Automotive Air Conditioning Information Forum (Archives)

914lps on Thu June 27, 2013 7:51 PM

Year: 1991
Make: Lexus
Model: LS400
Refrigerant Type: R12
Country of Origin: United States

My A/C is out. I have a leak in the system. It is small, but I need
to fix it.

After researching I have decided to convert to 134A. My research was reading
posts online, and calling about 6 repair places in major cities to see what
they recommended I'm in a rural area.

So first I convert the system. Fill with 134a and then look for the
hard to find leak.

I took the car to my “regular” mechanic.
He is a good guy and is honest.
But I am the only customer around with a Lexus. In fact to find a guy that “works” on Lexus
day in and day out, it is a 150 mile trip. One way...

Anyway he is working on it. Or trying
to… His plane is to evacuate the system,
flush it, change the fittings, replace the dryer, etc, and then fill with 134a
and oil, and UV dye.

He is having a hard time figuring out how to get to the parts he needs to
get to as the Lexus routing of stuff is different. So I am looking for any diagrams or tutorials
I can find.

Anyone know of any????

If needed it is a1991 Lexus LS400.

I did some Googling and Bing'ing, and forum searches, but today just has not been my day.

In particular he needs any directions on retrofitting this A/C system, how
to get into the system. What of the four service ports are for what (which
ones does he connect to for charging, gauges flushing, and so on) , how to
flush the lines and drain compressor, best way to clean evaporator and dealing
with the expansion valve (replace it or clean it and how to clean) on the fire
wall.

In short the more info or how to the better.


I thank you folks for you kind help and understanding... I am glad I found this forum.



Oh I told him I would take my time to research it etc.. My time is cheeper then his....

iceman2555 on Fri June 28, 2013 12:57 PM

Locate the leak....repair the lean....recharge with R12. You will be happier in the long run.

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The strongest reason for the people to retain the right to keep and bear arms is, as a last resort, to protect themselves against tyranny in government.
Thomas Jefferson

NickD on Fri June 28, 2013 1:53 PM

Doing a search for shop manual, even used ones for you Lexus, running around 250 bucks. See alldata.com lists this vehicle. These are complicated vehicles, but you all ready know that.

To really be happy, would also require a parallel flow condenser.

Agree with iceman, stick with R-12.

94RX-7 on Fri June 28, 2013 3:21 PM

What, in your research, led you to conclude that converting it to R-134a is the correct answer?

Lexus/Nippondenso built a really nice system for the early LS and SC, and used at least one device that most mechanics aren't familiar with: an Evaporator Pressure Regulator. I don't know if the EPR is adjustable, but if it is, it should be adjusted for the correct pressure for R-134a.

I'm going to chime in with everyone else: keep it R-12 and get a factory shop manual.

NickD on Sat June 29, 2013 5:42 AM

Well if its a typical high end system like used on the Supra of this era, receiver with a sight glass, Denso compressor, thermostatically controlled compressor relay monitored at the evaporator, TXV, only uses about 28 ounces of R-12, and a climate control system that will blow your brain. Could only get manuals from Toyota for 250 bucks back in 1990 when prices were cheap. General, body, electrical, and and parts breakdown manual, set of four manuals. See the Lexus is about the same. Fan control could also blow your brain with components buried everywhere. Really need that component locator.

And has five computer systems all data linked together, all with built in self-diagnostics, that would wouldn't figure out in a million years how to use, without the aid of the shop manuals.

Cussboy on Sat June 29, 2013 1:54 PM

Quote
Originally posted by: NickD
D
Agree with iceman, stick with R-12.

Agree also. First of all, why would living in a rural area have anything to do with converting to R134a? Refrigerant is NOT consumed, so R-12 in a leak free system could last for the life of the Lexus. Have the guy add dye and/or use a sniffer and find and fix the leak, and to evacuate and add R-12. If he doesn't have equipment to do R-12 (possible), buy or rent vacuum pump and set of R-12 gauges, and add your own R-12, and you'll have the equipment and still save money and have better performance.

