91 Ls400 Ac Out

[MISTER_I_US]

I went to get my Car serviced for Oil and had them check the fluids in my car and they checked the battery... then after that my AC was blowing out air and wouldnt blow cool air... ive checked the wires wich were fine and the antifreeze level.. and everything was fine.. do any of you have any suggestions.. I would like to fix it myself.. and im thinking it my be the fuses or the Circuit breaker.. I live in New Mexico were im pretty far from a dealer...

[VBdenny]

My 90 does that same thing. It worked great, then the compressor stopped turning, the clutch isn't engaging. I took it to a dealer and they said the compressor was "locking up". I know there is usually an automatic circuit breaker to prevent damage when the charge is low but I'm not sure on the Lexus. I suspect there is some type of lockout for the compressor. I was under the car yesterday looking at how to get at the compressor to change it when I was doing an oil change. Man, it is kind of buried up there behind the oil filter.

Before I change the compressor and dryer, I would really like to know if I really need a new compressor, or if it could be the clutch engage. I think I'm going to have it checked out at another place for a second opinion. I know the dealer can fix it, it's just that I know they will say I need everything and charge a couple of thousand.

I will state one thing I DO know. Driving a LS400 in the summer without A/C is torture!

[Rich Sweitzer]

Yes to both items on the LS-400.

There is a combination low pressure and high pressure lock out switch behind the passenger side headlamp (near the AC system's receiver/dryer). One set of contacts opens if the pressure is to low so that the compressor can't run. The other set of contacts independently starts the electric fans in front of the radiator if the pressure goes too high.

The ECU for the AC system constantly monitors the rotation of the compressor when it is running and compares it with the engine speed. If it appears to the ECU that the compressor is running slower than it should it assumes an imminent compressor lockup and will disengage the compressor clutch to prevent catastropic system damage. (Having experienced the "black death" on another vehicle, I very much appreciate that feature.)

I believe that the AC system ECU will tell you what's going on by giving an error code or codes (assuming that you have one of the very rare ECUs that hasn't experienced display failure). To put the unit into diagnostic mode you need to hold in two of the buttons (AUTO and REC (Recirculate)) while turning on the ignition switch. The temp display should then flash one or more two digit codes that "tell the story". (I have the shop manual, but not handy; so if codes show post here or e-mail and I'll let you know what they mean.)

The other thing that you could do is measure the gas pressure. Most auto parts stores have a cheap and dirty AC pressure gauge (looks like a tire gauge) that will tell you if the pressure is below the "ON" point for the above mentioned safety switch. (Less than 10-15 psi for a no-go, could be as high as 70-80 psi for a properly charged system sitting on a hot day). The suction line service port is in the engine compartment very near the firewall on the passenger side of the vehicle. High side port is just (as facing the car from the front) to the left side of the radiator, tucked in behind the pasenger side headlamp assembly. (Please be careful to not discharge any more refridgerant than is absolutely necessary while doing this test, regardless of the type in the system.)

The AC system on my '91 LS-400 didn't work at the beginning of this summer; the compressor not running being the prime symptom. Turned out that the manifold gasket on the compressor had failed. Replaced the $10 gasket, evacuated and then recharged the system, and all was well.

Good luck

[VBdenny]

Thanks Rich,

Excellent information. Sometimes it's difficult to start, without a starting point. I'll check this stuff out this week and let you know if I get any codes.

Denny

[ToddLS400]

Thanks for the info Rich. I didn't know how to check codes. Mine blinks "temp 00". I believe everything is fine? That's a cool way to check codes without having to hookup to an external computer. Does the check engine light come on when there is a code present?

If you wait about a minute or os as it blinks "00", it will go through the fan speed range starting at the # 20 up to 30 as the fan speed automatically adjusts higher from low to high. Then it repeats. Why does it do that I wonder? What do the #'s mean (20-30)?

[SKperformance]

Thanks for the info Rich. I didn't know how to check codes. Mine blinks "temp 00". I believe everything is fine? That's a cool way to check codes without having to hookup to an external computer. Does the check engine light come on when there is a code present?

If you wait about a minute or os as it blinks "00", it will go through the fan speed range starting at the # 20 up to 30 as the fan speed automatically adjusts higher from low to high. Then it repeats. Why does it do that I wonder? What do the #'s mean (20-30)?

the system does a cuircit check

by testing all of the servo motors for the fans and actuators that control air flow and temp which is what the numbers are

it is just the check particular to that #

i think 00

is ok

do a search and it is already posted in the sc forums

i am not a mod in this section or i would mergwe the 2 topics so you could see the codes and what they mean

another thought is

does the ac light blink

if it does then it means the compressor is sensing lock up and has stopped

did the shop do a fluid top up of refrigerant

if they used the wrong one you are infor lots of fun

also there are a few wires that are part of the a/c compressor

trace back the wiring and look to see if any have been damaged

if so it may cause th wire to ground thinking that the system is locking up and shut down

good luck

[MISTER_I_US]

88 and 33 thanks for the help let me know what it means...

[VMF]

i wish i could help, but i dont even have those codes for my LS in the book:) prolly they changed a lot in the heating/cooling system for gen 2

[ToddLS400]

88 and 33 thanks for the help let me know what it means...

I have the shop/repair manual for the '91 LS400. Here's what I've found.

code 33 = 1> Open in air mix damper position sensor circiut 2> Open or short in air mix servometer circuit 3> Air mix servometer locked.

