tdatk944+S4

My A/C is out and I do not want to go through the expense of R12 repairs. Has anyone done the R134a conversion and what issues did you have if any?
Also where did you purchase it from.
Thanks in advance for your replies.

Tim

MityMse

I purchased the complete unit to convert to R134, the cost was about 700.00, I will get the exact cost if you want to proceed. It doesn't cool too well here in Arizona but, we all know that could be other problems and not the unit. However, I spend a total of 1300.00 and still don't have cool air.

ZC Wilson

ViribusUnits

I recharged with "freeze 12".

I know it's not "recomended" by whoever recomends this sort of thing, but it works for me so far, and it beat the heck out of the work and cost of converting to 134a. Becareful with the oil though. The freeze 12 stuff need the newer PAG stuff. Also, be careful with the connections.

Anyways, good luck.

P928sfan

I changed over to 134 when I had to have the compressor rebuilt. Told the rebuild shop of the plan, changed the drier, and blew out the rest of the system w/compressed air. Then reassembled. System has worked pretty good for about a year now. However, like the other AZ poster, Phoenix in the heat of summer (115), plus the black leather interior, builds up some incredible temps and it takes a bit to start making a dent in temp.

85S auto

Incendier

Be careful with the Freeze 12 and other Pep Boys drop-in kits. Freeze 12 is 80% 134a and 20% 142b to bring it to R-12 specs - for the most part, you're still introducing 134a to a R-12 system. As a side caution - some other aftermarket refrigerant replacements are full of propane, butane, or other HCs, which make great refrigerants as well as great pipe bombs.

It's not "recommended" because mixing R-12 and R-134a creates a mixture with a higher boiling point than either alone, lowering the effectiveness of the system. Also, R-12 seals and oil are not compatible with R-134a.

Unless the system was completely recovered - leaking the refrigerant to atmosphere isn't enough - sucked to a vacuum, resealed, correct fittings added, receiver/dryer replaced, and oil exchanged - it's both asking for long-term trouble and illegal.

Dozman

MityMse,

If the compressor, orings and the charge were installed correctly. I would clean the evaporator coil, condensor coil. You might have a TXV that is plugged or gummed up. The charge could also be off.

You should check the temp at the center vent after the a/c has run for 20 minutes.

tresamore

I drained my compressor of old oil and went to Wal Mart and bought the 134a kit for $29.95 and put it in. That was 2 yrs ago and it works fine. I did the same thing in my truck 4 yrs ago and its fine. My wifes Audi was fine for 3 yrs and we sold it. My friends Toyota has been 5 yrs w/o a problem.

Greg86andahalf

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> The freeze 12 stuff need the newer PAG stuff </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">PAG and mineral oil (R12 oil) should not be mixed. Even when draining and flushing the system, some residual mineral oil will remain. POE (ester oil) will mix with mineral oil. Ester should be used when converting R12 to R134.

I would not touch freeze 12. But if you look at the freeze 12 website, their oil charge kit is ester oil. That would be correct.

Greg
(34 degree vent temps with my self-renewed R12 system).

MikeN

You will have to pry R12 out of my VERY cold dead hands before I will change to 134a.

Last year I went through the whole A/C system replacing all O-rings, both expansion valves, and drier. Charged it up with R12, added some dye for any future leaks, and now have a system that is much colder then either of my "new" cars with 134a systems. It also cools down much faster then most 134a systems I have felt also.
Cost for all, about $350, with me doing all the
work (really simple)except for the evac and fill. Unless I have a major compressor failure, etc., it is still more cost effective for me to stay with R12 at this time. The trick is to not
let it escape once it's in there!

Greg86andahalf

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Unless I have a major compressor failure, etc., it is still more cost effective for me to stay with R12 at this time. The trick is to not
let it escape once it's in there! </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Mike you're right. Along with a bunch of other A/C work, I replaced my hoses with barrier hoses. I rebuilt my compressor with a $25 seal kit. I also have dye in the system. The "cool" thing is that the barrier hoses are needed for the 134 conversion anyway, so, if I someday decide to switch to R134 (doubtful, I have a couple of cases or R12 in the garage), the investment in staying R12 will pay off with R134.

