Engine/Transmission (1994 - 1998) long time to get heat to cab, what gives?

[Bandit1]

for a while now it takes a long time to get heat to the cab. i have changed out the thermostat 3 times and checked for any blockage, vents work fine, blower motor runs fine, engine temp stays right around 180, no leaks inside cab or outside, not loosing any coolant, coolant is full. what gives? i am not sure what is goign on, it takes close to 1 hr for me to get decent heat in the cab and the GF doesnt like the cold to much. last winter i would plow snow for a few hrs b4 i would get hot air out of the heater vents. any ideas is greatly appreciated. thanks in advance, josh

 

[Gene Arnold]

Bad heater hose? (collapsed, filled with crud, etc. )



Kink in a hose?



Clogged heater core?

 

[PRattenbury]

Control valve working properly?

 

[Bandit1]

after doing some more extensive searching on this site there are a few things i am going to check again this week. control door working propler, evidence of mice, proper coolant flow to heater core. please keep the ideas coming, i really dont want to have to pull the dash until i know that is the culprit. thanks jsoh

 

[Grizzly]

for a while now it takes a long time to get heat to the cab. i have changed out the thermostat 3 times and checked for any blockage, vents work fine, blower motor runs fine, engine temp stays right around 180, no leaks inside cab or outside, not loosing any coolant, coolant is full. what gives? i am not sure what is goign on, it takes close to 1 hr for me to get decent heat in the cab and the GF doesnt like the cold to much. last winter i would plow snow for a few hrs b4 i would get hot air out of the heater vents. any ideas is greatly appreciated. thanks in advance, josh

I'd start with Advanced Diesel Technology. Maybe they screwed something up in whatever they did to the engine.

 

[vssman]

When I changed my T-stat, I had a heck of a time getting all of the air out of the heater hose. I ended up installing a coolant flushing tee and topped off the coolant with that tee open.

 

[hsmith]

No control valve on these, but there is a blend door that can break. Also check the servos.

 

[PRattenbury]

So coolant is allowed to pass through the heater core at all times? That's unusual. Why wouldn't you get heat when the AC gets used in the summer? Are there 2 fans and 2 separate air ducting systems?

 

[BigPapa]

Why wouldn't you get heat when the AC gets used in the summer?

Blend door. It doesn't allow air to flow through the heater core. I can't think of anything I've owned in the past having a "valve" to redirect coolant around the heater core.



Scott

 

[PRattenbury]

Have you seen valves used to stop the flow of coolant to the core? I must be old. That's the way it used to be done. Either cable- or vacuum- actuation.

 

[2broke2smoke]

if the temp is staying at 180 i'd try a 195 thermo ... that's factory

 

[JWilkinson]

heat

My overflow valve was bad. Once I replaced it I had plenty of heat. It is not the heater, you need fuel is my bet.

 

[tony597fitter]

Do you have a Cummins OE stat in your truck, or some cheapo from the auto parts store?

My truck wouldnt get heat either after I changed my stat to a cheapo brand.

I did everything I could think of afterwards to try and fix it. Blend door, flush heater core, new jiggler valve, bled air, and so on.

I went to Cummins to pick up some parts and while I was there I picked up a Cummins stat and wouldnt you know it.

HEAT after I installed it.

 

[MMcCallie]

Haven't done much work on Dodge trucks but everytime my Ford has had HVAC issues it's come down to vacuum issues. I'm running an updated Cummins thermostat which my Auto Zone engine coolant temperature gauge says opens at 180 degrees. With my heater running a while, the thermometer in my dash vent has read up to 150 degrees F a few times this season.

If your engine is 180 there is nothing wrong with the engine. I assume your DTT is an automatic transmission. Does that mean you have a transmission oil/coolant heat exchanger mounted to the passenger side of your engine, beneath the turbo? I've heard they are prone to leaking. Perhaps your coolant is being misrouted in some such way.

You might get an infrared thermal measuring gun and point it at different locations where there should be heat to help diagnose. On my Ford, i have installed a kit that directs coolant away from the heater core when Max A/C is selected for cooler A/C. I imagine you will find just one simple part needing to replaced that will allow heat to flow into your cab. Search through some diagrams at your local parts store.

 

[hsmith]

Only blend doors on these, not like the GM's that use a valve to block water flow. With engine up to temp, both heater hoses should be hot. If the return is not as hot as the feed, there is a restriction in the core. If both are hot, then you will need to work under the dash probably. Temp gun is a wonderful tool for these problems.

 

[hammersley]

Only blend doors on these, not like the GM's that use a valve to block water flow. With engine up to temp, both heater hoses should be hot. If the return is not as hot as the feed, there is a restriction in the core. If both are hot, then you will need to work under the dash probably. Temp gun is a wonderful tool for these problems.

If you've not replaced the heater hoses - CUT the ones you have off and use these - I think they're the same for the 12 valve... ... . but if not NAPA has ones that will work at a FRACTION of the cost from Dodge. .



https://www.turbodieselregister.com...002/189476-heater-hoses-wrong-parts-book.html



NOW with the hoses removed you can check the flow through the heater core - attach a hose and see if there is a full flow..... you can also see if you're getting any flow from the heater outlet to the core... ... .

 

[GAmes]

Also drop the fan motor (three bolts on the pax side plus a wire connector) and feel up there for leaves, grass, etc. If it is real dirty a partial fix is spraying a cleaner thru the core. Most of it will drain from the A/C drain line, and you can wet-vac the rest or soak it up with shop towels.

 

[SRath]

"When I changed my T-stat, I had a heck of a time getting all of the air out of the heater hose. I ended up installing a coolant flushing tee and topped off the coolant with that tee open. "



Just a warning: Unless you were able to find a metal tee, you will want to keep a very close eye on that plastic one. I used the same thing on mine to aid in backflushing the cooling system and happened to notice a couple of orange stains on my exhaust elbow after thoroughly washing my motor a couple years later.



I barely touched the cap on the tee to ensure it was tight (orange had to be coolant and it was directly overhead), and the whole thing crumbled in my fingers. I was extremely lucky to find that when I did. I removed the tee and installed a metal splice. The plastic just doesn't hold up.

 

[vssman]

Thanks for the tip on the tee...

 

[Desperado]

for a while now it takes a long time to get heat to the cab. i have changed out the thermostat 3 times and checked for any blockage, vents work fine, blower motor runs fine, engine temp stays right around 180, no leaks inside cab or outside, not loosing any coolant, coolant is full. what gives? i am not sure what is goign on, it takes close to 1 hr for me to get decent heat in the cab and the GF doesnt like the cold to much. last winter i would plow snow for a few hrs b4 i would get hot air out of the heater vents. any ideas is greatly appreciated. thanks in advance, josh

I had the same problem, what I did to fix it was, take the hoses off of the feed and return tudes (over the manifold) hook up a small 12v pump to the hose closest to the valve cover, put an inline filter on the other hose, have a bucket you can pull from and return to, then mix some aluminum cleaning acid and water in the bucket, with the 12v pump you can now run the acid through the heater core back flushing it, I did this for around 1hr, then run clean water through teh heater core to remove the acid, hook the heater back up, refill the antifreeze, you should now have good heat in just a few minutes after starting the rig, I checked the before (130* at the heater vents) and after (170* at the same heater vent) results with an infrared thermometer, I now have heat and I'am happy again.