Arklahoma Posted August 16, 2008 Share Posted August 16, 2008 I bought a 1991 LS400 about four year ago. AC didn't work at all. I recently had the AC controller LCD repaired. I can read it now. After troubleshooting with a friend we determined that my compressor was bad. This week I replaced my AC compressor and receiver/drier, we also did a good vacuum on the system and recharged with R134. The compressor is not getting any power when you turn on the AC at the dash. When you hotwire straight from the battery to the clutch it engages and blows nice cold air now. Additional problem is neither of the front cooling fans engaging either unless you hotwire them. My friend tells me at least one of the two fans is supposed to run whenever the clutch is engaged. Anyone else had this electrical problem before? I'm pretty confident all my fuses and relays are good. Could use help in what to check next. I know I could take it to the nearest lexus dealership but their kinda expensive. Any help would be greatly appreciated. Quote Link to comment Share on other sites More sharing options...
IS400 Posted August 18, 2008 Share Posted August 18, 2008 I bought a 1991 LS400 about four year ago. AC didn't work at all. I recently had the AC controller LCD repaired.I can read it now. After troubleshooting with a friend we determined that my compressor was bad. This week I replaced my AC compressor and receiver/drier, we also did a good vacuum on the system and recharged with R134. The compressor is not getting any power when you turn on the AC at the dash. When you hotwire straight from the battery to the clutch it engages and blows nice cold air now. Additional problem is neither of the front cooling fans engaging either unless you hotwire them. My friend tells me at least one of the two fans is supposed to run whenever the clutch is engaged. Anyone else had this electrical problem before? I'm pretty confident all my fuses and relays are good. Could use help in what to check next. I know I could take it to the nearest lexus dealership but their kinda expensive. Any help would be greatly appreciated. Disconnect the connector to the ac clutch and put a meter on the side coming from the car (ac button) and see if you are getting voltage. What is the voltage if you are? The connector there is prone to corrosion and VERY hard to reach, so make sure your smallest hand friend is available to clean those contacts! (I am a girl and it was tight even for me.) Remember that the computer will not allow the clutch to engage if it does not see adequate ac coolant pressure. My next question is if you got the oil charge right. 6 OZ of oil I believe is factory spec. Unless the compressor came with the oil aready in it of course.... Quote Link to comment Share on other sites More sharing options...
pishta Posted August 18, 2008 Share Posted August 18, 2008 I bought a 1991 LS400 about four year ago. AC didn't work at all. I recently had the AC controller LCD repaired.I can read it now. After troubleshooting with a friend we determined that my compressor was bad. This week I replaced my AC compressor and receiver/drier, we also did a good vacuum on the system and recharged with R134. The compressor is not getting any power when you turn on the AC at the dash. When you hotwire straight from the battery to the clutch it engages and blows nice cold air now. Additional problem is neither of the front cooling fans engaging either unless you hotwire them. My friend tells me at least one of the two fans is supposed to run whenever the clutch is engaged. Anyone else had this electrical problem before? I'm pretty confident all my fuses and relays are good. Could use help in what to check next. I know I could take it to the nearest lexus dealership but their kinda expensive. Any help would be greatly appreciated. Disconnect the connector to the ac clutch and put a meter on the side coming from the car (ac button) and see if you are getting voltage. What is the voltage if you are? The connector there is prone to corrosion and VERY hard to reach, so make sure your smallest hand friend is available to clean those contacts! (I am a girl and it was tight even for me.) Remember that the computer will not allow the clutch to engage if it does not see adequate ac coolant pressure. My next question is if you got the oil charge right. 6 OZ of oil I believe is factory spec. Unless the compressor came with the oil aready in it of course.... Yes, I agree with the diagnostics not allowing the AC to engage. Make sure you plugged in all the sensors associated with the new compressor and check the pressure. The AC light will flash if you have any diagnostic errors. Quote Link to comment Share on other sites More sharing options...
Arklahoma Posted August 19, 2008 Author Share Posted August 19, 2008 I bought a 1991 LS400 about four year ago. AC didn't work at all. I recently had the AC controller LCD repaired.I can read it now. After troubleshooting with a friend we determined that my compressor was bad. This week I replaced my AC compressor and receiver/drier, we also did a good vacuum on the system and recharged with R134. The compressor is not getting any power when you turn on the AC at the dash. When you hotwire straight from the battery to the clutch it engages and blows nice cold air now. Additional problem is neither of the front cooling fans engaging either unless you hotwire them. My friend tells me at least one of the two fans is supposed to run whenever the clutch is engaged. Anyone else had this electrical problem before? I'm pretty confident all my fuses and relays are good. Could use help in what to check next. I know I could take it to the nearest lexus dealership but their kinda expensive. Any help would be greatly appreciated. Disconnect the connector to the ac clutch and put a meter on the side coming from the car (ac button) and see if you are getting voltage. What is the voltage if you are? The connector there is prone to corrosion and VERY hard to reach, so make sure your smallest hand friend is available to clean those contacts! (I am a girl and it was tight even for me.) Remember that the computer will not allow the clutch to engage if it does not see adequate ac coolant pressure. My next question is if you got the oil charge right. 6 OZ of oil I believe is factory spec. Unless the compressor came with the oil aready in it of course.... I checked for voltage on the side coming from the car. I got zero volts. I used 6oz Ester 100 oil which is compatible with R12 and R134. I now plan on looking for the pressure switches. Quote Link to comment Share on other sites More sharing options...
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