Climate Control problems with a 2002 Honda Odyssey

We are the original owners of a 2002 Honda Odyssey (80k miles) that we believe has climate control problems.

For the first 4-5 years, the climate control worked great. We usually had controls set to “Full Auto” (as recommended) and temp at 72 degrees. In warmer weather, when the van interior temp was high, the fan would kick into high gear and start blowing cold air within a couple of minutes.

Now, when the van is started up in warm/hot weather, the climate control (in Full Auto at 72) is AWOL. The fan doesn’t kick into high gear nor is the small amount of air being circulated cold.

We’ve tried setting the temperature to the coldest setting and fan at the highest setting (overriding Full Auto). Sometimes this works, but other times it makes the problem worse with no cooling at all. (Exhibit 1: 3-hour mostly freeway drive, 90 degrees outside, 108 degrees inside the car, miserable dad, mom, and 2 boys.)

If we leave the climate control set to Full Auto, the car will slowly cool down and after about 20-25 minutes the interior temperature is comfortable. In most cases, we’ve reached our destination by then (albeit very sweaty).

We’ve taken the van to the dealer and an independent mechanic four times regarding the climate control problems. The dealer checked the AC refrigerant and it was fine. They checked the AC by measuring the temperature of the air coming out, and they say it works fine.

It eventually sorta works fine, but does not work like it used to and does not work satisfactorily.

It seems as if the problem is either sensors or the computer. Any suggestions on what I should ask a mechanic to examine?