GFunkError Posted October 14, 2004 Share Posted October 14, 2004 Ok so when I bought the car, the AC barely cooled. It would cool in the morning but after sitting in the Texas sun all day, it would not cool at all on the evening drive. I was told I would have to replace the evaporator. I didn't since winter was just around the corner. So today it was in the 50's in the morning and the heat won't work either?! The fan works fine...what could it be? Quote Link to comment Share on other sites More sharing options...
Spongebob Posted October 14, 2004 Share Posted October 14, 2004 I have a 92' also, and have never had an issue with heating or A/C. But as it is cooling down now, I went to test the heater and there is no heat at all, but the A/C works perfectly and so does the fan? So I too am looking for a little advice as to the route to approach the problem. Possibly Heater core? Anyone else had this problem? Quote Link to comment Share on other sites More sharing options...
Marty Witt Posted October 16, 2004 Share Posted October 16, 2004 It might be the air mix servo motor. You can run a self diagnostic using the system built into the radio. I forget the sequence of buttons you hold down while turning on the ignition. You should be able to look it up in threads over 30 days old. It could also be the control valve under the hood, passenger side, mounted n the firewall, near the top. It is very easy to reach. You can try swapping the vacuum lines to see if heat comes on. If not put them back the way they were and run the self diagnostic mentioned earlier. When you look up the old threads on this topic, they will list the trouble code that means the air mix servo motor it might be 21, but I'm not sure). My car had A/C but no heat and it turned out to be the servo motor. Lexus wanted over $2000.00 to repair. I did it for the cost of the part, about $125.00 if I remember correctly. If that's what it is, I can post more info on how to repair. Quote Link to comment Share on other sites More sharing options...
Marty Witt Posted October 16, 2004 Share Posted October 16, 2004 Here it is: While turning the car key from off to the start position, simultaneously hold the Temperature control knob and the recirculate button. The system will go into self diagnostic. It will automatically index through the various system settings and flash a code if there is a problem. Mine came up with a code 41, which means there was a problem with the air mix servo motor. If you do the test in low light, you may get a code 21, this is the solar sensor circuit and is nothing to worry about. Try the tests and let us know. Quote Link to comment Share on other sites More sharing options...
LLS Posted October 17, 2004 Share Posted October 17, 2004 just put some coolant in it and top the level all the way off. Quote Link to comment Share on other sites More sharing options...
GFunkError Posted October 20, 2004 Author Share Posted October 20, 2004 just put some coolant in it and top the level all the way off. ← you mean freon? How would that fix the heat? Quote Link to comment Share on other sites More sharing options...
GFunkError Posted October 20, 2004 Author Share Posted October 20, 2004 just put some coolant in it and top the level all the way off. ← you mean freon? How would that fix the heat? ← I also ran the diagnostic and it came back with a 00. Quote Link to comment Share on other sites More sharing options...
SirSam Posted October 20, 2004 Share Posted October 20, 2004 Were are the Low and High Ports to recharge the system on the SC's? I noticed one valve coming out of the top right of the radiator that would use a fitting not sure what that goes to, I need to purchase a Lexus Repair Manual, car was serviced at Dealer its entire life up to 2000 at 79,000miles, so I'm sure it has R134. Quote Link to comment Share on other sites More sharing options...
Marty Witt Posted October 21, 2004 Share Posted October 21, 2004 He did mean coolant, not freon. If your system is low on coolant, it's possible that your engine coolant is not flowing properly. This is what heats the car. Freon cools it. Did you try swapping the vacuum lines on the heater control valve? Quote Link to comment Share on other sites More sharing options...
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