Air Conditioning

[hp1480]

I own a 92 LS400 .In 2002 I replaced the whole airconditioning (compressor,clutch,evaprorator etc)went from R12 to R134a fluid.Now my compressor is failing again ,and I talked to this highly regarded mechanic about replacing the compressor with an aftermarket unit.He said that he could do that but would only do it if I agreed to go back to R12 fluid.He claimed that the replacement unit that was able to use R134 was shortening the life of the unit ,even though it would work with R134 ,I would be better off going back to R12.Is he correct in that ,or is he misinformed .

[sonyman]

Your mechanic is a moron.

[wwest]

Your mechanic is a moron.

Agreed, seconded.

[larryp]

Your mechanic is a moron.

Agreed, seconded.

I'll 3rd that. I think you need to drop the "highly regarded" from his title. Compressors are designed to run on R134a. When a conversion is done it's important to get all of the r12 out of the system since the 2 refrigerants are not compatible. Also important to use the right kind and amount of compressor oil. I also replaced all the o-rings when i did mine. May have been overkill but many recommend it. I suspect that there was something missed on your original conversion to R134. Check out Tech Choice Parts, or AC Parts Now. I bought AC parts from both places and was happy with prices and service. Then find another reputable mechanic.

[wwest]

Your mechanic is a moron.

Agreed, seconded.

I'll 3rd that. I think you need to drop the "highly regarded" from his title. Compressors are designed to run on R134a. When a conversion is done it's important to get all of the r12 out of the system since the 2 refrigerants are not compatible. Also important to use the right kind and amount of compressor oil. I also replaced all the o-rings when i did mine. May have been overkill but many recommend it. I suspect that there was something missed on your original conversion to R134. Check out Tech Choice Parts, or AC Parts Now. I bought AC parts from both places and was happy with prices and service. Then find another reputable mechanic.

"..the 2 refrigerants are not compatible."

In what way.

I know that this is common knowledge, commonly accepted knowledge, but I have never seen any evidence or proof of same.

My A/C specialist says that the only reason to pump down the system of R12 is to remove the potential for any residual R12/22, freon, from simply being dumped into the atmosphere during future work since that's what's allowed with INEXPENSIVE R134a.

[wwest]

I own a 92 LS400 .In 2002 I replaced the whole airconditioning (compressor,clutch,evaprorator etc)went from R12 to R134a fluid.Now my compressor is failing again ,and I talked to this highly regarded mechanic about replacing the compressor with an aftermarket unit.He said that he could do that but would only do it if I agreed to go back to R12 fluid.He claimed that the replacement unit that was able to use R134 was shortening the life of the unit ,even though it would work with R134 ,I would be better off going back to R12.Is he correct in that ,or is he misinformed .

There is an unusual design aspect of the '92 LS400's A/C system that even your (even were it true) "highly regarded" mechanic might be unaware.

It has an EPR valve upstream of the evaporator core. These are more commonly used to "meter" the high side liquid refrigerant when two or more separate evaporators are used on one compressor/condensor system. Without the EPR one evaporator could potentially HOG all of the cooling capacity. Front/rear A/C setups in minivans for instance. I have come to believe that Lexus used the EPR to lessen the noise factor "HISS" that you might otherwise get with 200 psi pressure differential between the liquid and gas side, across the input and output of the expansion valve.

The Lexus EPR valve, even during "normal" operation can/will often allow refrigerant cooling capacity to exist beyond the evaporator core, and into the refrigerant return lines to the suction side of the evaporator. After a long period of operation on a humid day I often see 1/4 of rime ice accummulated on these return lines.

So, should the EPR valve be maladusted (it has a "back-pressure" adjustment) or fail in a way that causes liquid refrigerant to reach the compressor inlet, the compressor life will be shortened substantially, due to something called compressor "slugging".

[larryp]

"..the 2 refrigerants are not compatible."

In what way.

I know that this is common knowledge, commonly accepted knowledge, but I have never seen any evidence or proof of same.

My A/C specialist says that the only reason to pump down the system of R12 is to remove the potential for any residual R12/22, freon, from simply being dumped into the atmosphere during future work since that's what's allowed with INEXPENSIVE R134a.

