Multiple Issues That I Need Help Diagnosing

[sanstoetter]

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. 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'm also having issues with a vibration coming in about 65-75mph, that goes in/out staying 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 wheels, and 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

**EDIT** I forgot to mention that the the AC light stays solid now, but there's no difference in power, and no cold air. This happened randomly one day a few weeks later, and I have no idea why.

[steve2006]

You can read the fault codes yourself for the AC then go from there,the high speed vibration could be a number of things but I would start with a front suspension check for worn components.

[sanstoetter]

After reading your post I found the write up on lexls.com, and checked my code... ended up with a beeping 21 and 23 code. I do not see code 23 as a possibility on the tutorial... anyone know what this means? I see that the code 21 reads "Open or short in solar sensor circuit", but I've pulled the codes multiple times, and that's only come up the once. What does that mean, and where would I find the solar sensor circuit?

[sanstoetter]

After reading a bit more today I read that the 21 was due to low light, and after rechecking this morning its gone. To replace the compressor Im asumming that I'll need to empty the R134, replace the compressor, pull a vacuum, and refill the R134... anything I'm missing? How much refridgerant, oil, etc... will I need to fill it back up?

[steve2006]

AC repairs in my opinion should be left to professional AC engineers,the system needs to be evacuated,repaired as required then dried out,filled with an inert gas/dye to check for leaks and only when everything is good refilled with refridgerant/pag oil.

If you lift the hood and then run the engine with the AC on you can see if there is gas in the system by looking at the AC inspection window to the left of the radiator,you should see a gas cloud in the window.

When the AC is switched on the engine idle speed should rise and listening from the front you should be able to hear the compressor coming on and off,the cooling fan should also cut in and out.

[sanstoetter]

AC repairs in my opinion should be left to professional AC engineers,the system needs to be evacuated,repaired as required then dried out,filled with an inert gas/dye to check for leaks and only when everything is good refilled with refridgerant/pag oil.

If you lift the hood and then run the engine with the AC on you can see if there is gas in the system by looking at the AC inspection window to the left of the radiator,you should see a gas cloud in the window.

When the AC is switched on the engine idle speed should rise and listening from the front you should be able to hear the compressor coming on and off,the cooling fan should also cut in and out.

I have experience working on other vehicles AC, and I know that I do not have a leak as it's the pressure has not dropped. I also have the tools to pull a vacuum before refilling, but I do not have an FSM or anything detailing the capacity of the AC system. I'm just looking for specific details related to this car.

[billydpowell]

I have experience working on other vehicles AC, and I know that I do not have a leak as it's the pressure has not dropped. I also have the tools to pull a vacuum before refilling, but I do not have an FSM or anything detailing the capacity of the AC system. I'm just looking for specific details related to this car.

if you do , you know to fill it until the window clears....

[sanstoetter]

I plan to, but I'd like to buy roughly the right amount of refrigerant rather than have to return later on.

[TA in KC]

Is there not a label somewhere in the engine compartment that specifies the refrigerant capacity? I know on my previous 92 LS, there was a yellow label right on top of the condensor fan that specified the capacity. I believe it was a little over 2 lbs.

[sanstoetter]

I looked for a label without any success, but I did end up getting the A/C working correctly. I replaced the compressor, pulled a vacuum, used ~3.5 12oz cans of R-134, and a small can of UV dye to diagnose if I have any leaks.