Low heat in truck

[Rez9805]

It's cold out know, like -40ish cold. Needless to say I have very little cab heat. Coolant temp is at 190 winter front is on truck, both lines on my heater core are hot, fan is pushing lots of air out the vents, deff, or floor heat, I can change the heater control and make the heater colder. Even when my Espar is on I still do not have hot air in the cab. If my heater core was not working properly would I still be able to pass fluid through it?If I can change the heat controls from hot to cold, my blending door should be working?If I have good flow of air out my vents, deff, and floor heat my a/c and heater core should not be plugged?If my heater core is returning hot coolant back to the motor and the fan is blowing why don't I have heat?any help would be greatly appreciated.thanks

[scummins]

I have the same issue my uncle said they used to reverse the lines on the heater cores to free up any debris. And then reverse them back after running it to full temp. I haven't tried it, but I also figure thts the same as a coolant flush. :-\ Sent from my RM-820_nam_att_100 using Tapatalk

[Rez9805]

Tried that already, back flushed it, ran CLR through it, flushed it with pressured air. I can flow coolant through it no problem, that's why I don't think it's pluged. I appreciate the help though, I'll take any ideas right about now

[dripley]

Most likely you have a blend door problem. The motor that operates it has a plastic fitting that ties them together and they can crack throwing the door off. Give a look at this http://www.heatertreater.net/index.html.

[Mopar1973Man]

Like I know being I just checked mine last night from the Fire Meeting. In the 2002 Dodge Cummins I got 193*F worth of coolant on a 12*F night and the temperature coming out the dash was 135-140*F depending on fan speed. Now if both heater hoses are hot then the heater core is plugged up and not exchanging heat. Just like a plugged up radiator both hoses will be hot because of a lack of heat exchange. Just because fluid flows through it doesn't mean its good. Just like a plugged radiator will still flow coolant too but most of the tube don't so the heat exchanging effect is poor hence why a truck will over heat. Same with my truck not both hoses are hot. One is hot the other is cooler because of good heat exchanging from the heater core. Both hoses hot = Plugged heat core.One hose hot and the other cooler = Good heater core exchanging heat with cold air.

[dripley]

Like I know being I just checked mine last night from the Fire Meeting. In the 2002 Dodge Cummins I got 193*F worth of coolant on a 12*F night and the temperature coming out the dash was 135-140*F depending on fan speed. Now if both heater hoses are hot then the heater core is plugged up and not exchanging heat. Just like a plugged up radiator both hoses will be hot because of a lack of heat exchange. Just because fluid flows through it doesn't mean its good. Just like a plugged radiator will still flow coolant too but most of the tube don't so the heat exchanging effect is poor hence why a truck will over heat. Same with my truck not both hoses are hot. One is hot the other is cooler because of good heat exchanging from the heater core. Both hoses hot = Plugged heat core. One hose hot and the other cooler = Good heater core exchanging heat with cold air.

I agree with you on the both hoses hot equals bad heat transfer, but I have seen so many posts stating that they should both be hot to be working right. I just cant get my arms around that theory.

[MnTom]

I agree with you on the both hoses hot equals bad heat transfer, but I have seen so many posts stating that they should both be hot to be working right. I just cant get my arms around that theory.

What you need to keep in mind Dave is that to most of us 120* is pretty warm. If you have 190* water going in and 150* water coming out they both will feel hot even though there is a 40* TD.

[dripley]

I realize that, 190 in and 150 out are both going to burn. 120 I can hold with no problem. But from what I believe I read folks were saying they ought to be equal in temp to be working right. Maybe I just misunderstood what they were trying to say.

[Rez9805]

Thanks a bunch everybody, changed my heater core and it is working much better, install went really good followed directions i found on here.Ps. my wife thanks you all aswell, she is finally warm.

[dripley]

good to hear. Being warm is much better.

