For the heater, once the engine is warmed up, feel the two heater hoses under the hood. They should be too hot to hold onto for very long. If they are not hot, either the heater core is plugged, the coolant level is low or there is an air pocket that hasn't burped out yet. If they ARE hot, suspect a problem with the doors and actuators inside the heater box in the dash.
The AC compressor won't turn on if the refrigerant charge is low. That is done to prevent the possibility of sucking in moisture with outside air if there is a leak. Moisture from humidity in the air and traces of remaining refrigerant combine to form hydrochloric acid. That's why mechanics always suck the system into a vacuum to remove any moisture before adding refrigerant.
First they will check to see if the charge really is low. If it is, they will add just enough to run the compressor so they can search for a leak. Due to the age of the car, there may not be a leak big enough to find and repair. The refrigerant could have likely just leaked out slowly over time. That is common. If that is the case, recharging the system will restore it to normal operation.
Tuesday, May 10th, 2011 AT 3:26 AM