I have a 2006 Impreza with just under 100k miles that I have owned since new. On a trip through the South in 100 degree weather last week the air conditioner suddenly started blowing hot (and humid) air. We found a Subaru dealer in Memphis, about an hour away. They looked at it and told me that I needed a new evaporator switch(P/N 72166FE010). They did not have one, and we were on the way to New Orleans. Got one ordered to ship to the dealer in New Orleans. Memphis dealer says its a simple plug in. Drive to New Orleans, the A/C works fine during the trip!! Find the Subaru dealer in Metairie, just outside NO. They look at it and tell us that it will be $1100 labor to install the part. Decide to pass on that. At the same time our aftermarket gas cap has been leaking and turing on the check engine light. Replace with OEM cap. On the way home to Colorado. A/C works fine when you first start out. After 20-40 minutes, air flow diminishes and air gets gradually hotter. Fiddling with it we discover that if the A/C button is turned off for a few minutes, it blows cooler air, then back to outside temp air. Then, push A/C button and it works great for another 30 minutes or so. This gets us home through temps as high as 113 degrees. Back in cool Colorado, it still does the same. Ideas?