Returd

I stopped at an AC service joint today. Thankfully they were straight shooters.

Still had a R12 fitting at the rad (high pressure fitting?). Had a 134 fitting down by the compressor.

Did a nitrogen pressure test and found a leak at the passenger side shock tower. Couldn't find it specifically due to the ABS module being in the way. They suspected a leak at a connector partially visible under the ABS module. There's a connection there, maybe the leak is just a bad seal (fingers crossed)

I'm going to figure this out when I get home in a couple of weeks. The ABS module will have to get moved to get at the suspected leak site. I think I'm going to disassemble the same items on my parts car to learn how.

The shop owner speculated that someone did a back yard half **** job to the R12 system by simply recharging with 134.

He initially quoted me $500 ish to convert saying he'd have to pull the compressor, swap out the dryer behind the driver headlight (I may have that wrong) and all seals should be changed. The $500 was before finding the leak. After taking a look and finding the leak he said this could be a "can of worms" job and I was probably best to take care of once home.

Anyway a number of parts to come off for the conversion,

I'm thinking I'll do the parts swap myself when I get home and then bring to a local AC shop for charging. I can pull the compressor and bring it to a local shop for testing and swap out any of the other bits myself. This guy said he preferred using an ester lube over PAG and would normally add it to the compressor when out. I don't know the difference but he seemed to know his stuff and was straight up with me.

He mentioned another method of getting lube to the compressor but I didn't take notes. I will tomorrow when I return to get my rad.

I'd like to be able to do a pressure test at home, but don't have that equipment.

I there's a "how to" on this job here somewhere I'd appreciate a link.

Returd

https://www.clublexus.com/forums/performance-and-maintenance/735273-r12-vs-134a-a-c.html

https://www.clublexus.com/forums/performance-and-maintenance/293549-ac-conversion-r12-to-134a-3.html

http://www.nichols.nu/tip306.htm

https://www.clublexus.com/forums/per...tallation.html

https://www.clublexus.com/forums/performance-and-maintenance/294197-does-the-sc-have-an-a-c-system-diagnostic-check-come-on-fsm-folks.html

Returd

The more I read, the more I think I should swap all or as many system components as possible to items designed for 134. Changing the condenser and compressor shouldn't be too much grief, but the evaporator sounds like a headache.

I'm thinking of hunting down used 94+ components when I do this job.

suggestions?

RXRodger

iTrader: (2)

Don't do all of that, just change the drier, fix the leak, drain oil out of the compressor, pull a vacuum, and recharge it with 134 and oil. It's just a waste to do any more. The fact you have a leak under the ABS is probably just an oring on the EPC valve (I think I remembered that acronym, it's basically a pressure regulator for evaporator pressure). You don't have to remove any ABS components, it's just a pain to get to but it can be done because I have done it. The pain is worth not breaking into your ABS system.

Of course I am talking about an SC300 so maybe the SC400 is a little harder to get to so you may be SOL on getting at the leak like I can.

Returd

I do have to change a hose on my ABS (the accumulator to trac pump line is leaking) so moving the ABS may not be too much extra bother as I'll have to bleed anyway. That line is pretty much hemmed in by the passenger side cylinder bank and under the ABS unit. I can probably get a better look using a mirror but I'll be working by feel if changing a seal/oring. I'm thinking I'd better at least shift the ABS so I can make sure I get the seal in correctly.

Good info on the rest of the components though.

Too bad I'm doing the timing belt in Vancouver but won't get to the AC system until back home on the east coast. At least the fasters for the rad etc will come out easily the second time....

Sc400NL

i agree with RXroger , keep it simple
if it is leaking there it will be the connection to your evaporator , it's close at the fire wall
my R12 had een R134 retrofit , new oil in the compressor and a new dryer , total cost were about 200 to convert the system
my oem 25 year system doesn't have any leaks at all

Returd

Good info, thanks for the input. I'm going to try to get at the evaporator connection when i change the ABS line Ina few days. I won't be able to test but I suspect this will be one of the most difficult seals to get to.

While I have the rad out and am working on the timing belt I'm going to "break" all the compressor bolts/fasteners etc so I'll be able to remove it easily when I get home and change over the lube. I think I'm going to replace seals at all convenient connections but will leave the major components alone as suggested by you folks.

At the shop the tech said they would remove the compressor, swap seals and add lube to the compressor. I'm thinking I'll do the same prior to bringing it to a local (to my home) ac shop for pressure test and charge.

What i won't be able to do is a system flush as I've heard described. I'm getting a sense this is not necessary as long as I swap in a new dryer and get correct lube into the compressor.

I did observe at the AC shop the other day that when they threaded on the 134 fitting to the R12 connection at the radiator that the tech was putting some fluid or lube of some sort into the fitting before threading on. I'm familiar with thread sealant but this appeared to be something different, more like an oil.

Any ideas what this was?

Sc400NL

yes they add some oil into the system and you need a differend fitting , search youtube there are numerious examples
there is a section in the repair manuel about retrofitting R12 to R134a

Technical Service Bulletins TSB SC- 1st Gen (1992-2000) ... AC001-98 980403 A/C - System Retrofit from (R-12) to (R-134)

just bring it to a specialized shop and don't do it yourself if you don't know what you are doing , its mean stuff
let the ABS sits where it is , its not easy to bleed the system
i let it do at a normal automotive shop who has some knowlage about old airco systems and costed me only 200 to convert , my airco has sat still for at least 4 years before that
no compressor were moved i only replaced my evaporator a few mounts later because it had a small leak , refilled it and its running cold ever since


good luck , and as a advice ...buy the repair manuel on ebay , on a cd-rom if you don't want the paper one
it makes our hobby much easier

Returd

I replaced 2 o-rings at the expansion valve (nitrogen leak test showed a leak there) and replaced the dryer. I had the system charged, dye and lube added and it's now working.

As an aside, getting a dryer could be an issue. Considering they're only $20 I'm going to grab a replacement or two for future use as they may become unavailable.

Sc400NL

see?
now read your first post again , that would have cost you loads , and now a few O rings and a dryer , these systems are very well build
and those dryers ? you can use many types of Toyota dryers

Returd

Yep, good advice on here, fingers crossed no leaks develop. If they do I'll be much better prepared to deal.

pishta

where is this '92 assembly located, behind the glove box? This is a great pic. I think my expansion valve is not working as it wont get cool. I have 40-45 psi of R134 in it (retrofitted 10 years ago) when the pump is running but little to no cooling at the vents. When the pump is not running I see about 120 psi.