I can't find 88 yet, but I'll look...

BTW, to check your AC system codes: Hold "AUTO" (not "OFF") and the "REC" switch when turning the ignition switch on.

[MISTER_I_US]

thanks for that info... Im not sure what that means but hopefully Rich or someone knows what that means and how to fix it..

[obergc]

-Do you have a blinking A/C light on the climate control panel? If so your compressor is locked up. There is a sensor on the back of the compressor that senses when the compressor isn't turning when it should be. There is a connector for the sensor on the back of the compressor. It is located right above the oil filter. If they changed the filter, maybe they messed with the wiring while they were in there. The compressor actually is pretty easy to replace, it comes out from the top, remove the battery and battery tray first and you have plenty of room. Good place to get a replacement rebuilt compresor is Pace Compressor in Tampa Florida. Replacement is $200 plus shipping, at least that's what I paid for mine.

Curt

[MISTER_I_US]

When is the AC light suppose to blink.. before or after I do the code check?

[SKperformance]

the ac light blinks when ever the car is turned on and the a/c is turned on

as it is sayig the sensor is sensing lock up in the compressor

[MISTER_I_US]

No it doesnt do that I checked this morning

[spiller91ls]

Try turning on you a/c, open the hood and look to see if your compressor is turning. this should clear tell you if you don't have enough freon in the system. where in NM do you live, I live in Silver City and have a 91 ls. I also have the shop manuels for the car.

[MISTER_I_US]

I will check that out.. but Im not sure thats the reason... even though the freon is a somewhat below the low mark... My trac light is on so it has to be more than just the freon... but it might be that... and I live in Alamogordo New Mexico... I just want to know what I need to check for code 33 cuz I dont know where the servometer circuit is or the sensor circuit is located so I can check it....

[VBdenny]

Since my A/C stopped working, I did the AUTO REC and came up with codes 21 and 33. I saw the 33 was something about a sensometer. I would be interested to find out what 21 means since I didn't see anyone else that had that one posted.

[spiller91ls]

I'll try and see what a code 33 is in the books, but i wont be able to get back to you untill tomarrow. I will be in alamo on 8/24, i'll be shooting at the ipsc match at La Luz, maybe if your still having the problem I can help you then.

John aka spiller

[VBdenny]

My A/C compressor doen't turn and the light doesn't blink, just steady green. I checked the codes and got 21 and 33. I really appreciate the advise on removing the battery and tray to get at it. Now that I went and looked at it I see what you mean. Do the compressors come with oil, or do you have to add it? I'll assume the come evacuated. Luckily, I have 30lbs. of R-12 which I bought at Costco for $79 (in about 1990). so I won't need to retrofit for R-134a or anything. Any other tips would be helpful. Do you have a number for Pace?

[spiller91ls]

a code 21 is a solar sensor alarm. what happend is you probably got the codes when it was dark or you did it in a garage. what you need to do is check the codes in the sun or place a light above the passenger windsheild, the sensor is on the passenger side of the defroster, it's the little bump at the end of the vent. just get some light on it when you check the codes, and it should go away

[MISTER_I_US]

Diu anyone find what Temp 88 means... Im still stuck on that one.. and I dont have a book

[VBdenny]

Thanks Spiller, uh yeah, I did check it in the garage. I'll try it outside, I still have the 33 which someone said is a sensomatic. Lexus dealer blamed it on a compressor lockup, but I never heard noise or had the a/c light blink. Think they were wrong?

Denny

[VBdenny]

88 and 33 thanks for the help let me know what it means...

I have the shop/repair manual for the '91 LS400. Here's what I've found.

code 33 = 1> Open in air mix damper position sensor circiut 2> Open or short in air mix servometer circuit 3> Air mix servometer locked.

Hey Todd, do you happen to have any information on what or where the air mix servometer is?

I'd kinda like to be forwarned before I get into this thing.

Thanks

Denny

[sebastor]

-Do you have a blinking A/C light on the climate control panel?  If so your compressor is locked up.  There is a sensor on the back of the compressor that senses when the compressor isn't turning when it should be.  There is a connector for the sensor on the back of the compressor.  It is located right above the oil filter.  If they changed the filter, maybe they messed with the wiring while they were in there.  The compressor actually is pretty easy to replace, it comes out from the top, remove the battery and battery tray first and you have plenty of room.  Good place to get a replacement rebuilt compresor is Pace Compressor in Tampa Florida.  Replacement is $200 plus shipping, at least that's what I paid for mine.

Curt

OK. On mine that is exacly what is happening.

First i noticed that compressor was making loud noices when i turned on a/c however i noticed it was blowing worm air. So i though it's probably dry on oil and a/c. I bought can of a/c with oil already in can.

Charged it and then compressor made noise for 30 min then it stop and blinkin light started to blink..

1. Must i replace compressor or what ?

2. Is there metal debris inside the system ?

3. If yes do i need this filter http://www.auto-air-compressor.com/filter.htm or is there sensor protection not to allow debris to get into the system ?

4. Can i find it cheaper then $299 ?

[UCF3]

I'm guessing, but if the system in locked up, there is metal debris in the compressor.

As for the compressor price, i might be able to get it a little cheaper, but I won't be able to find out until Monday. Private Message me this weekend if you're interested.