I'm no chemist but even the replacement compressor i got was stamped with R134 only. They obviously have different chemical makeups so one would assume all of the warnings about mixing the 2 have some merit - but i can't attest to it personally. If they are compatible then i wasted a bunch of time and effort swapping out the o-rings :cries:

[hp1480]

Your mechanic is a moron.

Agreed, seconded.

I'll 3rd that. I think you need to drop the "highly regarded" from his title. Compressors are designed to run on R134a. When a conversion is done it's important to get all of the r12 out of the system since the 2 refrigerants are not compatible. Also important to use the right kind and amount of compressor oil. I also replaced all the o-rings when i did mine. May have been overkill but many recommend it. I suspect that there was something missed on your original conversion to R134. Check out Tech Choice Parts, or AC Parts Now. I bought AC parts from both places and was happy with prices and service. Then find another reputable mechanic.

[hp1480]

I thank you for your good advise .It didnt seem logical although the compressor that is failing was a retrofitted one so I could use 134a instead of R12.

[hp1480]

I own a 92 LS400 .In 2002 I replaced the whole airconditioning (compressor,clutch,evaprorator etc)went from R12 to R134a fluid.Now my compressor is failing again ,and I talked to this highly regarded mechanic about replacing the compressor with an aftermarket unit.He said that he could do that but would only do it if I agreed to go back to R12 fluid.He claimed that the replacement unit that was able to use R134 was shortening the life of the unit ,even though it would work with R134 ,I would be better off going back to R12.Is he correct in that ,or is he misinformed .

There is an unusual design aspect of the '92 LS400's A/C system that even your (even were it true) "highly regarded" mechanic might be unaware.

It has an EPR valve upstream of the evaporator core. These are more commonly used to "meter" the high side liquid refrigerant when two or more separate evaporators are used on one compressor/condensor system. Without the EPR one evaporator could potentially HOG all of the cooling capacity. Front/rear A/C setups in minivans for instance. I have come to believe that Lexus used the EPR to lessen the noise factor "HISS" that you might otherwise get with 200 psi pressure differential between the liquid and gas side, across the input and output of the expansion valve.

The Lexus EPR valve, even during "normal" operation can/will often allow refrigerant cooling capacity to exist beyond the evaporator core, and into the refrigerant return lines to the suction side of the evaporator. After a long period of operation on a humid day I often see 1/4 of rime ice accummulated on these return lines.

So, should the EPR valve be maladusted (it has a "back-pressure" adjustment) or fail in a way that causes liquid refrigerant to reach the compressor inlet, the compressor life will be shortened substantially, due to something called compressor "slugging".

[hp1480]

Thats very interesting ,this is what happened .My compressor& clutch failed after 8 years and 105832 miles.I was in Montreal at the time and had Lexus replace compressor with a new one .In May 2002 after 15832 miles the compressor was dying and so was the evaporator .I replaced the compressor with a remanufactered Lexus part (Lexus gave me the replacement at no charge )and the evaporator,an expansion valve was also put in ,the O rings were replaced and receiver assembly .Now 5 years later and after 33498 miles ,I'm faced with needing another compressor & clutch .The one thing that may bear out this so called moron mechanic is ,on freon the AC lasted 105000 miles .On 134a 15000 & 33000 miles.

[The Big Bow Wow]

the compressor doesnt care what refrigerant you use, just the oil. you cannot mix refrigerants its like oil and water, also you must vacuum the system, its illegal to dump any large amount refrigerant into the atmosphere! my truck has 250K miles on the stock compressor with 134A, you need to find a mechanic that knows how to properly convert a system

[JPI]

I own a 92 LS400 .In 2002 I replaced the whole airconditioning (compressor,clutch,evaprorator etc)went from R12 to R134a fluid.Now my compressor is failing again ,and I talked to this highly regarded mechanic about replacing the compressor with an aftermarket unit.He said that he could do that but would only do it if I agreed to go back to R12 fluid.He claimed that the replacement unit that was able to use R134 was shortening the life of the unit ,even though it would work with R134 ,I would be better off going back to R12.Is he correct in that ,or is he misinformed .

