All of a sudden no heat

Hey guys 2014 outdoorsmen 6.4 hemi 2500, I had heat the day before I came out to go to work and started the truck to warm up. I noticed going down the interstate that the defrost was on but was blowing cool air , changed to the feet same result. 30 min drive coolant temp 195 no heat. I took it to the shop , heater hoses not hot just kinda warm, coolant level good. 1st - added some coolant no change. 2nd - checked behind glovebox everything appears to be moving and blowing 3rd - replaced thermostat, still no heat 4th- coolant flush and back flow heater core , no heat . Heater core doing its job. 5th- diagnostics checked nothing , no codes . No heat . Local shop says they can’t figure it out maybe I should go to dealer. Trying to avoid that - any suggestions?

It's probably your heater core, extremely common. Did they use air assist to flush it or just water? Flushing has about a 50/50 chance of fixing it, the other 50% require replacement. You have all the symptoms.

.

buddy just had to have his heater core replaced in his '14 2500 6.7 for a similar reason. From reading on this forum, as mentioned it's a 50/50 shot back flushing the heater core works.

Firtamr said:

Heater core doing its job.

Click to expand...

If the heater core was doing its job you'd be getting heat. The fact that you don't feel any heat tells me one of two things. Either the heater core is not allowing sufficient coolant to flow through it, or the diverter inside the heater box isn't working properly to allow air flow through the heater core. You can test coolant flow through the heater core by feeling both heater hoses, with the engine fully warmed up and heater controls to max heat. If coolant is flowing through them the hoses will feel warm or hot. If not, they will be cool to the touch.

mikeru said:

If the heater core was doing its job you'd be getting heat. The fact that you don't feel any heat tells me one of two things. Either the heater core is not allowing sufficient coolant to flow through it, or the diverter inside the heater box isn't working properly to allow air flow through the heater core. You can test coolant flow through the heater core by feeling both heater hoses, with the engine fully warmed up and heater controls to max heat. If coolant is flowing through them the hoses will feel warm or hot. If not, they will be cool to the touch.

Click to expand...

Unfortunately feeling the hoses is not always a tell tale sign. Both of mine were warm/hot and it was still a heater core issue. It was either enough flow where the hoses felt hot but not enough to really warm the cab or it some how gets back fed from the other side if the flow is low making the hose feel hot on both side?

It's rare to see a 4th gen with diverter issues (pretty common on the 3rd gens), it's almost always the heater core.

.

Firtamr said:

Hey guys 2014 outdoorsmen 6.4 hemi 2500, I had heat the day before I came out to go to work and started the truck to warm up. I noticed going down the interstate that the defrost was on but was blowing cool air , changed to the feet same result. 30 min drive coolant temp 195 no heat. I took it to the shop , heater hoses not hot just kinda warm, coolant level good. 1st - added some coolant no change. 2nd - checked behind glovebox everything appears to be moving and blowing 3rd - replaced thermostat, still no heat 4th- coolant flush and back flow heater core , no heat . Heater core doing its job. 5th- diagnostics checked nothing , no codes . No heat . Local shop says they can’t figure it out maybe I should go to dealer. Trying to avoid that - any suggestions?

Click to expand...

I feel your pain. I am on my 3rd heater core. 3100.00 bucks into them. They are going to eat the third one. Two plugged within 3 months. They said they keep plugging up with casting sand from the block. I would think if they are having problems all over the country with sand there would of been a notification or bulletin out. I didn't receive one. Changed 3 thermostats myself thinking that was the problem. I found that when I hooked up clear hoses to the inlet and outlet of the heater core, I had minimum flow threw it after I flushed it. Rev up the motor in order to get good flow. Out driving around you can backoff the accelerator and seems to go cold. One other one is that you turn the corner fast it goes cold for a short. Both hoses are hot when feeling them. Not sure but with the sand going thru the water pump if anything can effect the flow. That is on my list if all else fails. Gotta get some heat when its -20 out. 2014 hemi 2500, 6.4 L

I feel your pain. I am on my 3rd heater core. 3100.00 bucks into them. They are going to eat the third one. Two plugged within 3 months. They said they keep plugging up with casting sand from the block. I would think if they are having problems all over the country with sand there would of been a notification or bulletin out. I didn't receive one. Changed 3 thermostats myself thinking that was the problem. I found that when I hooked up clear hoses to the inlet and outlet of the heater core, I had minimum flow threw it after I flushed it. Rev up the motor in order to get good flow. Out driving around you can backoff the accelerator and seems to go cold. One other one is that you turn the corner fast it goes cold for a short. Both hoses are hot when feeling them. Not sure but with the sand going thru the water pump if anything can effect the flow. That is on my list if all else fails. Gotta get some heat when its -20 out. 2014 hemi 2500, 6.4 L

Sorry to hear this, i just don't believe anything about casting sand

I think more likely someone mixed HOAT & OAT

If they do believe there is casting sand in the engine,
Why wouldn't they pull the radiator & take it to a real radiator shop, not a auto parts store. Then they would disassemble the radiator & see all of this so called sand in the tanks.

When the shop ran the diagnostics, did they bypass the manual controls ? The ones not on the radio screen ?

Those controls switches can go bad

You mentioned that someone pulled the whole HVAC unit from under the dash, did they replace any of the doors ?

If you decide to do that again, personally i would replace all the doors with doors & great doors by
Blend Door USA, they are made of light weight aluminum.

The Mopar Actuators are the best brand out there, but their doors are crap & the Dorman Doors are not too much better

Blend door or heater core, either way dash has to come out, that's a decent job and expensive if you don't diy, it's all labor costs, 10.8hrs book time iirc.

mtnrider said:

Unfortunately feeling the hoses is not always a tell tale sign. Both of mine were warm/hot and it was still a heater core issue. It was either enough flow where the hoses felt hot but not enough to really warm the cab or it some how gets back fed from the other side if the flow is low making the hose feel hot on both side?

It's rare to see a 4th gen with diverter issues (pretty common on the 3rd gens), it's almost always the heater core.

.

Click to expand...

Yea, that hose test is usually showing problems just in the engine bay, not the interior side, as you said.

Reset the blend door

One other thing
Hot air does not come out of the defroster vents, only cold air does
Can you imaging what blowing hot air directly on a frozen windshield would do
..........................................................................

Most HVAC boxes have 4 actuators
#1 actuator is directly behind the glove compartment
it is a Fresh Air Open/Close door control

#2 actuator is near the HVAC Fan, ( right where the passengers left foot would normally be ), look just left of the Fan Motor Housing, you will notice #2 actuator
It controls whether the air is directed to go through the Heater Core or through the condenser
(as you work the controls, you can watch the actuator arm move as that door moves. )

watch this


replace control head


One HVAC Box model & how it works