My heater is not working?

check blend door operation it's up over gas pedal area of HVAC.

Thanks fixitmr...I'll see if I can check it tonight and let you know.

Hi guys. Once you figure out the mode operation, there was a common problem that causes it to blow only cool air. The clue is that both heater hoses are hot so you know it's circulating hot coolant and should be blowing hot air. An additional potential clue is you won't hear the nice "thump" of the temperature door when you slide the temperature lever back and forth.

If the air doesn't switch to different outlets, look for a broken or disconnected vacuum hose under the hood. When the vacuum supply is lost to the heater controls, the system is spring-loaded to go to defrost so even though your feet might freeze, the windshield will be clear.

Well, I checked the blend door & it works fine, I can hear the thump. Come to find out that someone had replaced the heater control valve a while back (it's my sister's van and she couldn't remember when she got it worked on), but there seems to be an extra vacuum hose that comes out of the firewall and plus into nowhere, so I'm assuming that the line that's messing up her heater operation. The other hose that comes from the firewall connects into the control valve and it you can see that it opens and closes the valve as you turn heater off & on. Now i have the task of location a diagram that shows where all the hoses are supposed to connect. One odd thing.....I switched the hoses to go into control valve to see what would happen. When I connect the one I found loose into the control valve some heat does blow from defrost vents but doesn't operate the valve. Other than that still no air from other vents. Still searching.....

Heater problem
1990 Dodge Caravan 6 cyl Two Wheel Drive Automatic

my heater was working fine one day then get in it the next day and it wont work. we changed the fuses and had the blower motor checked it isnt any of these, but the heater still will not work. what else could be the problem for the heater not to work? i have tried everything i could think of, what else could it be

HI there,

Check that the hoses for the heater core are hot to touch, if both are not, the heater tap or controller has failed or the core is blocked, start here.

mark (mhpautos)

I have a 1986 dodge caravan with a 2.6L mitsubishi engine. I changed the thermostat twice last week, bled the heater core, and the radiator is full. The engine runs cold and I have little or no heat. What is the problem, I'm out of ideas.

Pinch the upper radiator hose closed to see if the temperature comes up. If it does, the new thermostat is not sealing.

You might want to use a thermometer to verify engine coolant temperature is really low. If it is up to 180 to 190, the heater core could be plugged. It's pretty common to have to back flush them with a garden hose.

Even after running for some time (enough for engine to be up to temp), the temp gauge barely reads above cold and the heater puts out luke warm air at best. When I turn the heater off, the temp guage rises slightly.
With the engine cool I opened the radiator, but it would not take anymore fluid.
Is this a thermostat problem? If so, where is the thermostat on this vehicle (I've changed others in the past)?
Is it a heater core issue? If so, how do I flush it?
Or is it possibly just a coolant level issue? The fact that it won't take anymore concerns me. Or is that because I checked it while it was cool?

Any advice is appreciated. Thanks.

you have to drive it for a while at higher speeds to see if its the thermostat. if it is it would be overheating on you.

they sell stuff at autopart stores made to flush the coolant system. besure to bleed the system of air when you are done.

I drove it the other night for about 25 min's at highway speeds, the temp guage barely got above the cold mark, the heater put out only luke warm heat, but the engine didn't appear to be overheating. Does that help you narrow in on the problem? Thanks.