2000 Mercury Cougar • 190 miles

My A/C, and Heater do not blow either cold, or hot air. The fan works fine and it seems like the vent doors move properly for defrost, floor. Etc. At one point my car would overheat so I changed the thermostat. Fixed the issue with over heating. Another time my heatercore was leaking so I replaced that. Randomly sometimes luke warm air will blow out to my after the heatercore replacement but it didn't fix the heating issue. About 6 months ago when I would turn the defrost on, my rpms would rise and continue rising to about 3000-3500 rpm with the car in neutral, so I couldn't turn the defrost on while I was at a stand still. I haven't done anything to the system and now I can turn the defrost on without the rpms rising. Coolant levels are fine. Im sure there are probably multiple issues with the A/C and the heating units but I really don't know what to tackle next. Can someone help? I am tired of not having A/C in the summer and no heat in the winter.
March 25, 2013.

Do you put a proper temperature thermostat in? You also need to check the Freon level and the AC. You probably have a leak.

Mar 26, 2013.