Or let the mechanic use the equipment you buy; most likely his vacuum pump will already have fittings for both R-12 and for R134a, so you won't need to get one. The basic systems are very similar from vehicle to vehicle, and I'll bet he's seen a ton of Toyotas.

Dougflas on Sat June 29, 2013 2:35 PM

I have info on that vehicle. I have the MACs cd series.

I am also in agreement to keep systems r12 ( especially since I have over 90 lbs of r12) Is the system completely flat? If so, put some r134in it and leak test it,fix the leak, and recharge with r12.

914lps on Sun June 30, 2013 2:47 PM

Not sure how to respond to some of the posts... But here goes..

First thank you.

I decided to go with the conversion due to the cost of r12, and estimates just for finding and fixing the r12, without converting it.

I called major AC automotive shops in Los Angeles Ca, and Las Vegas NV. I also called dealers and independent shops specializing in Lexus.

To keep the r12 I was told at 200.00 to 300.00 just to find the leak. Then what ever the cost was ti fix replace what was leaking, then at lest another 100.00 top off, and that was the cheepist r12 option I was given.

Most all said to just convert it. Including dealers.

And Lexus does have a set guideline for doing the conversion.

So I figured at least 300.00 + to keep the system with the unknown cost of living with a r12 system and what happens if it lacks again, or paying the low end estimate to convert of 250.00 +what ever the leak issue was. And then if I have an issue in the future I am dealing with cheep 134a

As for the evp valve yes the car has one, yes we know what it is. I did pay to us the Toyota Lexus online tech info (same as dealers have access to).

It give instructions for converting to 134a. It basicly ates to change fitting, evacuate and flush the system. And change out the reciver dryer, and put on a wartning lable. And that is what "we" planned to do.

But it does not state were or how to flush the sytem. The compresor does not have a iol reserve on it. So even though "we" removed the compresor the issue is were is it best to get into the lines to flush. Again Lexus's instructions do not tell how to flush.

I found lots of info on the tech site, but no directions on how to flush the lines/system.

A for a member here having 90lbs of r12. Good for you! But that does not mean I have it. Yes I can get it, For 60.00 to 80.00 per pound.

As for filling it with 134a finding and fixing the leak, then converting it back to r12. Well that adds a lot of labor. I first have to change fittings, and properly flush, then fix, then change fittings back to r12, and flush again etc... Not a good thing to be doing.

I have posted in a LS400 forum, and 99 percent said they are happy with the conversion they had done.

I have a 88 ford that was converted and an happy with it. I also had a 84 Saab that was converted and was happy with it.

So my remaining issue is with flushing the system. "We" are just trying to be sure on the how to of it, over taking a guess ant flushing it.

And I am happy that my mechanic is just making sure he flushes it the best way... Not just going with a should be OK to do it way.

If any of you know the document I need, I still have a paid for subscription for the next few days on the tech site.
https://techinfo.toyota.com

Not sure what the issue of a "a parallel flow condenser" is.. Can you explain more.

Living in a rural area does not effect the ability to get r12. It is around town, and it can be bought and shipped, etc... It does limit the availability of folk who can work on it and/or that I would trust to work on any car. Just like big cities we have shops here run by good guys and some by not so good guys.

To Dougflas, as you have the MACs CD could you possible check to see if they give detailed info on converting the system .. Especially flushing how to? If they do, and you can print or scan and email it to me, I would appreciate it. What would you charge to do that?

If I did not cover anyone's points, etc.. In my response.. Sorry about that..

Also I can't seem to find out how to subscribe to this posting so i get notified be email. I thought I had it set up in my profile. It looks like I did.. But must be missing it,,,

Also would anyone recommend a different area in the forum that might be a better place to post this???

Again I thank you all for responding...


Edited: Sun June 30, 2013 at 2:54 PM by 914lps

94RX-7 on Mon July 01, 2013 11:59 AM

Quote
As for filling it with 134a finding and fixing the leak, then converting it back to r12. Well that adds a lot of labor. I first have to change fittings, and properly flush, then fix, then change fittings back to r12, and flush again etc...