[Mopar1973Man]

Created a write rather late but here it is... http://forum.mopar1973man.com/threads/8814-Heater-Core-Performance

Well Gang. I've been seen these goofy threads about people trying to figure out if a heater core is functional or plugged up. So since I took my truck to town for a job I figure I do the bench testing for the heater core to let you know what a good functional heater core will do. So measuring the vent temperature from the center vents with Bi-Level setting I measured... Fan Lo - 160*F roughly Fan Hi - 150*F roughly Outside temperature - +10*F Engine Coolant Temperature - 193-195*F As for the heater hoses they should not both be equally hot. I checked mine after driving about 6 miles from town stopped at a rest area and left the blower on Hi and felt both hoses. The hose from the head is very hot and you can only hold it for a short period before the heat burns your hand. As for the other hose that routes under the turbo in the steel tube that hose is warm but you can hold on to it for a very long time without even letting go. I see several threads where people say that if both hoses are hot the heater core is functional. This is wrong there should be a exchange of heat/cold with the heater core so one hose should always be cooler which is the return line from the heater core. If both hoses are equally hot then the heater core is not exchanging heat/cold and not flowing optimally. So I figure I'd throw this tidbit out there for everyone and hopefully help others diagnose heater core performance issue.

[dorkweed]

What causes the heat exchanger to stop "exchanging" heat???? Scale from the water used in our trucks coolant??? Plugged passages due to the same????

[Mopar1973Man]

Mostly plugged passages. As for me I can't say its the mineral in the water since I'm using tap water and creek water in my truck and still never had a issue with a cooling system or heater core. I will admit I had to change my heater core because of a cracked tube (vibration / movement damage) not a plugged heater core or rotten heater core. So I really can't base my heater core as a good test bed but the radiator is spotless internally yet.

[Killer223]

how would one clean the heater core the best? with out removing it. does the radiator flush really work., CLR? just maybe one of those preventive maintenance things.

[MnTom]

how would one clean the heater core the best? with out removing it. does the radiator flush really work., CLR? just maybe one of those preventive maintenance things.

Best way is to use water that won't plug it up in the first place. I don't know how you would clean out the inside.

[hex0rz]

A heater core flush may remedy it. But the stuff that they sell now is worthless. Just as strong as a soap! The radiator shops may still have some of the good stuff, but its probably not going to be very common. EPA working hard... :banghead:I would think the easiest way would to take it to a radiator shop. Like I said, they may have the good stuff, and I would imagine they would just unhook both the inlet and outlet line to the heater core and flush it out with the cleaner. The guy I went to here locally can't use the cleaners anymore and he uses REALLY hot steam water with a good flow and pressure. Mine was so plugged up the core bellowed out and almost exploded from the amount of restriction.The best preventative maintenance is to regularly flush your coolant at the service interval. IIRC, use PH paper to determine value and change out if it goes too far from neutral.As well, this is just something I was told by a mechanic my father knows:Given that the vehicle serves as a ground for the electrical system, everything is essentially energized. This even means your coolant has an electrical charge. He said people never take this into account and use distilled water with their coolant. Given that there are no minerals, etc in that water, the process of electrolysis draws the block metal away from the engine and thins the metals out. So he said to use regular tap water with your coolant instead to prevent this.Whether or not that really has much truth to it, I dunno? He was a fleet mechanic for school buses and owns his own auto-repair shop as a home based business.I personally do not understand that reasoning as I would think the charge the vehicle gives the fluid would cause the minerals, etc. to want to be attracted to the metal and therefore cause an accumulation and then create a blockage...

[Mopar1973Man]

The only thing I use distilled water in is my batteries. Never used distilled water in my cooling system on any vehicle including ATV's, motorcycles, etc. The only time I've ever seen mineral build up is when someone starts skipping flushes and allows the electrolysis to oxide the metals. Typically that when the coolant starts to change rusty color from oxidation that starts from a corrosive coolant. (hi or lo pH number)

Given that the vehicle serves as a ground for the electrical system, everything is essentially energized. This even means your coolant has an electrical charge. He said people never take this into account and use distilled water with their coolant. Given that there are no minerals, etc in that water, the process of electrolysis draws the block metal away from the engine and thins the metals out. So he said to use regular tap water with your coolant instead to prevent this.

I actually agree with this. It could be possible...

[hex0rz]

Now, if there was someone here that could really give some surefire input about it!

[Mopar1973Man]

My thought are as long as you cooling system is closed and not leaking then the minerals don't count either. Since I've been using creek water and well water for the cooling system the amount of minerals are measured in PPM in amount. But if you have a leaking system where water is constantly added now you would have the distilling of the mineral on the block as well. Since my truck doesn't leak coolant the block is still clean from what I can see from different openings. As for the electrolysis depending on what you need to do you can either strip metals aways or add metals. same principal about chrome plating or rust removal.Some where on the site is a article about rust removal I think Flagmanruss posted it.