I usually drive around with the windows open unless I'm on the interstate or it's just too dang hot for open windows and today was a 'too dang hot' day, so I turned A/C on for first time since...last summer, I guess. Anyways, no cold air so I did the self-test and got the code 051 which is not listed in the table of codes. Then I read that if the car's interior is above 90* the self test may be invalid...it's possible the temp inside the car was >90*, so will do another self-test later this evening to see what code shows up. Also, just prior to doing the self test I had an 'ah, yeah' moment and remembered the last time I tried to use heat (several months ago) it was just blowing air and was not warm/hot at all.