- No/insufficient heat or defrost -
low or high refrigerant charge, clogged radiator/heater/core or kinked hose, blower motor/fuse/switch/wiring or ground, heater control valve, temperature/vent level binding/broken, air lock in system, computer related.

- Heater blows hot and cold -
air lock in system.

- No air conditioning -
low or high refrigerant charge, blower motor/fuse/switch/ wiring or ground, temperature/vent level binding/broken.

- Insufficient air conditioning -
low or high refrigerant charge, blower motor/fuse/ switch/wiring or ground, heater control valve, temperature/vent level binding/ broken, computer related, slipping belt, a/c clutch/fuse/switch/ wiring/ground, restrictions in condenser.

- Mildew odor -
clogged A/C drain.