Hi there,

I've successful convert many R-12 system to R-134 with no problem. Many folks giving it a bad rep because they wouldn't take the time to do it right or lack of knowledge how the a/c works. This vehicle actually designed for R12 so it will work much better with R-12 but where can we find R-12? The gray market? We have seen 104 degree here in the Dallas, TX area the past week. I've convert a couple of them last week, air blows 28 degree out of the vents in 104 degree temp. Here are some tips:

- Flush the system

- Replace all the 0-rings and lube them up with oil

- Use the right oil for your a/c system

- Replace the drier once the system is open up

- Recharge the proper amount of oil

- Recharge the proper of R-134(usually 10-15 less than your R-12 system)

- Last but not least converting the system isn't cheap. Bring it to someone has the knowledge. Pay for the reapair Once not Twice!!!

JP Importz

[wwest]

I own a 92 LS400 .In 2002 I replaced the whole airconditioning (compressor,clutch,evaprorator etc)went from R12 to R134a fluid.Now my compressor is failing again ,and I talked to this highly regarded mechanic about replacing the compressor with an aftermarket unit.He said that he could do that but would only do it if I agreed to go back to R12 fluid.He claimed that the replacement unit that was able to use R134 was shortening the life of the unit ,even though it would work with R134 ,I would be better off going back to R12.Is he correct in that ,or is he misinformed .

Hi there,

I've successful convert many R-12 system to R-134 with no problem. Many folks giving it a bad rep because they wouldn't take the time to do it right or lack of knowledge how the a/c works. This vehicle actually designed for R12 so it will work much better with R-12 but where can we find R-12? The gray market? We have seen 104 degree here in the Dallas, TX area the past week. I've convert a couple of them last week, air blows 28 degree out of the vents in 104 degree temp. Here are some tips:

- Flush the system

Flush the system, actually..?? Or do you really mean pump it down to a HARD vacuum..?

- Replace all the 0-rings and lube them up with oil

Why...?? My seals have worked for 150,000 miles... And with what oil...??

- Use the right oil for your a/c system

Wouldn't the "right" oil for the system mean being compatible with the original R-12..??

- Replace the drier once the system is open up

First pump it down to a HARD vacuum, undoubtedly removing ALL the H2O, and NOW remove the drier..? Why?

- Recharge the proper amount of oil

Doesn't the commercially packaged for retail R-134 come with the oil mixed in...??

- Recharge the proper of R-134(usually 10-15 less than your R-12 system)

Or simply recharge to the level that results in the proper low side pressure, ~40 lbs, as directed in the DIY kit..!

- Last but not least converting the system isn't cheap. Bring it to someone has the knowledge. Pay for the reapair Once not Twice!!!

$50 for the DIY kit including 32 oz of R-134, ~$100 for a reputable A/C specialty shop to do it. Key words = REPUTABLE & A/C SPECIALTY SHOP...!

JP Importz

[Kennyr]

I converted my 91 over to R134 3 or 4 years ago without replacing anything but the refrigerant and oil and have not had any leaks or problems since. My a/c works great, good enough to keep me cool even in long sleeve dress clothes on 100 degree days with the R134 in place. I have had a couple o-ring issues before the conversion though. I've converted many cars over this way over the years, other makes, and no comebacks. I still work on these cars and I would know if they were leaking. Change all o-rings and receiver dryer. Not needed. Can't hurt but a waste of time and money.

[JPI]

I own a 92 LS400 .In 2002 I replaced the whole airconditioning (compressor,clutch,evaprorator etc)went from R12 to R134a fluid.Now my compressor is failing again ,and I talked to this highly regarded mechanic about replacing the compressor with an aftermarket unit.He said that he could do that but would only do it if I agreed to go back to R12 fluid.He claimed that the replacement unit that was able to use R134 was shortening the life of the unit ,even though it would work with R134 ,I would be better off going back to R12.Is he correct in that ,or is he misinformed .

