Why no heat on a 6cly 1996 B2500 Dodge van. I changed the thermostat all it does is blow cold air.?

Answer 1

I had a similar problem with an older (1986) Dodge van. I tried a new thermostat changed the coolant, even blocked the grill opening on the front of the van - and
still had almost no heat.


First determine if the engine is actually heating up.
Do you have enough coolant in the system? Check it cold.
The heater core is the highest point in the coolant system and the first thing to run dry.


Is the temp gage moving up?
If not, your thermostat may be bad .


After the engine has been run 10 minutes or so and is warmed up
Feel the upper radiator hose (with the engine turned off)
is it hot? If it is, the engine thermostat is working.


If you have heat there and not in your heater a couple possibilities are:


1. Check the cable (under the hood on the heater box) that moves the flap
the adjusts the temperature from the lever on your dashboard heat control.
There is a clip that holds this cable down to the heater housing.
I had one where the cable was clamped down in the wrong position
and it was not allowing the cable to push the lever all the way.
a. Move the temp adjustment lever on your dashboard all the way over to hot.
b. Under the hood - at the other end of the cable: look at which way the cable
moves the lever on the heater box
Loosen the clip that holds the cable enough so you can slide the cable
in the clip, then see if the lever moves farther in the direction it should go.
It may sound stupid, but I wish I had checked this first on my van.
....and it doesn't cost anything to check it.


2. Make sure the heater hoses going to the heater core are not kinked.
This will restrict or stop the flow of hot water through the heater core.


3. I don't know how many miles are on your van - but the heater core
can be clogged or damaged (i. e. corrosion) and will not flow water through.
If it's clogged, a reverse flush of the coolant system might solve the problem.
If it's corroded it will have to be replaced.


I hope this gives you some starting points -