DIAGNOSING A/C PROBLEM

  • Tiny
  • pamla
  • 1998 Lexus GS 300
  • 118,000 miles

My 1998 Lexus GS 300 is blowing hot air. The "freon" is full. The clutch is working as well as the fan. I tried to find the expansion valve to check whether the line is hot before and cold after but I am unsure if I found it. I found one object that may be it, and, if so, this may be the problem as the line before is warm and the line after is just an itty bit cooler. The temp gage does not show car is overheating. I tried to find the evaporator to check the temp of the lines. Can you provide any other diagnostics I could perform to determine the problem? Also do you have a diagram so I can figure out where everything is located. Also, can you tell me how to remove the filters so I can check them? Thanks so much for your help.

Tuesday, September 27th, 2011 AT 6:40 PM

2 Answers

  • Tiny
  • ASEMaster6371
  • Expert
  • 25,502 posts

You need a set of gauges to monitor the pressures. Feeling the lines is no indication of much.
It could be a bad compressor, bad dryer or a bad expansion valve. First thing you need to do is see about the freon. There is no visible way or gauge check to indicate freon level. We remove it and see how much was recovered, then we determine how much is required and move forward. It is a process done by someone familiar with ac systems. I dont think there is much you can do without equipment.

Roy

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Tuesday, September 27th, 2011 AT 6:54 PM
  • Tiny
  • Wrenchtech
  • Expert
  • 19,542 posts

You can't know anything until to take both high and low pressure readings on the system. Post them here when you get them.

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Tuesday, September 27th, 2011 AT 6:54 PM

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