This weekend I converted my old R12 system to R134a in my 93 SC400. It works great now, blowing out as cold as 35 degrees. My old R12 had all leaked out. I think I did a pretty comprehensive and quality job. I did the following:
Pulled the compressor and dumped the 1 fl oz of old compressor oil (not much was in that thing)
I flushed the compressor with new compressor oil (called texaco 100 synthetic) - basically I poured a little of the new stuff into the low side port, spun the compressor by hand and dumped it out. I flushed thru about 2 fl oz.
Then added the 1 fl oz of compressor oil and remounted the compressor.
I took all the lines apart and blew them out with 100 psi compressor air, just to blow out any old refridgeerant and oil. Not much came out. I also blew the condensor well.
I replace all the o-rings in the lines with new r134a compatible o-rings that i bouhght at the lexus dealer.
With each o-ring, I treated the coupling with this weird gooy crap called Nylog, which is sort of like RTV/formagasket that super seals each oring. It stays gooy, doesn't get solid.
I rep[laced the dryer/accumulator
Tightened everything up./
Then I drew a vacum on the whole system for over an hour. There's a real good rental place in Austin that has a dang-good vacum pump. The pump maintained over 30 in/hg very effectively. This is an important process, as it gets all the air and moisture out of the system. Then I added the r134a. I probably put 3 cans in. I added just enough refrigerant so that the bubbles in the sight glass just went away.

All in all it was a very gratifying endeavor.

I bought all my stuff from a place in phoenix called www.ackits.com

 

how did you find out where there leak was?

I just had it converted from R12 to R134 also.
$150 for conversion + freedon and dye test
$110 for A/C condenser used with warranty
$80 re-recharge freeon.

so everything cost me $340.....

 

Frank.

Good deal on the AC recharge. I have not crossed that "bridge" yet, but know it is comming some day. I am a bit worried that the 134 won't be as chilly (efficient) as the R12, as that is what I was told, but sound like you have proven that incorrect. I find your information helpul for us who are true "gear heads", and not just looking for the, as I like to say. "glue on upgrades".

BTW,
I am waiting for the "bolt buster" tools to get in before I start the timing belt project. Should be here today. I ahev ordered evert stinking part in the front, as I do not want to tear this down again soon.

Take care,
928

 

I never did find the r12 leak, but I did pour some dye into the compressor and found a leak that I had caused. On the bottom of the compresosr there's a small meatal screw-on plate with a wire hanging out. I had loosened those screws in an effort to get the compressor out. (i really did not need to take it off - the wire went to a connector). After I ran the compressor and was doing the leak check with the UV light (pep boys, $32.oo) I found oil dripping from that plate. Needless to say I got that bad boy tightened back up.

I think I have spent about $230 doing this job, which included a 3-house manifold guage and leak test light, which are good tools to have, esp in Texas.

I had looked at getting a replacement condensor, but I think the type on my car was already designed for R134a, as it is more "substantive" than mere tubes and fins. I saw a diagram on the internet that descibed the type of condensor that mine is: each "tube" that runs laterally across the condessor is actually several small tubes, so that there is a great deal of heat being exchanged.

The R134a is not as chilly. the R12 would consistantly produce temps at 33 defrees F.

I gotta tell ya'll - I'm real glad I got that A/C fixed. I'm a salesman and I do a lot of windshield time. It's starting to get warm here.

OBTW: good luck on your TB, etc. The manual says to take everything off. All I took off was the coolant resivour and the upper radiator hose. The lower radiator hose I took the upper end loose and zip tied it to the pwr steering resivour. I had also put the front end up on jack stands too. When you get every thing off, set the engine to TDC on no.1, or as close to it as possible, just in case. The belt I got at lexus had marks to indicate where the belt went around the crank gear and each cam gear. It was a VERY nice thing. You'll totally understand when you get there and you'll thank the Lord!

If you're going to change the water pump, you'll really benefit from a dead blow hammer (it's a p[lastic mallet filled with buckshot). The water neck that the thermostat fits into is glued onto the waterpump outlet. You gatta bang the fire out of it to get it off. Also, the water pump is glued to the front of the bloclk., I used a screw driver to wedge in between and the hammer to pry (gentlY) the pump off of the block. There will be a lot of old black golue left on the surface of the block. The way I cleaned it off was to use a razor blade scaper tool that they use to take your safety inspection sticker off with. I also used a can of carb clearer spray (tolulene) to cut thru that crap. You basically want to prep the block surface as much as possible before you glue your new water pump on.

 

Frank,
Yeah, I have a dead-blow hammer, and used it many of times. Another one of those tools you can get at Harbor Frieght (AKA Disposible tool supply). I purchased all the (water pump and inlet housing) "O" rings and a tube of the proper adhesive from Carson Toyota. The Service manual is pretty clear on how to apply the goo (adhesive/sealent). I imagine it is similar to the stuff I bought for the tranny pan. I have since found that you can buy an aftermarket gasket for the trans pan, so I won't use that black goo for that, as I am afraid a chunk will fall off inside.

Glad you tipped me off on the compressor. I would have more than likey done the same thing... and although I prefer R12, and can get in "south O the border", I would not want to deal with it unless I had to. I have heard "horror" stories about them swapping propane in the R12 cylinders. Apparently propane makes a good refrigerent, until it leaks.

Anyway, I appreciate the update. The good news my garage (where my car stays, not a repair garage) is well equiped, and I have a full set of air tools (remember, I have a 928 which has it's own set of tricks you have to learn to work on it, including the NINE volume service manuals). If I have to, I can use the handle on my floor jack as a cheater at the end of the breaker bar when the tool gets here to hold the crank. I am tempted to change the front oil seal, as I purchased it as well, but looking at the crank gear, it may not be easy to pull that off. The shop manual would have you believe that all this crap needs to come off. I don't see how unless a seal change was in order.

Again, thanks for the tips. It all helps.

928

 

Did the deed today, ended up costing me $571.87. one of the main hoses was serverly leaking and 3 o rings were bad. parts total was 263.24 and labor was 276.26. It blows at 41 degrees now.
They did not replace the hose but they repaired it that alone in was $117, i didn't get hosed on the hose did i?

 

its 134a not R134a, isnt it? i have a 92, when i got the car the AC did not work, my ac comp was frozen, i slapped a new one on and recharged it with R12 and works perfect.

you can still get R12, its just more expencive, but R12 does blow colder that 134a thats why a lot of people (like me) rather pay a lil more and stick with the R12

R12 is like $45-50 a lb, im dont remember what the 134A is, but its dirt cheap.

you can convert your R12 to 134a and it isnt really that expensive, and its less expencive in the long run. but when you do the retrofit from R12 to 134a it doesnt seem to come out as cold, there are exceptions.

did yours come out as cold as it did with the R12?