I have a 2004 LS430 with 74,00 miles and am the original owner. For the past 3 years I have been experiencing infrequent times when nothing but warm or hot air blows from the vents. I would guess that the air works OK at least 95% of the time, but it is very inconvenient when it doesn't work.

Everything on the air conditioning panel on the dash (I don't have nav) looks normal and the few times I have been unable to check under the hood it looks like the compressor clutch is running.

When it happens, it is always when I start up the car and sometimes after a few minutes the air start working, other times it continues to blow warm air until I turn off the air and turn it back on or turn off the car and restart again. It also doesn't seem to be dependent on weather conditions and happens randomly.

I was able to get the car to the dealer while the air wasn't working and left it running while they checked it. The dealer said they found no codes and determined the compressor needs replacing. Including the evacuating and recharging the system they want $1200 for a genuine Lexus compressor.

I was wondering if anyone has experienced this condition with the air and if so was the compressor?

It just seems to me that the compressor either would work all the time or not at all. So before I lay out the $1,200 I thought I'd ask here.

 

The compressor is very reliable. While it could be an intermittent failure, I think it is quite unlikely.
The next time it blows hot air, do two things:
1. Take a peek at the light glass & look it up on the web to interpret what you see.
2. Enter it as a candidate in the next congressional election.
You may also check the voltage to the magnetic clutch to see if the problem is there.

 

Love #2!

 

If the clutch is engaging, and you are still not getting cold air, I would think maybe a clog in the orifice tube. If the clutch is not engaging when this condition occurs you might be just borderline on the amount of Freon charge it takes to kick the compressor clutch on. These systems are designed to stop kicking on the clutch if your charge dips below a certain point, because low charge means you are low on oil. Take it to an autoparts store than can hook up some ac gauges to it. If you have a plugged orifice tube you will have very high pressure on the high side of the system, and unusually low pressure on the low side of the system. With the car off, the low side pressure should just about equal the degrees in Fahrenheit. If the low side is below this amount, this would indicate a low charge.

 

Yes it is likely the compressor is failing, based on my experience. I had the exact same problem, very annoying for a couple years. Turns out the compressor was locking up intermittently. I had made sure the refrigerant was at the proper level, which helped, but the problem would still occur. Even replaced the high pressure switch. Finally replaced the compressor as advised by a local tech and problem is solved. I got a new Denso compressor off ebay for $325.

 

These cars really aren't that expensive as the internet and e bay and salvage yards open up options.

 

Make sure the dealer will stand behind the diagnostics if you replace the compressor. I haven't read very much about a/c problems with the LS430.

 

I wouldn't go the dealer route, and to me it honestly sounds like they're just "shotgunning" parts at it with the most expensive option they have, a new compressor.

It could be an older serpentine belt that's slipping. Or does the ac clutch rapidly "click" at all? That can indicate a low charge and maybe it's just low enough to work intermittenly? I noticed your car has really low mileage, when cars go long periods of time without using the AC, leaks can develop from the seals being dry. You might just be a bit low on refrigerant.

A new Denso compressor is around $200-$300. $900 in labor on top of that is awfully expensive. I would do some research and find an independent car AC shop to trouble shoot and do the repair.

When someone says the AC works great 95% of the time, a brand new compressor really doesn't sound like the most likely culprit, but anything is possible. It's also unusual for a car with such low mileage.

 

Try giving it a bit of a rev. Sometimes that's how my cars cold air kicks in, that only happens sometimes if I was stationery and the temperature outside was hot.

Other than that I'd check the freon, always start with the small things before going into the major stuff. You'll save money and time.

 

Labor to swap out the compressor shouldn't cost more than a few hundred bucks at the most. I recall my tech did the job in about an hour.