Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

No heat

What could be why I have no heat it’s getting cold and trying to figure out why and the AC/ heat does blow out the dash panel on out floor or defrost and when heat on its cold air blowing

If the fan is on and only cold air is coming out of the floor/defrost, check the level of antifreeze in the radiator and overflow. Only do this when the car is cooled off. If the level is low there is no hot water going to the heat exchanger. If the fluid level is OK the heater core may be blocked. What make of car, mileage, check engine light on ? Did the AC work in the summer?

Some cars also have heater control valves that are designed to cut coolant flow through the heater core when no heat is called for. The control switches can go bad and not open the valve, causing the same problem. Knowing the make, model, year, and engine option can help us help you.

As stated, some cars use a “Heater control valve” that uses a vacuum command from the control panel to divert the flow of hot coolant to the heater core. Others use a “door” to divert the hot air from the heater core to the vent system. If either one is not working, you won’t have enough heat. if any air is only coming from the defroster or bottom outlet regardless of the commands you gives, than a switch problem in your heater control panel may be the issue. Look for your heater hose going to the “fire wall” to see if there two heater hoses connected to a valve with a vacuum hose attached. If you do, have someone slide the temp. control from cold to hot and see if the lever on the valve is moving. You should also feel both hoses to see if they are both hot. If one is hot and the other is cold, a plugged heater core or bad valve could be the issue. YouTube is a great place to get tips on flushing the core (and the whole cooling system) as well. Good luck!

As stated, different vehicles use different methods to control the ventilation system.

So without knowing the year/make/model of the vehicle, nobody can really answer your question.


Your heater control valve is clogged with missing punctuation marks.

You post is a little difficult to understand. You could have a stuck open thermostat. If your car has a dashboard coolant temp gauge, where on the scale does the needle point after driving for 5-10 minutes?

We changed out the thermostat it was bad but we have no heat still only blows cool

My vechile is 2002 lincoln navigator the ac works only on defrost/floor doesnt come out of the pannel vents. The heater control are with the push of button that you turn the temp up on thanks everone for all help

Matt i have a door not the heater control vaule also do you know if i have to pull the whole dash out to change it 2002 lincoln navigator

Could be as easy as a vacuum hose left off or cracked.

It could also be the blend door actuator. It’s an electric control, not vacuum actuated. A good way to know if the heater core is blocked up is to start the engine from cold and monitor the two heater hoses. If they both get warm together, the heater core is fine. If one gets warm and the other stays cold, the heater core is plugged up.

You may flag this as off topic, but with a screen name Supersavermom what the heck are you doing with a Navigator gas guzzler?

I have five kids and its about the same gas as a van nut I got to honestly say I get pretty good gas miliage

If its the blended door do you have to pull the whole dash to change it

@VOLVO V70, maybe it’s a sarcastic nickname. Remember Tommy ‘Tiny’ Lister?

Might I suggest a sweater?

How did you purge the air out of the system after changing the thermostat?
Your heater control valve if closed will prevent you from purging the heater core, and that could be your problem… an air bloc in the heater core.

Could also be a blocked/clogged heater core.

There are other possibilities, of course, such as a malfunctioning valve. How have you tried to verify that hot coolant is flowing through the heater core? Have you checked the upper and lower hose temperatures?

Have you had cooling system problems lately, or other operating problems? They could provide clues.