2013 RamTruck 3500 Dually No Heat in Auto

[gdmercad]

No heat when AC is in auto on Dual Climate Control. When control button for upper vents is pushed, air flow is directed to upper vents with no heat until AC button is depressed to the off position. Took it in to dealership and they diagnosed the system and provided me with the results, which was only a actuation test. All actuation passed. I told them that heat will be produced when the system is taken out of auto and the ac button depressed to off. They responded that it was a clogged heater core and it needed to be replaced at a cost over $2000.00. I paid them for the diagnostics $138.00 and left unimpressed. I went back home and took reading on the heater core hose inlet and outlet under the hood and got 167 on the inlet and 150 on the outlet using an infrared temp gun. The engine coolant temp was 170 according to the dash gage. I ran the system with auto and ac off and got air temp approx 110. When switch to auto and thermostat set to Max Hi, the temp rapidly dropped. I am thinking something in the control system is causing this and was wondering how to check the components associated with temp control

 

[GTyankee]

So the dealer was mistaken about the HVAC Heater ?
You said that you had 110 in the interior of the cab ?

If you have sufficient heat in the cab, your control knobs may be your issue

OR maybe A/C is for cold air & not meant to be on when you want heat

 

[gdmercad]

So the dealer was mistaken about the HVAC Heater ?
You said that you had 110 in the interior of the cab ?

If you have sufficient heat in the cab, your control knobs may be your issue

OR maybe A/C is for cold air & not meant to be on when you want heat

The air exiting the vent was 110 deg f, the cab was 80. When placed in auto, the temp dropped significantly. The outside temp was approx 50 deg f. I called the dealership and the service manager was adamant that the heater core was blocked. I expressed to him that I was getting good heat when it was in manual, but no heat when placed in auto. He told me that when they scanned the system there were no coded indicating a faulty component, so it had to be the heater core. I asked him if the scan included the ac/heater control module and he stated it was a one stop shop scanner that checked everything and if the control module was faulty it would of thrown a code. I am feeling it may be in the control system, controller maybe but do not know how to check it short of replacing it.

 

[GTyankee]

There are a few Youtube videos on the HVAC System
Look for videos made by Motorcity Mechanic

 

[turkeybird56]

The air exiting the vent was 110 deg f, the cab was 80. When placed in auto, the temp dropped significantly. The outside temp was approx 50 deg f. I called the dealership and the service manager was adamant that the heater core was blocked. I expressed to him that I was getting good heat when it was in manual, but no heat when placed in auto. He told me that when they scanned the system there were no coded indicating a faulty component, so it had to be the heater core. I asked him if the scan included the ac/heater control module and he stated it was a one stop shop scanner that checked everything and if the control module was faulty it would of thrown a code. I am feeling it may be in the control system, controller maybe but do not know how to check it short of replacing it.

Prime example of mechanics are no longer mechanics, they cannot troubleshoot a problem. They read all their codes and go by their flow chart. They are Technicians now. Reminds me of going to a Military TMC with a problem, and there is the med tech asking you questions and going by a pre-printed flow chart.

 

[gdmercad]

Prime example of mechanics are no longer mechanics, they cannot troubleshoot a problem. They read all their codes and go by their flow chart. They are Technicians now. Reminds me of going to a Military TMC with a problem, and there is the med tech asking you questions and going by a pre-printed flow chart.

Hey there turkeybird56. Retired Navy here. Your on point with your reply to my post.

 

[indept]

So at most you have a partially blocked heater core if their diagnosis is correct. Did the option of flushing the heater core come up?

 

[crash68]

The engine coolant temp was 170 according to the dash gage. I ran the system with auto and ac off and got air temp approx 110. When switch to auto and thermostat set to Max Hi, the temp rapidly dropped.

The air exiting the vent was 110 deg f, the cab was 80. When placed in auto, the temp dropped significantly. The outside temp was approx 50 deg f.

So if I read this correctly, the coolant is 170°F and the outside temperature is approx 50°F. I sorta agree with the dealer, the heater core is only raising the air temperature 60° with 170°F coolant and the temperature loss on the water side of the heater core is 20°F. A partial blockage would cause the low delta on the air side.
There's been a several people on this reporting low or no heat from the Gen4 HD trucks around the time Ram switched to OAT coolant which was '13 model year. Find an independent mechanic to change the heater core, if I remember correctly my buddy paid $900 to have his changed in his '14 2500.

 

[gdmercad]

So at most you have a partially blocked heater core if their diagnosis is correct. Did the option of flushing the heater core come up?

no, just a quote to replace @$2k+

 

[gdmercad]

So at most you have a partially blocked heater core if their diagnosis is correct. Did the option of flushing the heater core come up?

No, just a quote for replacement @$2k+

 

[gdmercad]

So if I read this correctly, the coolant is 170°F and the outside temperature is approx 50°F. I sorta agree with the dealer, the heater core is only raising the air temperature 60° with 170°F coolant and the temperature loss on the water side of the heater core is 20°F. A partial blockage would cause the low delta on the air side.
There's been a several people on this reporting low or no heat from the Gen4 HD trucks around the time Ram switched to OAT coolant which was '13 model year. Find an independent mechanic to change the heater core, if I remember correctly my buddy paid $900 to have his changed in his '14 2500.

Most likely back flush core and if no/little improvement, will check into an independent mechanic, once I return to Virginia. Currently rving where the weather is much warmer than home.

 

[gdmercad]

Would the ac/heater control module cause this???

 

[indept]

Most likely back flush core and if no/little improvement, will check into an independent mechanic, once I return to Virginia. Currently rving where the weather is much warmer than home.

Hopefully that will fix it. Should be a lot less than $2k.

 

[mtnrider]

Yep, Clogged heater core is a common failure and most likly your issue. Been there done that. Flushing helped mine (air assisted back washing) but it's still not perfect. You have a 50/50 shot if flushing will help but it's worth a try.

Reference the video below for the proper way to do it..

Flushing A Heater Core

Come along with Eric O. at the SMA shop as we diagnose and repair this 2013 Ram 3500 Cummins that came in with a complaint of no heat out of the dash vents. ...

www.youtube.com

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