Er? Auto but only use the A/C part when too hot. this is a classic case of not describing the chain of events.
Auto = A/C system + heating all the time so if you have it on auto and the windows open you are wasting fuel and any effect the filtration process the A/C might give you.
However, if you only have the HEATER on for your legs then the A/C system hasn't been run for ages and that more than likely the problem. If the A/C compressor isn't used the seals go hard and the GAS will escape causing a drop of pressure and no COOLING. A/C gas is a liquid when under pressure and a gas when the pressure is released. When a liquid it is hot and when the liquid turns to a gas it "boils" @ - 20C and in order to boil it must take heat from what is available such as the surrounding air just like you boil water on a gas or electric cooker ring/hob - apply heat and the water boils @ 100C.
If the A/C hasn't been used for some time - overworked (with the windows open) or not serviced (re-gassed and checked for leaks) then it's a 10:1 chance that there is no gas in the system and if that's the problem get the condenser checked for leaks, Check the large fan in front of it is actually working (they do seize often) when the A/C is on and change the Filter/Drier unit too.
Can cost $$$$$ but worth it - and make sure the A/C pump compressor clutch it also working - low pressure will lock it out of action as will a damaged coil and contacts. Last Fall (Autumn) my compressor clutch actually disintegrated!!!!!!!!!!!!!
YES -------- BANG Kerrunchhhhhhhh! "£800" GB pounds in total.
Sir Hugh of Bognor
The difference between men and boys is the price of their toys. Intelligence is not knowing the answer but knowing where and how to find it!
Hugh Gundersen snipped-for-privacy@h-gee.co.uk Bognor Regis, W.Sussex, England, UK