Greg

dr bob

I changed my S4 to R134a a few years ago, after resealing, new hoses, oil replace, new drier, new expansion valves. Center vent temp is 21F(!) on 80F+ outside days at cruise speed, fan speed 2. It freezes your fingers on the wheel. Gotta fix that anti-freeze switch one of these days.

The FSM has a handy graph that shows R12 performance, and another that shows R-134a performance, at various ambient conditions. The 134a curves show better performance in the critical 85F to about 100F range.

My car arrived with 22k on the odo and a stack of receipts from dealers for AC leak check/evac/charge services. All with R-12. PO had it recharged for me before I took delivery, and it took a whole six months of SoCal "winter" driving to lose that charge too. I put some R-12 in it to get by for a while, and gathered the necessary bits for the conversion.

It tok me the best part of a day at tinkering speed, and got everything done easily. Vacuumed it overnight, charged in the morning. I missed an O-ring in the compressor manifold, and ended up fixing that, and another overnight evac/charge exercise. Since then, it has still dissipated some of the R-134a. Still plenty cold, but the sight glass has lots of bubbles instead of the light stream that resulted from the original charge (by weight). I put 1000g in the first time, vs the 1043g that the factory recommends for R-12 in that car.

As others have said, the key to a cold system is no leaks. After that, expansion valves, compressor performance, and the amount of air left in the system seem to make the biggest differences. Any air left in there makes the compressor work hard, loads the system down with extra heat on the high side, and raises the suction pressure and temperature (and therefore the evaporator temp) for no gain. Pull a good vacuum on a warm day, leave the pump attached overnight to get as much moisture boiled out as possible, and evacuate all your charge hoses so you don't inadvertently add more air back in during charging. Care in this area really pays off in cold evaporator temps.

Would I do it again with R-134a? Um, yes.

tdatk944+S4

Thanks for all the replies!
My system is definitely leaking as I used up my last supply of precious R12 on it last weekend and now the refrigerant is gone.If there is a weak spot in the system, where should I start and then I will probly go to the R134a stuff as it is available and still cheap. The compressor works fine as I had the system cooling last week with the R12 charge, but short lived. My drier does not have a sight glass , possibly PO had it changed. I know of a leak check with the dye stuff. Do you think that will reveal anything useful?

Tim

Greg86andahalf

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica"> I know of a leak check with the dye stuff. Do you think that will reveal anything useful? </font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Probably

MikeN

Kind of a mute point....sure it will show a leak or several. The problem is that there are 20 something O-rings in the system if you have rear air. You may find a leak at 2 or 3 of them, replace them, and in a week or two, more leaks
will crop up. In each case you leak freon, and have to open the system back up AGAIN to replace the bad O-ring. If you have to open the system up for ANY reason, and the 0-rings haven't been replaced in a while, go through and get them all along with anything else that is old or marginal.

Rich9928p

The two AZ posters talk about poor R134a performance. I can tell you that even with a good R12 system, Porsche's A/C can't cope with a heat soaked 928 and the AZ summer sun. There is too much glass and not enough cooling capacity ...

During the hot summer, the A/C on my '83 works very well AS LONG AS THE CAR ISN'T HEAT SOAKED. If parked in the shade, even on a 115F day it is OK cool in side. If the car is left in a lot and heats to 160F+ inside, it just won't cool down.

My '93 GTS came from the factory with 134a. It will blow very cool in the summer heat. But the dark Amazon Green color really pulls in heat (probably like a black car) so even with cold air blowing it doesn't cool down well. I'll run the front/rear A/C on long trips and can be comfortable, but it can take over an hour to cool the heat soaked car.

So, I don't think the R134a is to blame. It is the large amount of glass, the AZ HOT sun and an A/C system that can't cope with it. I now use car covers in the summer, it makes a big difference and helps save the paint and interior.