I have a 1984 Dodge Rampage, Base, 2.2. The air conditioner sometimes comes on when it is turned off or set to "vent only", and sometimes does not come on when turned on. Sometimes, it will come on after driving several miles, as if needing to heat up. Blower works as it should when turned on. Is this controlled by the computer? What else could cause this? The unit is upgraded to R134 and the compressor is new.