My 200k 94' LS400 has been giving me a few issues over the past year, and I'm finally getting around to working on them. About a week after purchasing the car (11/01/2009) my AC gave out on me. When the AC would cut on the car felt like it lost power, and 5-10 seconds after that the AC light would start blinking and the power would come back immediately. This continued happening for a few weeks, and now the light will stay solid but the compressor never kicks on. I bought an R134 refill with a gauge, and when I hooked it up the pressure seemed right so I left it alone. I kinda assumed that the compressor locked up, but I wanted to know if there would be a good way to diagnose before just replacing it. I did use the lexls.com tutorial for AC diagnostics, and came up with a code 23. I do not see code 23 as a possibility on the tutorial... anyone know what this means? I'm also having issues with a vibration coming in about 65-75mph, that goes in/out while driving at a steady speed. This issue has been there from the beginning, and since Ive had the tires balanced, and eventually had new tires mounted/balanced. While they were being balanced I looked for any bends/flat spots in the rims without finding any. You can feel the vibration in the steering wheel, and in the seats... doesn't seem to be in only the front or rear wheels. I'm wondering if these cars have a center support on the driveshaft, or if they have a replaceable U-joint? While I'm working on it this weekend I'd like to at least diagnose that issue as well. Any help would be greatly appreciated.



Thanks,

Steven

 

When you hooked up the pressure gauge, what was the pressure in the system?
This is info from my 93 manual;

The code 23 is "Pressure Switch Circuit"
Open in pressure sensor circuit
Abnormal refridgerant pressure
(below 28 psi or above 455psi)

TROUBLE AREA
pressure switch
Harness or connector between pressure switch and A/C control assembly
Refridgerant pipe line
A/C control assembly

If you need it, the pressure switch is located behind the passenger headlight.

The vibration; The driveshaft (actually called Propeller shaft) does have a support bearing which wears out. Mine is shot and I feel the vibration in the seat and on the floor at my feet. I know the propeller shaft needs to be balanced and there are different weights to put on it. Here's a link to the parts of the propeller shaft. Hope it helps ya out. http://lexus.sewellparts.com/oem-cat...S400-1994.html

 

Thanks for the info... I ended up just under the pressure limit, and once I went over that the compressor tried to turn. The compressor was locked up, but I replaced it with a working one. Filled it with R-134, and a can of UV dye to diagnose where I have leaks, but right now it working as long as it doesn't drop below that pressure.