23 Trail Boss w/3.0l Duramax - Cabin heat issue

[Haufski762]

Gents,

 

I took my 23 Trail boss on a drive yesterday and on the way up to our destination I had the heat set at 74 and on auto. It would blow between cold and warm air but it was tolerable. If I increased it to a higher number, it seemed to warm up but never seemed to stay steady. Hot and cold. Today on our way back, I had it on High and auto but I was getting lukewarm air out of the system. The engine temp was normal. External temps were around -20 on both days. 

 

Any ideas on why? I looked for winterfronts but I can't seem to find any for the 1500's. 

[calgator73]

Provided your engine temperature was anywhere close to normal your problem likely isn't an inability of your engine to develop heat.  You might have a problem with the temperature sensor used by the vehicle to determine either your inside temperature or your outside temperature (I believe there's a separate one from the one that displays on your infotainment system).

 

To test this theory manually crank the heat up for all zones to the maximum it will go and crank your fan speed to the maximum.  If it puts out tons of heat then your problem is most likely in the sensors.  

 

Also verify your coolant reservoir is full.  If somehow you get air into your heater core and it will not release that can also affect your performance

Edited January 14, 2024 by calgator73

[Haufski762]

"To test this theory manually crank the heat up for all zones to the maximum it will go and crank your fan speed to the maximum.  If it puts out tons of heat then your problem is most likely in the sensors.  "

 

When I did this it wouldn't kick out much heat. It was still luke warm.

 

My cell phone was sitting in the phone tray and when I went to pick it up it was freezing cold. 

 

I will check the coolant reservoir as I have not looked at it. 

[Haufski762]

I checked both coolant levels and they are about half way up each reservoir after the truck sat for 2 hours. 

[Silverado4x4]

1 hour ago, Haufski762 said:

I checked both coolant levels and they are about half way up each reservoir after the truck sat for 2 hours. 

Turn on the recirc. With temps that cold wth recirc off your pulling outside fresh air in and the system has to heat that air also just press the button the little light will come on meaning in recirc mode. You will hear the difference in the fan.

Edited January 14, 2024 by Silverado4x4

[Haufski762]

Thanks. I did try it with both recirc on and off and there was hardly any temperature difference. I could hear the fan noise changing.

Edited January 14, 2024 by Haufski762

[Haufski762]

I called the dealership and they said with the -20/30 temps we have had, they have had a rash of both gas and diesels trucks coming in with issues. 

 

I asked them if there was a factory winterfront for these trucks and they said no. Some online forums say the grille louvers are supposed to act as a winter front but they don't stop 100% of the air coming across the radiator. 

 

I did find an aftermarket winter front but it wanted you to use buttons to secure it to the grille. Not going to modify a new truck with those. 

 

Does anyone have a lead on a winterfront that you don't have to modify the truck to use? 

[Naughty Donkey Performance]

A piece of  cardboard in front of the radiator used to do the trick!

Spray paint it black if you need it to look good, my 2020 6.2 has to be on 75 or above to get any heat on the feet, always been this way, I believe others have the same issue and there is likely some sort of issue with the venting system not operating correctly.

[Haufski762]

Cardboard was my next option. Not my favorite but the cheapest for sure.

[calgator73]

When you did all these checks...what was your engine temp?  Another duramax forum spoke to kinked heater hose from the factory causing an issue.  Those trucks should produce as much heat as you can stand once the engine is fully warmed.

Edited January 15, 2024 by calgator73

[BigBadSierra]

There's just days the heater is not happy. This occurs all the time to me 72 is fine most times then some days it's to cool then when I bump it to 73 the truck gets to warm. Other days it's fine. The light coming through the windows from the Sun and even the color of Paint you have seems to mess with it. Even pulling my shade back on the sunroof causes it.

 

It's like the temp sensor in the cabin is easily fooled by outside factors.

 

 

[Haufski762]

5 hours ago, calgator73 said:

When you did all these checks...what was your engine temp?  Another duramax forum spoke to kinked heater hose from the factory causing an issue.  Those trucks should produce as much heat as you can stand once the engine is fully warmed.

 

Engine temp was in its normal range. 

[calgator73]

31 minutes ago, Haufski762 said:

 

Engine temp was in its normal range. 

Back to the basics.

 

Check and compare the temperature of the two heater hoses going to your core.  Better if you have an infrared thermometer.  Supply should be uncomfortably hot and return should be a slightly lower temp.

[Haufski762]

1 hour ago, calgator73 said:

Back to the basics.

 

Check and compare the temperature of the two heater hoses going to your core.  Better if you have an infrared thermometer.  Supply should be uncomfortably hot and return should be a slightly lower temp.

 

Ill just take it to the dealership. 

[silveradosid]

the 2.7 and 3.0 both use the same heat management system, and i think when it that cold out the electric pumps slow down to keep the engine hot. the slow circulation in the heater core is not allowing good heat in the cab. my 2.7 is the same way at minus 10 or colder, i can drive 50 miles and still only get luke warm air in the cab with the heat set at its maximum