tpete Posted January 13, 2004 Share Posted January 13, 2004 I have a 1996 ES 300 whose climate control periodically "defaults" to 75 degrees regardless of the temperature desired. This can happen at any time and usually lasts about 10-15 minutes before it resets itself back to the requested setting. I performed a self-diagnostic test and came back with a code 21. Any idea as to what this code means? Quote Link to comment Share on other sites More sharing options...
SKperformance Posted January 13, 2004 Share Posted January 13, 2004 where did you find the self diag? the one i listed here i also listed with what all the codes mean? look in the general maintance for other answers if needed. But 21 means the solar sensor which is normal if it is not very bright outside. Quote Link to comment Share on other sites More sharing options...
tpete Posted January 13, 2004 Author Share Posted January 13, 2004 SKPerformance--Thanks for your response. I followed the procedure as outlined in your 6/11/2003 FAQ post. The code 21 now makes sense as I performed the test (pushing AUTO and recirculation buttons while turning key into the "ON" position) inside the garage with very little light. I suspect there is an electrical short/disruption in the climate control system that is causing it to flake out. An annoyance I have lived with for over 2 years. Quote Link to comment Share on other sites More sharing options...
mkyari Posted September 12, 2008 Share Posted September 12, 2008 Hello ALL, I have been a long time lurker and this is my first time posting here and I see a lot of posts on error 21 solar sensor for the HVAC system, but does anyone actually know how to fix it or replace it? Quote Link to comment Share on other sites More sharing options...
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