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Much colder here, I have to put it in recirculating mode to get quicker heat. I have run it with the fan removed because I don’t tow much. At 23F you should be able to have some heat if you remote start it AND remember to leave it in recirculating mode. I have to cycle mine back and forth between defrost to clear the windows and recirculating to speed the heat up. Once warmed up to 180+ it should keep you warm unless you start getting to -20 or

Last year I forced the recirculating door to stay about half open in all positions and fully open in recirculating mode. At about half open the windows stay clear. Fully open they fog up inside pretty quickly. I would like to find a cable to independently control the fresh air/recirculating flap.

Blocking the radiator helps.

Flushing your heater core may help.

The openings for the two coolant pipes in the dash is another spot the seal can be nonexistent.
 

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1994 Dodge Ram 2500 2wd auto IFS
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Discussion Starter · #22 ·
What is aggravating is that in order to get my defrost to work I have to cycle the switch from vents to defrost for the defrost to fully open up. Idk. Something is wrong with the vacuum or the switch. Been looking into that for a while. But after I cycle it everything works normal. I do believe that not having vapor barrier and good insulation could be a root cause in not heating up the inside correctly. Dang hands were freezing the other morning. Haha. If it ain't raining tomorrow I'll see what all needs to be done. I don't drive it much because I'm about to swap the transmission out but it's my backup right now but still needs to have good heat going into winter.

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Another potential reason for poor heat is a cheap aftermarket heater core. The age these trucks are it’s more then likely it’s been replaced at some point. The aftermarket aluminum heater cores just make poor heat.

Factory ones can be had from genos garage for a good price, if you open the hvac box it’s a good idea to replace the heater core while you’re in there.
 

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If temp is reading about 190 on dash either the blend door is not operating correctly and directing the air through the heater instead of the ac unit or the heater core is clogged with gunk.
 

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I would check the blend door. Mine wasn’t working with the switch on the dash. If you look under the dash on the passenger side, there’s a little silver “stud” towards the left side. Stick a pair of vice grips on it and spin in manually while the truck is warmed up. Put a hand infront of the vent while you turn it and see if you get any hot air.
 
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#1 , idling produces very little heat in a diesel . It take work to make heat in this engine.
OP never mentioned the heater core . Please forgive me if i missed it.
Please measure the output heat from a vent . With a good OEM brass n copper HC and a good thermostat at OT you should be able to get real 150*F heat / air . To ME it sounds like you have an old heater core and are getting the old 101* "heat " . We have all been there and its marginal at best. Remember the HC seems to be the filter for the cooling system ... most of the crud gets in there and stays .
Take a temp gun and shoot the heater core hoses .......... If they are about the same temp , its clogged .
My 94 bomber puts out hot heat 150-155*F, and has a 190* stat . I always have to adjust it down . GRANTED , it takes 5 min idle and a solid 10-15m mild drive to achieve operating temp ( 190-195 F+- in my case ) , but even before OT its putting out some cab heat.
I have had clogged HC 101* heat before ,, and its miserable / doesn't cut the mustard .

** Checking the blend door is also a great idea , as mentioned above .
 

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If the blower isn't switching between face/feet/defrost, then you definitely have a vacuum leak.
 

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While I'm waiting for parts for the transmission swap, I drove my truck the other day. 23 degrees outside. I used auto start to warm the truck up. About 15 mins or so of idle time. I get out to the truck and it's really not much warmer. Truck has a brand new radiator, thermostat and water pump. I know plugging it in will warm up faster but honestly it's not that cold yet.
When driving on the highway, the truck feels warm at the vents but it doesn't really ever get "warm" in the truck. Definitely warmer inside than outside tho.
Is there anything that can be done to get more of a hotter heat within the cab? I will say I do plan on covering the grille but unsure how much to cover.
Also the vapor barriers in both doors have been removed for some time now due to other owners of the truck. Never had it when I bought it. I do plan on doing something about that temporarily this year.
Any other advice? Tennessee usually isn't too cold but it's still got a pretty good chill inside the truck even after 20mins of highway driving. It usually doesn't get a really good comfortable temperature till about 5-10 from work. Oh and can someone show me how to add a signature (Tapatalk user).

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Get some shutters. They work real good on warm up.
 

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Idling doesn't generate too much heat, and I wouldn't expect it to get real toasty for a while, but 15 minutes should probably do it unless it's so cold out it's losing more heat through the oil pan than it's generating. Best to just get moving. Blocking the grille won't do much either unless your thermostat or coolant bypass aren't working correctly, which may be the case. There shouldn't be any coolant flow through the radiator until the thermostat comes up to temp. If the temp gauge looks like the engine is up to temp, but you're still not getting much hot air out the vents, your heater core may be clogged up, which isn't terribly unlikely in a 20+ year old truck. Definitely some threads around about cleaning it out. Lastly, using the recirc setting can help get hotter air, but of course then you can't use defrost or anything. I think some folks in cold climates have propped the recirc door open so they can use the defrost/footwell settings.
I put a little ceramic heater in my cab when I'm not using it with the window just cracked .. warm and no fogging.
So my recirculating door works which is good. However when I use it, all my windows get humid foggy unfortunately. I'm pretty sure coolant does as it should however I haven't researched enough on the coolant bypass, so yeah there's that haha. The great feels a little bit less than hot at the vents. I'd say about normal. Now that I'm writing this, my vents don't blow strongly. Even when moving the recirc door. Prolly will pull the blower motor out to check it and make sure it's not gotten debris in it. I just hate to do anything with the dash and bezel piece cause like everyone's truck, it's brittle and no one makes them. Stupid caps and stuff like that but nothing that looks great and trash. Hopefully more people will get into this conversation. Would love to hear how the northern guys keep there trucks warm inside.

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Put a little ceramic heater in cab at night
 

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Any links to said heater?
i have a remote starter on mine. also have the 3 cyllinder idle and auto high idle when cold. i have a 1200W electric heater in the cab along with the factory radiator heat. so on RS if below 30F the electric heater powers at 600W and high idle kicks on. if under 15F the 3 cyllinder kicks on and the electric heater runs at full 1200W. if engine temp reaches 100F and RS is still active the blower motor will power on and then shuts off for manual control upon remote start shut down.
i also have my wiper motor wired to aux on the remote start so it will activate from my remote or phone if i want to clear snow with out having to go outside.
the defrost auto triggers with remote start under 35F as well.
 

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I'm just using a $15 heater from Menards, and a couple relays
 
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