Hi there,

I've successful convert many R-12 system to R-134 with no problem. Many folks giving it a bad rep because they wouldn't take the time to do it right or lack of knowledge how the a/c works. This vehicle actually designed for R12 so it will work much better with R-12 but where can we find R-12? The gray market? We have seen 104 degree here in the Dallas, TX area the past week. I've convert a couple of them last week, air blows 28 degree out of the vents in 104 degree temp. Here are some tips:

- Flush the system

Flush the system, actually..?? Or do you really mean pump it down to a HARD vacuum..?They sell the flushing chemical at any a/c supply outlet. What do you mean why pump it down to a HARD VACCUM? Is this how you flush the system?

- Replace all the 0-rings and lube them up with oil

Why...?? My seals have worked for 150,000 miles... And with what oil...??Once you open up the lines, It's wise to replace the 0-rings. We had a quite a few 0-rings after the convertion.

- Use the right oil for your a/c system

Wouldn't the "right" oil for the system mean being compatible with the original R-12..?? Would be surprise what kind of oil people will put in the a/c system.

- Replace the drier once the system is open up

First pump it down to a HARD vacuum, undoubtedly removing ALL the H2O, and NOW remove the drier..? Why? Since you asked me this question, I don't think you ever work on an a/c system before

- Recharge the proper amount of oil

Doesn't the commercially packaged for retail R-134 come with the oil mixed in...??Nope

- Recharge the proper of R-134(usually 10-15 less than your R-12 system)

Or simply recharge to the level that results in the proper low side pressure, ~40 lbs, as directed in the DIY kit..!

- Last but not least converting the system isn't cheap. Bring it to someone has the knowledge. Pay for the reapair Once not Twice!!!

$50 for the DIY kit including 32 oz of R-134, ~$100 for a reputable A/C specialty shop to do it. Key words = REPUTABLE & A/C SPECIALTY SHOP...!

JP Importz

[wwest]

I own a 92 LS400 .In 2002 I replaced the whole airconditioning (compressor,clutch,evaprorator etc)went from R12 to R134a fluid.Now my compressor is failing again ,and I talked to this highly regarded mechanic about replacing the compressor with an aftermarket unit.He said that he could do that but would only do it if I agreed to go back to R12 fluid.He claimed that the replacement unit that was able to use R134 was shortening the life of the unit ,even though it would work with R134 ,I would be better off going back to R12.Is he correct in that ,or is he misinformed .

Hi there,

I've successful convert many R-12 system to R-134 with no problem. Many folks giving it a bad rep because they wouldn't take the time to do it right or lack of knowledge how the a/c works. This vehicle actually designed for R12 so it will work much better with R-12 but where can we find R-12? The gray market? We have seen 104 degree here in the Dallas, TX area the past week. I've convert a couple of them last week, air blows 28 degree out of the vents in 104 degree temp. Here are some tips:

- Flush the system

Flush the system, actually..?? Or do you really mean pump it down to a HARD vacuum..?They sell the flushing chemical at any a/c supply outlet. What do you mean why pump it down to a HARD VACCUM? Is this how you flush the system?

I do not doubt that a flushing "chemical" can be purchased, but assuming this is a conversion, not a repair, is it really normal to do a flush?

- Replace all the 0-rings and lube them up with oil

Why...?? My seals have worked for 150,000 miles... And with what oil...??Once you open up the lines, It's wise to replace the 0-rings. We had a quite a few 0-rings after the convertion.

"Once you open up the lines.."

Why would you do anything other, more, than tap into the shrader valves? Again "this" is a simple conversion, not a repair.

- Use the right oil for your a/c system

Wouldn't the "right" oil for the system mean being compatible with the original R-12..?? Would be surprise what kind of oil people will put in the a/c system.

- Replace the drier once the system is open up

First pump it down to a HARD vacuum, undoubtedly removing ALL the H2O, and NOW remove the drier..? Why? Since you asked me this question, I don't think you ever work on an a/c system before

Well, first, I'm pretty good at comprehending and understanding what I read, so I'm pretty sure I understand how the drier works and why. Second, I have had a good A/C specialty shop owner/technician tell me that once the system is fully pumped down the drier is restored to "like new" capability.

- Recharge the proper amount of oil

Doesn't the commercially packaged for retail R-134 come with the oil mixed in...??Nope

Are you certain sure of this, ALL brands?

