mohitlad Posted June 8, 2005 Share Posted June 8, 2005 I have a 1992 SC 400. Had it for a year with about 105k miles on it. Since last week, the heating does not work. Ran a diagnostics, and came up with code 21. Funny thing is that the heating works only when I turn the knob to MAX_HEAT. Even one unit below that will blow cold air. Any suggestions on what to do would be helpful. Thanks Mohit Quote Link to comment Share on other sites More sharing options...
Marty Witt Posted June 8, 2005 Share Posted June 8, 2005 I have a 1992 SC 400.Had it for a year with about 105k miles on it. Since last week, the heating does not work. Ran a diagnostics, and came up with code 21. Funny thing is that the heating works only when I turn the knob to MAX_HEAT. Even one unit below that will blow cold air. Any suggestions on what to do would be helpful. Thanks Mohit ← Code 21 is the solar sensor and most likely means it was dark when you ran the test. My car did not blow heat also. I found that by adding a little coolant to the system (even though it appeared full) made my problem go away. It's real easy to try it. Quote Link to comment Share on other sites More sharing options...
AppleJack Posted June 8, 2005 Share Posted June 8, 2005 I've got the same car - same year .. and have had that same problem .. sorry to say I don't have a solution for you. Mine seems to be intermittent and actually hasn't had that problem for a while ... I checked the coolant level to make sure that wasn't related. Good luck and I'll stay tuned to the responses you get ... Quote Link to comment Share on other sites More sharing options...
mohitlad Posted June 14, 2005 Author Share Posted June 14, 2005 I've got the same car - same year .. and have had that same problem .. sorry to say I don't have a solution for you. Mine seems to be intermittent and actually hasn't had that problem for a while ... I checked the coolant level to make sure that wasn't related. Good luck and I'll stay tuned to the responses you get ... ← Ok, thanks for the tips. adding coolant seems to do the trick. I am not sure if the air is as hot as it should be, but it is definitely warm. Thanks Mohit Quote Link to comment Share on other sites More sharing options...
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