OT...Dodge 2500 not blowing hot air

OK, I have a 97 Dodge 2500 4x4. Turn the defroster or heat on and it blows cold air, not frigid cold, but definitely not warm or hot.

When I first start the truck and drive it, the temp guage will run straight up to 220* and then immediately drop to 190*...which is what the thermostat is.

Why is it not blowing warm/hot air? Is it the thermostat, heater core or ??? Trying to figure out where to start.

THANKS guys!!!!!!

Check the coolant level first.

My 99 v10 will do that when she is trying to tell me to add water

Years ago you had a supply line and return line from the heater
coil inside the cab. The heater control was mechanical....cable
from inside cab to butterfly flow valve in one of the
lines....supply I guess under the hood.

If that valve stuck closed, like would happen in the summer with
no use, you would have the problem mentioned. Problems I had
I noticed that the cable would move, the cam on top of the valve
would move, but the connection between the cam and the shaft
that led to the butterfly that controlled the flow had broken.
Butterfly was frozen closed and hence no hot water flowing
through the heater radiator in the cab. New inline valve solved
the problem.

HTH,
Mark

Install a politician

Cute and a lot of truth to that.

BILs Dodge V10, the thermostat broke, so not only was it not moving, it was always restricting the flow! Replaced it and he could not get it cool enough!

new to you truck or one you have had and used the heat before?

can remember buying vehicles with faulty cores and people would bypass them int he engine compartment.

I have owned two different Chrysler products which developed that problem. Neither of which had the same engine as your truck. But, as you stated, the temp gauge would flux. from hot to cool and little or no heat. Each time this happened which was every year or every other year, I would install a new thermostat and that would fix the problem.
That being said, if the controls are electrical, that could be a problem or being a 97, the heater core could be restricted, but I believe a thermostat would be the easiest and less expensive place to begin.

My thoughts exactly!

not sure if it's a diesel or not, but the cummins in
my tractor does this due to low coolant (caused by a
weeping head gasket - rear left hand corner next to
driver)... the tractor gives heat when the rpms are
up, but at idle there is no heat.

There are quite a few comments online about Dodge pickup heaters. I have a 98 1500 and it works great, but in my 2002 you might as well be sitting on a block of ice. I think my 2002 is going to be different that your 97. But on my 2002 these are the common problems. #1) Broken blend door. The blend door never closes therefore when it is really cold out the outside cold air is always mixing with the air you are trying to heat. My blend door is OK as I can feel a difference between cold and hot when driving down the road with the "vent" turned on and putting ones hand up to the vent outlet while turning the knob from L to R. #2) thermostat - temp gauge was coming up OK anyway, but changed it anyway to no satisfaction. #3) Plugged heater core. Common problem I have been told. Many dissimilar metals in the engine and silicates in the antifreeze block the core tubes. Some indicate that on a hot engine the incoming heater hose should be hot and if the heater core is taking coolant the outgoing heater hose should be warm as well. I took my heater hoses off at the engine and put some Justice Brothers cooling system cleaner in the heater core using a funnel. Was told Justice Brothers was the best. I did get some improvement, but eventually lost heat again. I wonder what running "Iron Out" or some of the calcium/rust cleaners into the heater core would do??? 4) Was at the Dodge dealer yesterday and the service manager said they were also having problems with the temperature control panel. My guess would be the heater core. There are some U-tube videos on cleaning/blowing out heater cores. Fortunately I have other vehicles, but will eventually want mine fixed. The problem is it might take $700 to get to the heater core. On the 2002 I have been told the dash has to come out. Try flushing yours once.

One other thing you could check is the adjusting knob for hot and cold. Check that it isnt cracked and it turns properly. Im sure it is fine but.....

Mine started doing the same thing it is full of
antifreeze . I had a 2000 chevy that would do that
every 2 years. I would have to take coolant lines
off of the heater core and blow backward threw it
then it would work very well. It would be like
orange slime that came out I blamed it on dex cool.
But now I wonder if The green stuff that can be used
in GM or any other kind of vehicle may do the same
thing I am going to check my jugs and see if I got
some of that the last time.

My '96 did that as the heater core was slowly clogging over the years. Try reversing/flipping the input and output hoses to it at the firewall. They are inches apart and not hard to get at. There is no valve at the core to polarize it, so give it a shot and see if it makes a difference by flowing coolant and gunk the other way. Made a huge difference on my '96 that wasn't putting out squat, wouldn't keep my windshield clear as temps really dipped, and had to wear gloves and keep the coat zipped up while driving because it got that cool or cold. That's my "beater" that I drive every day. Raised the temperature output dramatically on mine. Compared to how it was, is now tropical on cold days. If it works, then flush the system to help bend the crud backwards and off, and out.

Good luck.

Mark

When the vehicle is at operating temp, feel both heater hoses. They should both be hot as well. If not suspect heater core blockage or low coolant. If they are hot then it's inside in the phlenum chamber ie. stuck blend door.

Just this evening I was telling my son about the time the heater in my 73 Plymouth Satellite quit putting out heat due to a chunk of silicone plugging the heater's intake fitting. It taught me at a young age to not glob on the 'sillycone'. Just a hint. (wink) Jim

My 2005m1500 heater was crappy and it turned out to be a malfunctioning blend door allowing too much outside cold air.

I had a 1978 Chevy 1/2 ton that wouldn't heat. A contractor had owned it. I found over a hand full of pencils and pens blocking the heater door.
Hal