A/c Clutch Not Engaging.......electrical?

[weazel8]

I just recenlty bought a 1991 LS400 with 189,000 miles. I bought it knowing the the A/C didn't work. I had a local shop look at it and they said the clutch isn't engaging on it and it is an electrical problem. They cant fix that and told me to go to the dealership. I know that will cost an arm and a leg. Is there anything I can do myself?

[RFeldes]

I assume your freon level is okay...if it is low or empty the clutch will not engage.

With the ignition off apply 12V to the connector on the top of the compressor and see if it engages. If not then your clutch needs to be rebuilt or replaced. If it does then you may have to replace the pressure switch or ECU.

[SKperformance]

Look in the general maintance for the diy HVAc control codes.

[weazel8]

I had Lexus look at my care today. They told me the same that my clutch was not engaging. They recommended that I first try and replace the clutch and if that doesn't fix it then replace the compressor. The problem is $500 for clutch replacement and $1400 for compressor. I called the local auto parts store and can get a clutch for $120 that is rebuilt. Is this pretty easy to replace. I have already replaced the fan bracket in this car so I have done some work under the hood. Also anyone have a tutorial for the clutch replacement

[SKperformance]

Since you are handy i would spend $10 or so and download the full Lexus manual from Toyota online.

I can't remember the link to get it from there site though.

[LScott400]

Click Here and check out option number 6.

[weazel8]

Does anyone know if you need a special tool to do this?

[Robert Young]

On possibility is that the clutch is worn enough that the electromagnetic force is not stong enough to pull the clutch plate across the gap. I've seen this frequently with Nippon Denso AC units on Ford products and the unit (also Japanese) on our Volvo S90. The interesting signature for this problem is that the AC works fine while the car is cold (shortly after starting) and then cuts out when the engine bay warms up (worse when outside weather is also hot). As the clutch is frequently cycling on most modern AC designs, not too surprising that clutch wear is a problem on cars with automatic temperature control, etc. One temperary (one to two years or so) fix is to re-shim the clutch plate gap, I've found I can generally do this on the car (may be difficult, require tool development, etc.). Unfortunately, I don't find specifications for this gap in the Lexus manuals, they simply instruct you to replace the compressor / clutch assembly if there is a problem with either!!

At the $120 price noted for a new clutch, I'd certainly go that way if there is no indication of a leak (I need one for our Volvo that will be at least $250). Make sure you check for instructions on clutch plate gap, to ensure longest life I'd set it too the low end of the range.