1991 Blazer S-10 wont start.

I can feel it once in awhile but it seems like it was alot faster before becuase I dont feel the engine bog down as much. I just got in it one day and was driving down the road and had nice cool air and then when slowing done for stop light the air got warm and then after moving a bit it got cold again. Any ideas. Someone said the evaporator may be freezing. Also I read an article here that said something about a clutch in the unit. Someone said this has happened because I didnt turn my air unit on in the winter time and let it oil its self.

Can you hear the fuel pump running when you first turn the key on?
If not then check the relay first and if it has voltage then it is likely the fuel pump is bad.

If you can hear the pump running when you first turn the key on then loosen the line on the left rear (as you face motor from the front) line to see if fuel runs out when you turn key on. If not then check the fuel filter.