heater?

Bad thermostat?

If the coolant temperature is registering as normal on the instrument panel, then check to see if the heater control valve on the firewall in the engine compartment is opening. If the heater control valve is opening, then you will need a repair manual to diagnose the auto AC system.

Also check coolant level in the coolant overflow bottle.

If the coolant temperature is not registering as normal, the thermostat may be stuck open.

1. Check radiator fluid level. If the level is low, there's not enough hot fluid going to the heater core, hence no heat. I've had this happen on a couple older units where the radiator cap had gone and I hadn't known it.
2. Watch your temperature guage. Does it move up to 40-50% of scale when it warms up and sit there. That is normal behavior. If it doesn't 'warm up' then you've got a bad thermostat.

Also, if your fluid is low, check for leaks. If you replace the thermostat, have the fluid changed and have it CHECKED FOR LEAKS and have the cap tested for pressure. It's not good to have no heat in the middle of 0 degree weather. My dad's thermostat blew out on his 77 in the middle of winter one day and we replaced it the same day and that fixed the problem.

Charles of Schaumburg