somnoboy

Hello everyone. I'm new to ClubLexus and am very impressed with the very professional expertise exhibited here.

Anyway, I have a 1992 LS 400 with about 92,000 miles. I am the original owner, and have kept the car garaged since birth. It is in mint condition.

Just about a year ago, the air conditioner stopped making cold air. System was converted to R-134 at a Lexus dealership. Since then, a/c worked fine up until yesterday (I think). Now, fan works fine, but with A/C switch on, no cold air is produced. The air being blown is whatever the ambient air is outside. I noticed that when idle in park, that turning the a/c on or off results in absolutely no change in engine rpm. In other words, it almost seems as if the a/c isn't engaging at all. The a/c light stays on steady when selected (no blinking).

I ran an a/c diagnostic code check, and the only codes that show up are 00 and 21 (I was idling in park in the shade, out of direct sunlight).

Any experts out there have any idea? I am very, very proud of my LS 400, and would greatly appreciate anyone's help.

Thanks in advance.

AllblackLS

A question, how much was the r134 conversion? My 90 LS stopped blowing cold air too.

curepunx

iTrader: (3)

Does it only blow warm air?
You know you can get a can of r12 on ebay for about 65+ dollars shipped...

Refill it yourself and be done with it.

tromly

+1, definitely try to refill yourself, the dealership would want 700 for the conversion

damon

Why would he be buying either R-12 or a 2nd conversion to 134A?

Help the guy! What does his code problem translate to, is his system simply low on refrigerant?

shadowless

check lexls

http://www.lexls.com/tutorials/air/accodes.html

also, dont listen to anyone if they say add more refrigerant. that is not how you fix a/c systems. If your low, then its for a reason. read the tutorial stuff then proceed with proper diag. too much refrigerant will cause too high of pressure and can lead to more problems.

somnoboy

$242 all-in. I don't know if that's high or low.

somnoboy

Indeed. Help the guy! I would GREATLY appreciate it. I love my LS400, and plan on keeping/maintaining it until I die.

I checked the Lexls site (in fact, that's where I learned how to do the a/c diagnastic code check), and according to them, code 21 is "Open or short in solar sensor circuit." The webpage also notes that code 21 is possible if running the check in the dark. While I did have the car in the shade, it was otherwise a bright sunny day.

Also, I'm not sure how a solar sensor circuit would cause an a/c not to engage at all. As I mentioned in my original post, turning the a/c on and off while at idle (in Park) results in absolutely no change in engine rpm, and no difference in sound, no hissing out of the vents, etc... Again, it almost seems as if the a/c isn't engaging at all, even though the a/c light comes on when I press the switch.

Is is possible that I have blown an a/c fuse somewhere that causes the a/c system not to turn on at all, even though the a/c indicator light comes on?

Again, thanks in advance to all the experts out here. I love my '92 LS, and would love to keep it forever, but would like to do more maintenance myself, as the local Lexus dealerships seem to be charging truly unreasonable prices for anything more than an oil change.

somnoboy

Thanks for the tip. I had already gone there and learned from that excellent resource how to do the diagnostic check.

The problem is, nowhere on that site does it mention what to do when the a/c doesn't seem to engage at all (no change in engine rpm, no sounds, etc...) even though the a/c light comes on.

Any suggestions from the experts?

TexFinn

I'm no expert in this matter, but it sounds like you could have one of two problems:

1. Electrical problem.
2. No/too little refrigerant in the system. Hence the compressor does not kick on.

I would start with checking all the electrical stuff (fuses, connectors, etc.) between the switch and the compressor to make sure the compressor gets the electricity it needs and then proceed on checking whether there is any refrigerant in the system.

Just my $0.02 worth... Probably not much, but anyway...

Li Ls4

iTrader: (12)

the clutch on the compressor could be worn out. therefore it is not engaging which coudnt cause the car rpms to change.

i have the same problem where i press the ac button and nothing happens even tho the light is on. although i think the major cause of this for me was that my car was involved in a big front end collision which this problem occurred when the car was being rebuilt. so when i got my car the ac was hard wired to a switch which engages the compressor, fans exc.

BUT the down side is that when u r accelerating and the rpms are high the clutch doesnt ease up like it should, thus burning out the clutch

so one alternative is to hard wire it to a switch but the down side is that u would go through ac compressors almost every other season.

somnoboy

Thanks Texfinn. I'm checking out the fuses as I get a few minutes here and there. I already checked the main a/c fuse that the manual calls out: Fuse number 11 located in the interior fuse box under the dash. The manual also notes a circuit breaker under the hood that looks like it provides power to a whole bunch of things. I need to have a look at that when I get a second.

Your suspicion that it may be electronic may be right. A few days ago, it rained very, very heavily around here. I mean Noah's Ark heavy. A lot of localized flooding and driving slow through several inches of water. That may have tripped/shorted something out.

somnoboy

Thanks for responding Li LS4. Would you happen to know how I could positively confirm that the compressor was in fact blown out? Keep in mind, I'm a total neophyte at this mechanical stuff.

By the way, where on Long Island are you located?

Li Ls4

iTrader: (12)

in my case since i can rule out an electrical problem, when u turn the switch on for the ac i hear the fans turn on but still no cold air. i then make sure there is freeon in the car caz i have a very small leak somewhere, and lastly to conform it is in fact the ac compressor i pop the hood and look at the clutch itself while the car is running.

the first time it went, the clutch part that is spun by the belt was wobbeling. i dont remember of any noise.

the second time it went. the same thing happened only there was an addition of like a metal rubing on metal sound which was caused by a broken bearing in the clutch.

i live in bellmore

Amskeptic

Please note that it is all too easy for us keyboard cowboys to throw out our favorite ideas, many of which are only brought up because "it happened to me last week".

You have to get out to your car and start thinking like an engineer.

Start engine. Turn on the A/C. Go look down at the compressor. The pulley will be turning, but we are interested in the center part that sticks out closer to the front of the car. Is it turning? Yes means you have an internal issue to the A/C plumbing/compressor if there is no cold air.

If it is not turning, be brave. Remove the big plastic cover over the fuses and relays. There is a round A/C relay closest to the left fender and it is identified on the diagram inside the cover. Remove it. You will see (if it is factory) two copper spades and two silver spades. You want to bridge the copper spade terminals inside the fuse box with a little piece of wire just to check for the sound of the compressor engaging. You might get a little spark action, no big deal- you at least know you have voltage coming through the load side of the relay, just cram the wire in the terminal slots briefly. This will normally make the idle go up as well.

If this little hot-wire makes the compressor engage, you likely have a low charge of refrigerant. In this case, the relay's control circuit is being told not to engage the relay due to insufficient pressure stopping the electrical circuit to the relay control coil.

If the compressor still does not engage, you have a possible wiring/compressor clutch problem. If you were not a neophyte, I would say check for 12 volts at either of the two terminals on the switch-side of the relay plug. There is a "locked rotor sensor" designed to prevent the clutch from killing itself if the compressor is seized up. This will cause a blink in the little green light at the switch.
Colin