Hello, I have a 2008 Nitro R/T 4.0L V6. A month or so ago, the heat inside the cab slowly vanished and now I have no heat. I've checked my fluid level, good, however a day later the check engine light came on. I have a Engine Coolant something...P2181 I believe. My first thought was the ECT sensor. (the vehicle has 152k on it at this point) I replaced the sensor, code vanished, however still no heat. Double checked the hoses and determined the t-stat was bad. Replaced it and then noticed the return hose from the water pump was ice cold. Replaced water pump and timing belt. All hoses have been replaced. No leaks anywhere, but still no heat and the P2181 code is back. All hoses are hot as should be, except the outlet (return hose) from the heater core.

I read that the 07 4.0L have a bleeder valve and I've familiarized myself with that location and procedure. My model appears to have one as well, but after all repairs, I flushed the coolant at the shop. Could there still be air?

I've taken the dash apart and visually inspected the heater core, blend-air door, and actuators...all which are working perfectly. No blockage or restrictions. I have also verified the blower motor and fan are working properly. Again, everything=ok

At this point I'm suspecting air trapped or a PCM re-flash on the temp module. There was a TSB out on it, but I'm trying to avoid the stealership prices. Anyone else have any ideas what else it could be at this point?

Also have inspected thoroughly the head gasket, headers, etc. Everything = ok
Heater core is not clogged either. I have flushed it twice (once from the inlet hose to the outlet hose, then reverse from outlet to inlet) Ample amount of fluid movement.

 

Update:

Last night on my way home I took advice from another DF member and went 0-60 a few times to help push air out. Heat improved, tons of DTC's were set.
Today at work I checked them and realized I forgot to run the Cam-Crank re-learn procedure with the scan tool. That cleared all codes.

What I thought was a bleeder valve was indeed one and heat became even better.
For sake of having the scanner already hooked up, I double checked the HVAC system once again.

This time 2 codes were set.....I guess Mopar PCM Engineers made it where the priority codes are set (even though nothing is pending) before low priority becomes set.

My codes are a B1045 and B10A7

The codes represent Mode Panel 1 Travel Distance Too Far and Left Blend Door Travel Too Far....something like that....

Diagnosis/Repair is simple.....Take actuators off and try to rotate the gear, any movement, replace....I've already done that and there was no movement so the next step is to check the door itself for worn, warped, broken, etc gears.....if broke, replace, if not, the actuators are bad.....

Depending on price and how much I've already invested, I'll probably just go ahead and replace both actuators and door(s) because it's a matter of time I'm sure before the actuators do go.....Of course, after diagnosing.

At this point; with the flooring the car and using the bleeder valve, the heat has drastically improved, but due to the blend air door issue, only one side puts out (passenger side). New update once I "throw" those parts at it.

In the long run, all my parts were causing issues. Unfortunetly, they all decided to surfice at one time. Good thing I know some parts dealers or I'd be hurting. All together, doing labor myself, parts ran me 140 for the t-stat, water pump, timing belt, and engine coolant temp sensor. Another 40 bucks for spark plugs (not part of the issue, but the manifold was off so I might was well while I was at it NGK), and I haven't received quotes for the blend air door/actuator yet.

 

Well, after setting the Nitro to the side, I had time to think of what could still be causing my issue. I ruled out what it couldn't be at this point and all that was left was electrical.

I first pulled the center console off and checked to ensure I had voltage coming into pin connectors 5 and 6. After this, I checked the internal resistance between those same two connectors. It was above 5 ohms so there were no shorts there. Next, and last step, I unplugged at the totally intergrated power module (fuse box in the engine compartment) and checked the resistance between pin connectors 26 and 27 in relation to pin connectors at the dash of the same connector above of 5 and 6. The resistance in ohms on both were less than 5 meaning no issues with the wiring, so therefore, my issue lies within the circuit board where the ***** for heat/cold, zone (mode) control, and speed of the fan are all attached to. I replaced this, recalibrated the module, and boom, my issue is offically fixed.

 

How did you recalibrate the module?