- Recharge the proper of R-134(usually 10-15 less than your R-12 system)

Or simply recharge to the level that results in the proper low side pressure, ~40 lbs, as directed in the DIY kit..!

- Last but not least converting the system isn't cheap. Bring it to someone has the knowledge. Pay for the reapair Once not Twice!!!

$50 for the DIY kit including 32 oz of R-134, ~$100 for a reputable A/C specialty shop to do it. Key words = REPUTABLE & A/C SPECIALTY SHOP...!

JP Importz

[Bthiel]

My compressor& clutch failed after 8 years and 105832 miles.I was in Montreal at the time and had Lexus replace compressor with a new one .In May 2002 after 15832 miles the compressor was dying and so was the evaporator .I replaced the compressor with a remanufactered Lexus part (Lexus gave me the replacement at no charge )and the evaporator,an expansion valve was also put in ,the O rings were replaced and receiver assembly .Now 5 years later and after 33498 miles ,I'm faced with needing another compressor & clutch.

You are having the same experience with 134 that we had with R12. The first time Lexus covered it. The second time Lexus didn't cover it. The third time he took it in the repair was not going to be covered. My dad bought all the equipment to do the job himself, got a license (or certification, or whatever it is) to buy R12 and spent weeks researching the issue. A car with (at the time of the last failure) less than 65,000 miles on it should not be on its fourth a/c compressor. I'm almost certain the problem was the "slugging" referred to in a prior post caused by not adjusting the valve (he replaced his and adjusted it - I know because he replaced *everything* and adjusted it), but I do know with a high degree of confidence that this was caused by some $100 thing the dealership was not-doing when they charged $1,200 or $1,400 to "almost-do" the repair.

A letter was written to Lexus concerning this and the fact that a Lexus dealer's repair was lasting no-time. It was pointed-out to them that a car that needs a new a/c compressor every 8,000-15,000 miles is evidence that something is wrong. Lexus' response was essentially, "Gee, we're sorry about that," followed by a blurb about the standard warranty on repairs. In other words, nobody really read the letter, or they didn't care, or something. I'd have been in small-claims court.

The compressor would whine and complain before dying. When he took it to the dealership he was told, "Yeah, a lot of them do that. Get ready to buy a new compressor. Nothing we can do." Amazing. Simply amazing.

WHY do you need to take photocopies of the manuals with you and FORCE the mechanic to initial every step of a clearly defined procedure? Especially at Lexus' labor rates, you would *think* that something like that was being done and that you could count-on Lexus to perform the work correctly. It has been my unfortunate experience that *seldom* does my car go-in for expensive service that gets done correctly the first time. There's usually a return trip and it's usually because somebody didn't follow the procedure in the manual. This was true of two '91 ES250s (I've got a story about one of those ES250s involving a visit from some Japanese fellows I'll tell sometime - I raised hell, and Lexus responded), and now the '92 LS is following suit. I don't think it has been successfully repaired the first time, ever (two different dealerships). I have somewhat better luck with the 2002 ES.

B

[wwest]

My compressor& clutch failed after 8 years and 105832 miles.I was in Montreal at the time and had Lexus replace compressor with a new one .In May 2002 after 15832 miles the compressor was dying and so was the evaporator .I replaced the compressor with a remanufactered Lexus part (Lexus gave me the replacement at no charge )and the evaporator,an expansion valve was also put in ,the O rings were replaced and receiver assembly .Now 5 years later and after 33498 miles ,I'm faced with needing another compressor & clutch.

You are having the same experience with 134 that we had with R12. The first time Lexus covered it. The second time Lexus didn't cover it. The third time he took it in the repair was not going to be covered. My dad bought all the equipment to do the job himself, got a license (or certification, or whatever it is) to buy R12 and spent weeks researching the issue. A car with (at the time of the last failure) less than 65,000 miles on it should not be on its fourth a/c compressor. I'm almost certain the problem was the "slugging" referred to in a prior post caused by not adjusting the valve (he replaced his and adjusted it - I know because he replaced *everything* and adjusted it), but I do know with a high degree of confidence that this was caused by some $100 thing the dealership was not-doing when they charged $1,200 or $1,400 to "almost-do" the repair.

