HVAC issues - Dodge Cummins Diesel Forum
2013-2018 General Discussion General Chit Chat About the 2013 model year differences 6.7L 4th generation Cummins - NO ADVERTISING -

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post #1 of 45 (permalink) Old 01-21-2020, 12:32 PM Thread Starter
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HVAC issues

Anyone else had hvac issues? I’ve got a 2013 Laramie longhorn 2500. AC works great but heat most of the time doesn’t work at all, checked fluids already, changed thermostat and still no improvement. Also when plugged into scanner it won’t pick up the transmission, hvac system and a list of things. But no codes listed other than not being able to read them, nor do I have an engine light on. Could it just be a bad body control module ? Or maybe heater core, blend doors not opening shutting like they should?

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post #2 of 45 (permalink) Old 01-21-2020, 12:44 PM
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It's usually a heater core issue.

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post #3 of 45 (permalink) Old 01-21-2020, 01:07 PM Thread Starter
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I was thinking the same just wasn’t sure with the diagnostic issue as well. The truck can still be running 190 degrees on the coolant and still no warm air but both hoses on the heater core are hot to the touch. I figured if the heater core was plugged only one side would be hot. I can start the truck in the morning and drive down the highway and no heat but I can start it again 20 minutes after I get to work and it’ll blow Luke warm air then later it’ll get a little warmer
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post #4 of 45 (permalink) Old 01-21-2020, 01:12 PM
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Use the heated seats and trade it in when the weather warms up. Sounds like an expensive repair.

2014 White Laramie 2500 CCSB 4x4, 6.7, Keyless go, buckets, Romik steps, Michelin Defender 295-70-18 tires, Snugtop Supersport. Big spoiled Bernese Mtn dog in the back seat. Wind River 250RDSW bumper pull TT (31ft, 7K LBS.) 2003 2500 4x4 5.9 best ever, SOLD.
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post #5 of 45 (permalink) Old 01-21-2020, 01:17 PM
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Both hoses will get hot if you drive it long enough from just convection. Check hose temp early like when it hits 150. Use an infrared heat gun.

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post #6 of 45 (permalink) Old 01-21-2020, 01:37 PM
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Quote:
Originally Posted by wdiesel View Post
I was thinking the same just wasnít sure with the diagnostic issue as well. The truck can still be running 190 degrees on the coolant and still no warm air but both hoses on the heater core are hot to the touch. I figured if the heater core was plugged only one side would be hot. I can start the truck in the morning and drive down the highway and no heat but I can start it again 20 minutes after I get to work and itíll blow Luke warm air then later itíll get a little warmer
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Originally Posted by tsconver View Post
Both hoses will get hot if you drive it long enough from just convection. Check hose temp early like when it hits 150. Use an infrared heat gun.
If you have the heater on hot and blower turned up, one hose should be noticeably cooler. If there's no flow, or not flowing through the whole core, both hoses can be hot as tsconver said.

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post #7 of 45 (permalink) Old 01-21-2020, 01:38 PM
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Basic scan tools will only read basic codes, no abs or body codes, so that's most likely the deal there.

Now, since your A/C still works properly, the blend doors are apparently working, so it is most likely a blocked heater core.

And, yes, both hoses will get plenty warm even though the flow is stopped, the heat migrates up the return hose.

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post #8 of 45 (permalink) Old 01-21-2020, 01:45 PM
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Originally Posted by Ltngdrvr View Post
Basic scan tools will only read basic codes, no abs or body codes, so that's most likely the deal there.

Now, since your A/C still works properly, the blend doors are apparently working, so it is most likely a blocked heater core.

And, yes, both hoses will get plenty warm even though the flow is stopped, the heat migrates up the return hose.
Could it be from mixing the two incompatible antifreeze types??

ETA:

If so, then -- https://www.wikihow.com/Flush-a-Heater-Core

And a tool to help --



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post #9 of 45 (permalink) Old 01-21-2020, 05:12 PM Thread Starter
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I have used the basic scanner but have also used the diesel laptop at my work that we use on heavy equipment and freight liners and Mack’s. We use the same one on all of our diesel trucks to and it. Shows that it cannot read half of the system on the truck but yet no engine light on and not throwing any abnormal codes other than the stuff it says it cannot read which leads to me think it’s a bad body control module
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post #10 of 45 (permalink) Old 01-21-2020, 05:15 PM
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I would try a good back flush on the heater core to see what comes out, if anything.

2014 White Laramie 2500 CCSB 4x4, 6.7, Keyless go, buckets, Romik steps, Michelin Defender 295-70-18 tires, Snugtop Supersport. Big spoiled Bernese Mtn dog in the back seat. Wind River 250RDSW bumper pull TT (31ft, 7K LBS.) 2003 2500 4x4 5.9 best ever, SOLD.
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post #11 of 45 (permalink) Old 01-21-2020, 05:15 PM Thread Starter
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I drove the truck around for about 30 minutes earlier and then parked it and let it idle for about 15 min and got back in and it was blowing the hottest air it ever has and coolant temp showed high 190s to 200 then drove it around and it’s cooled back down as the coolant temp has cooled back to 190
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post #12 of 45 (permalink) Old 01-21-2020, 05:17 PM Thread Starter
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Originally Posted by Highway 4x4 View Post
I would try a good back flush on the heater core to see what comes out, if anything.

I’ll definitely give it a try! Been a pain with this cold weather on only having heated seats and most of the heat I’ve gotten is just by turning it to recirculate which does no good if you are only in the truck for 10-15 min
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