's still good and cold....134a is alot different, ya gotta reduce the amount of freon in the system by 15%or so...the oils are not compatible with each other...if you have a copper or brass condenser it will not be as cold as if ya have a aluminum condenser..it gets rid of the heat better and your hi-side press will not climb as high...so..thats something to think about guys.....thanks..Len

THANK YOU!!!!.........I knew someone would pipe up about the freeze-12. From what I remember it is a blend of 12 and 134 and does work wonders as a drop in replacement. I did it on an 85 ford 1 ton a few years ago and the thing still cools very good. I didnt want to say anything about it before because i couldnt remember all the ins and outs of it as txlen described.

Mike

[dusterboy71]

lost about 6 degrees of cooling in my '88XJ when changing drier and O rings plus putting in Walmart retro 134. Easy job. Cheaper if it leaks. I'll live with 44 degrees coming out my vents vs 38!