You put R-134a into the system (but don't run it), use an electronic sniffer to find the leak, recover the R-134a, fix the leak, then recharge with R-12. There is no need to change fittings, flush, convert, unconvert, re-flush, change the blinker fluid, realign the muffler bearings, etc etc etc.

As far as how to flush the system is concerned, it is just a standard A/C system flush procedure like you'd do with any car.

You tear the whole system apart, run an appropriate solvent through the heat exchangers and lines, follow the solvent with shop air to dry the solvent, and reassemble with new drier and expansion valve.

To flush the compressor, you invert it to drain as much oil out as possible, then dribble the new oil into the suction port while you rotate it by hand, then invert and drain, then dribble more in until you've got mostly PAG or whatever new oil you've chosen coming out.

How all the labor to tear it down and flush it is cheaper than a charge of R-12 is beyond me.

Dougflas on Mon July 01, 2013 7:29 PM

>

This is copyrighted material and due to my employer being the Sheriff's Office, I can not do that. I will, however, look up info for you if need be. They do not offer retofitting info; just repair info.

mk378 on Mon July 01, 2013 8:06 PM

What 94RX-7 said.

When confronted with an empty R-12 system-- before taking anything apart (unfortunately it's too late for that now), static pressure test with some other gas and see where you stand as far as what leaks there are.

Edited: Mon July 01, 2013 at 8:07 PM by mk378

Olds442 on Tue July 02, 2013 3:31 AM

If you add it all up its far better to keep it R-12. Works better, it was designed for it and you don't have to re-engineer anything.

Batchman on Sun August 03, 2014 1:30 PM

All right, so in this thread everybody is recommending staying with R12.

So I'm going to ask for some rough estimations.

See, I just got a 1990 Lexus 400 LS. The A/C didn't work, and I assumed there was a major problem with it, but the old owner just told me that, no, the A/C had been working fine, it just needed to be recharged every few years, and since it hadn't been driven much in the last few years, he hadn't bothered to get the recharge.

So if the system is quite possibly fine and only needs a recharge, and the recommendation for this kind of system is to stay with the R12 ... then roughly how much does it usually cost to get an old system like this recharged?

The car is already well-built, and hopefully the engine will last a good many more years, but if I can get the A/C working as well, I will be very happy with this old war horse!

Cussboy on Sun August 03, 2014 1:40 PM

Quote
Originally posted by: Batchman
All right, so in this thread everybody is recommending staying with R12.

So if the system is quite possibly fine and only needs a recharge, and the recommendation for this kind of system is to stay with the R12 ... then roughly how much does it usually cost to get an old system like this recharged?



No - the system is NOT "possibly fine" - it has a leak. I'd estimate $200-$250 for leak detection, repair (if a fitting, bad O-ring, service cap), new drier, evacuation and R12 recharge. If something like the condenser or compressor seal is the source of the leak, then add on for that component.

This is why finding the source of the leak is the first step and so important, because an operational system doesn't leak or use refrigerant.

mk378 on Sun August 03, 2014 3:39 PM

If there is some R-12 left, sniff around with an electronic leak detector and see if you find a leak. On older cars, leaks due to hardening / cracking of the o-rings, especially on the line between the compressor and condenser, are common.

bohica2xo on Thu August 07, 2014 12:13 PM

You mention both Las Vegas & Los Angeles - and a 150 mile one way trip. Safe to say you live in the southwest here someplace.

You have a car with 23+ year old rubber parts, in a place where the air coming IN to the radiator can be over 150f. Yeah, I bet it has a few small leaks. Bear in mind that for the past 23 years while the car has had oil changes, chassis lubrication & fantastic overall care, the same 6 ounces of oil has been circulating in the refrigeration loop. It has never been changed. It has been doing that job for as long as the car has been on the road.

The Lexus has a great system, balanced & calibrated for R12. While I am sure there are some owners in Monterrey or Seattle happy with a 134a conversion, I can tell you form experience that it will not work well in the desert.

You can either rebuild the system to OEM specs & performance - or you can hack away at it, fill it with 134a & tell yourself that the cooling you get is wonderful. Buy lots of cotton clothing, and tell your friends that you like the fresh air with the windows down, like everybody here does with a converted MB. When it is 106 out @ 9am.

