airconditioning problems

[carlsaturn]

it seems my air conditioning goes crazy on long trips. in town it does ok. on a long trip of driving,mostly highway, the blower gets very low even on high and the tempture {coldness}drops off extremley. stop, shut it off for a while and everything is back to normal unless it is driven on a long highway drive. whats up with this thing? does it need freon? if so why does it do fine around town? and why does the blower power get low????

[Classic boy]

It sounds like the evaporator is freezing up, not that uncommon on auto aircond systems. The TX valve is probably throttling the temp too low. You can compensate by setting a higher temperature and running the fan higher to prevent ice up. Also select outside vent to get warmer air thru the evap.
A lot of people find it hard to believe that ice on the evap will actually make the system run warmer because ice is actually quite a good insulator. That's why eskimos use it to make igloos.

[losttourist]

I had that problem last summer , got the car checked out and the dealership could not find a problem. This summer everything worked well. However we are now at the end of a trip from Ontario Canada to Orlando Florida and the AC has given us this problem. I will try the suggestion you have given by setting a higher temperature. Hopefully on the trip back up the ac will work accordingly. Its very hot right now in Orlando.