pauli

I plan to retrofit the R12 a/c system in my '90 LS400 with R134a. Do I need to drain and/or flush the old mineral oil from the compressor before adding the 134a compatible oil? If so, how tough is it to pull the compressor?

nk1983

bump! anyone with any experience on this? I wanna know too...do the "conversion systems" which claim to do it instantly work? anyone tried it? anyone actually done a conversion?

nthach

If you are using a POE 100 oil like Castrol Ester or BVA Auto 100, just get as much of it out as possible. If you are using a PAG like ND Oil 8, you have to get all of it out, and flush out the lines/condenser/dryer.

And STAY AWAY from those conversion kits made by Interdynamics/Quest., they are LOADED with sealers and other addivtives that can destroy the system. I just did a retrofit to my car, i changed all the O-rings i can get to with OEM Toyota O-rings, installed a new dryer, added 10 oz(8 to compressor, 2 to dryer) of BVA Auto 100 to my system, and let an AC shop do the rest. I spent a bit under $200 for everything.

Check out www.ackits.com if you need parts or oil, sure they are not OEM Denso parts, but worlds better than the crap Kragen/AutoZone/Pep Boys carries for AC.

flkey

'03 LS430 COCOON
Is there not a performance penalty to go from R-12 to 134?
Automotive A/C systems are complicated and smallish, IMHO best left to professionals experienced
in these conversions. Look at it this way, I'll fix the potty for $10, but will leave a $1-2000 system to one who has all the facilities and faculties to address this repair or change.
What do you think? I mean why take the chance the system is improperly evacuated, oiled, and charged?
Your faithful adviser ;- )

Lexkost

The conversions don't work ...........Fix the leaks in your system and put R12 freon back in .....

buttons

Go to www.maxifrig.com for R12a

don't convert to anything else. $5. per pound---anyone can buy--colder than R134a---onlyuse 70% . Super stuff.... OH, you can use the oil in the compressor.NO new oil required. Have converted 4 cars and a van but not a Lexus {R134a in it}.

Kansas

After twelve years of ownership, my 90 LS was converted to R134a for about $200 around two years before I sold it. The conversion was done by a Lexus trained mechanic at an independent repair shop that specializes in Lexus.

I could not tell any difference in A/C performance with R134a except that (maybe) the fan ran at a little higher speed some of the time.

After the conversion to R134a, I remember idling the 90 LS in the KC Royals stadium parking lot for over one hour on the hottest day of the year - right at 100 degrees! The temperature gauge never rose above normal, the fan never ran very fast, and the A/C put out loads of cold air for my wife and I and the other couple in the car. And the surface temperature of the parking lot was probably around 120 degees.

I remember the above instance so well because I was going to the game with a friend that has a Mercedes E320. He was amazed that A/C at how my old LS A/C could put out so much cold air and that the car did not overheat.

nthach

same here. Stick with R-12 or R134a, don't use any sealers/cleaners/snake oil refrigerants, PLEASE think of the next owners of your car, and the mechanics who have to work on it. their machines cannot recover "alternative" refrigerants and they cannot handler sealers and cleaners without clogging up the machine's solenoids and filters(which cost big bucks by the way!)

LexLS

I have been using R134a for over a year now without any problems. It is amazing how fast my car cools down even on the hottest days, and as Kansas said, no overheating.

If anyone could actually explain how to charge up the A/C system and/or do the conversion I would also be interested.

pauli

Thanks for all the thoughtful replies. I'll let you know how the conversion works out.

nthach

if you are charging a system, you need a vacuum pump, manifold gauge set, charging hoses and valves, of you're a true tech, recovery machine. The gauges are important, since you need to use pressure readings to determine the right charge and see how the system is running.

an R-12>R-134 conversion done the RIGHT way, NO DIY kits, or at least in my opinion:
1. change dryer
2. change all o-rings you can get to
3. try to drain out as much oil as you can
4. flush out lines using paint thinner, brake cleaner can be used on removable lines
5. fill system with a GOOD quality POE oil, no aerosol charges! i used 10 oz of oil in mine, japanese makers tend to underspec oil fill amounts
6. install retrofit adapters
7. look up the system specs, and either buy/rent the equipment for an charge, or take it to an AC shop.

some cars do need the compressor/expansion device/condenser/evap changed out to R-134a compatible parts, and the dryer is a MUST-DO.

pauli

In regard to buttons' suggestion to use maxi-frig, I found the following notice on an EPA website:

"Flammable Refrigerants

The use of flammable refrigerants is not permitted.
Refrigerants sold under the names of 'Duracool 12a,' 'HC-12a,' 'OZ-12,' 'Envirosafe,' 'MaxiFrig,' and 'Permafreeze' are flammable refrigerants and are not EPA approved substitutes.
In addition, local fire codes often restrict the storage of flammable materials. Also federal, state, and local agencies may have regulations related to flammable refrigerants."

Maybe the EPA's overreacting to this, but thought it should be noted.

pauli

In regard to buttons' suggestion to use maxi-frig, I found the following notice on an EPA website:

"Flammable Refrigerants

The use of flammable refrigerants is not permitted.
Refrigerants sold under the names of 'Duracool 12a,' 'HC-12a,' 'OZ-12,' 'Envirosafe,' 'MaxiFrig,' and 'Permafreeze' are flammable refrigerants and are not EPA approved substitutes.
In addition, local fire codes often restrict the storage of flammable materials. Also federal, state, and local agencies may have regulations related to flammable refrigerants."

Maybe the EPA's overreacting to this, but thought it should be noted.

nthach

thinkof it this way: if you don't your car to become a fireball in a severe frontal collision, don't use HC refrigerants. the risks outweigh the benefits.

nthach

before anyone here goes to Kragen or Autozone for AC stuff, read this first!
http://www.motor.com/MAGAZINE/Pdf/042003_04.pdf