A letter was written to Lexus concerning this and the fact that a Lexus dealer's repair was lasting no-time. It was pointed-out to them that a car that needs a new a/c compressor every 8,000-15,000 miles is evidence that something is wrong. Lexus' response was essentially, "Gee, we're sorry about that," followed by a blurb about the standard warranty on repairs. In other words, nobody really read the letter, or they didn't care, or something. I'd have been in small-claims court.

The compressor would whine and complain before dying. When he took it to the dealership he was told, "Yeah, a lot of them do that. Get ready to buy a new compressor. Nothing we can do." Amazing. Simply amazing.

WHY do you need to take photocopies of the manuals with you and FORCE the mechanic to initial every step of a clearly defined procedure? Especially at Lexus' labor rates, you would *think* that something like that was being done and that you could count-on Lexus to perform the work correctly. It has been my unfortunate experience that *seldom* does my car go-in for expensive service that gets done correctly the first time. There's usually a return trip and it's usually because somebody didn't follow the procedure in the manual. This was true of two '91 ES250s (I've got a story about one of those ES250s involving a visit from some Japanese fellows I'll tell sometime - I raised hell, and Lexus responded), and now the '92 LS is following suit. I don't think it has been successfully repaired the first time, ever (two different dealerships). I have somewhat better luck with the 2002 ES.

B

I don't know, cannot tell you, about other LS400 MY's than '92, but there is a unique aspect of the '92 that will/can make them especially subject to compressor slugging. The '92 LS400 uses an EPR, Evaporator Pressure Regulator, valve downstream of the evaporator. I think I was told at one time that this was used to "quiet" the refrigerant evaporative process as it enters the evaporator core via the expansion valve. If I understand the operation of the EPR valve correctly its purpose is to not allow the full vacuum "pressure" of the suction side to be "felt" within the evaporator. Bacically it regulates the level of metering of the flow into the evaporator chambers by providing a back-pressure to that flow.

I have often seen the inlet lines to the compressor covered with rhime ice up to a level of 1/4". That would be a clear indication that the refrigerant's evaporative process is continuing beyond the EPR and possibly all the way to the compressor inlet.

It seems very probable to me that with refrigerant cooling capacity existing so obviously existing downstream of the EPR itself there would be an extremely high likelihood of the EPR valve freezing into position, shut, or almost shut. In that case liquid refrigerant would undoubtedly reach the compressor.

While I'm here there is yet another anomally of the '92 A/C system.

About the second summer, 93, we owned the '92 we made a trip to MT. On the return as we were climbing the pass West of Helena the system airflow turned quite warm. I fiddled with the controls a bit to no avail and then as we neared the top of the pass I pulled into a pull-out to check things over. Nothing seemed amiss under the hood or otherwise so I pulled out to continue on our way and immediately realized that the A/C was again operating properly.

I think I reported this to Lexus of Bellevue and got a shrug of shoulders.

About 5 years ago now I happened to be driving another '92 LS400 on I5 in northern CA, again, in the sumemr, headed home to Seattle. As we were climbing one of the Passes on I5 nearing the OR border the same thing happened. Pull over, stop, raise the hood, look things over, get back in and drive away and the A/C is again working just fine.

????....

A little background that may or may not matter.

Some years ago now I owned a Ford Pinto Station wagon, I4 engine. My drive home wasa bout 25 miles, Bellevue to Federal Way. Almost like clockwork about 5 miles after I left work the Pinto engine would start stumbling, studdering and then die. It would restart, stumble, !Removed!, and then die. I could get out, open the hood, look things over, get back in and start the engine and drive away.

What..WHAT...?

I eventually discovered that the vacuum motor that moved the damper forcing the intake airflow over the exhaust manifold had failed. Apparently, starting out with the engine cold (remember that that I4 did not generate a lot of heat anyway) it would take about 5 miles for the fuel's evaporative process in the throat, venturi, of the carburator to freeze it shut. My carborator was icing up since there was no carborator HEAT. Shut the engine down, no more evaporative cooling, the ice melts and now the engine runs fine.

See the parallel...??

But why, how, would elevation have such an effect on the LS400's A/C system? I assume the EPR was freezing shut but why only at higher altitudes?