The best approach is to carefully leak check the entire system before breaking it down. If it is already apart, you need to start at square one, and build a fresh system:

Flush all of the system that can be flushed to clean & dry, removing all of the oil. See the flushing section here for tips. Handle the EPR carefully,it is not an easy part to replace.

Replace the compressor. New unit. Yes, I know 400 bucks. New clutch, fresh seals everywhere. No worn parts to bite you later.

Replace the Dryer.

Replace any hoses with damage, or any that feel like they are age hardened - here in the desert that can mean most of them. if you bend a hose off of the car in a quiet place & hear any cracking...

Replace EVERY O ring. The site sponsor sells a complete kit of static seals for 10 bucks. Elastomeric parts are where the small leaks usually are.

Once the system is clean & dry inside, add the factory spec volume of oil for the system, evacuate & charge with R12. You have basically a new OEM system. Filled with factory spec fresh oil & refrigerant, ready for another 200,000 miles.

Do it right, do it once. The Site sponsor has the parts,and will ship to anyplace that UPS can find. Sign up for Mitchell On Demand for your Lexus, and make sure your local mechanic reads it.

.

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Edited: Thu August 07, 2014 at 12:15 PM by bohica2xo

Cussboy on Thu August 07, 2014 1:39 PM

Re-read (twice) what Bohica2xo posted above.

And what I posted earlier:

Quote
Originally posted by: Cussboy
Quote
Originally posted by: NickD
D

Agree with iceman, stick with R-12.

Agree also. First of all, why would living in a rural area have anything to do with converting to R134a? Refrigerant is NOT consumed, so R-12 in a leak free system could last for the life of the Lexus. Have the guy add dye and/or use a sniffer and find and fix the leak, and to evacuate and add R-12. If he doesn't have equipment to do R-12 (possible), buy or rent vacuum pump and set of R-12 gauges, and add your own R-12, and you'll have the equipment and still save money and have better performance.

Or let the mechanic use the equipment you buy; most likely his vacuum pump will already have fittings for both R-12 and for R134a, so you won't need to get one. The basic systems are very similar from vehicle to vehicle, and I'll bet he's seen a ton of Toyotas.

If you want to be happy, do the R-12. In that part of the country, an older vehicle can still be rust-free and quite nice, so keep it fully operational with R-12. You've saved a ton of $$$ over the years with it, so use a little and fix it right. The local mechanic's vacuum pump will most likely have connection for R-12 gauge set (most are dual fitting) so you'd only need to get R-12 gauge set and can tap if he's to fill from R-12 cans.

AC_Doc on Thu August 07, 2014 5:46 PM

Quote
As for filling it with 134a finding and fixing the leak, then converting it back to r12. Well that adds a lot of labor. I first have to change fittings, and properly flush, then fix, then change fittings back to r12, and flush again etc... Not a good thing to be doing

"Lots of Labor"???
You just need to put a little liquid R134 (cheaper than R12) into the system so a leak sniffer can locate the leak. No flushing, No oil changing, No service port fitting changing, No running the engine or compressor. Since you must have an R12 manifold set already (or you can borrow one as mentioned earlier) all you need is a single fitting on the R134 can fitting to make it fit the R12 fitting on the yellow hose of the R12 manifold. The fitting is less than $10.

Look up this PN# (Mastercool 82635 - 1/2" ACME F X 1/4" MFL Adapter with gasket) on the web. Fits right on the R134 can or bottle outlet, attach yellow hose end, and charge a small amount of R134 in the system for leak checking. Nothing to it. Its going to leak out anyway.
After the leak is fixed, evacuate the system, put in the compatible oil and charge R12 and you're ready to go.

Worst case: R12 is $20-$30 for a 12 oz. can on Flea-bay. R134 is $14.99 at most any Autoparts store. Difference: $5-$15 per can to stay R12. How many cans do you need to fill the system? How is it cheaper to switch to R134?

AC_DOC



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Sometimes you must accept things at faith value!

Edited: Thu August 07, 2014 at 5:52 PM by AC_Doc