Air Conditioning - Are you smarter than my A/C guy?

I'll come home, the house is hot, no A/C. I called the A/C guy and he can't find the problem. HOWEVER, I can make it start working, first time, every time by doing this: I turn the A/C off. I turn the fan from AUTO to ON. After about 15-20 seconds, the fan starts blowing. I switch the fan back to AUTO and turn the A/C on and it immediately works fine for anywhere from 1-10/20 days. The reason I tried this in the first place is I thought the coils might have frozen but it always starts in about 15-20 seconds so it can't be defrosting that fast. Anybody out there smarter than my A/C guy?

When it quits is the ourdoor section still running but the indoor fan is not?

In response to your thread title: Is he a 5th grader? :D

What did he do? - just say he hasn't a clue and then leaves, and that's it?

Sounds like some relay component that can start the fan okay in ON, but not in AUTO. I think the fan speed is the same for a/c AUTO, as it is for fan ON(irregardless of heat/off/cool setting), so I doubt there is fan speed issue. Besides, then what would make it continue to work once you shifted it back to AUTO?

Interesting how you stumbled upon this little secret, to get it to go in AUTO, unless there is some kind of coincidence going on.

It be nice to see a picture of your wiring diagram.

Have you checked your thermostat ? is it pretty old ?

Have you checked your thermostat ? is it pretty old ?

I guess that WOULD be the easiest place to start, actually.

I would chk the stat as well

Thanks for your help. The thermostat was put in when the house was built 33 years ago. I'm going to get a new one this weekend.