I have a 2002 Odyssey, the air suddenly quit working, the blower would turn on, but it would only blow hot air and would only blow when you turned the manual fan control all the way to the max. Took it to the shop and they replaced the expansion valve, now the air is blowing cool, but the automatic control is still not working. I still have to turn the manual fan control all the way up and blast the cold air out. Has anyone had a similar situation?

 

Check the transistor (or resistor depending on LX or EX trim).

 

I had the same problem - if the fan only works on the MAX setting replacing that overpriced Honda transistor fixes.

It is located under the dash and has some big cooling fins that actually sit in the air flow.

Buy a replacement for it first and you'll see exactly what it is that you are looking for under there. Replacing it is an easy job.