The A/C is blowing HOT air in my 1996 Dodge Ram 1500 Pickup. The A/C compressor is running, the suction line cools and sweats, the charge and pressures look good. Our family business is mechanical contracting, so I had one of our A/C techs put a set of gauges on the system and he said everything looked okay, that the A/C was working.

What seems to be the problem is that the HEATER is also ON, thus the hot air. Is this possible? If the engine is COLD, I can start the truck and the A/C blows very cool air. After a few minutes, (when the water temp rises) it turns hot. The compressor is NOT kicking out on low/high pressure.

About the time that this starting happening, I noticed the my temperature control knob has a "rough" spot when turning it through the range. Could this be related?

Is there some type of baffle that deverts air through the heater coil? How can I locate or test it?

Thanks for any help.