Cabin heater not getting hot

[firefighter_2000]

I have about a 25 mile commute to work and the heat will not get hot. I noticed this towards the end of winter last year & flushed the heater core. It flushed clean with no problem. Didn’t seem to make a difference, and warm temps arrived and I kinda forgot about it. First cool temps this fall and it’s still not warming up to normal. It gets warm, but not hot like normal. I can run the temp down to cold and it turns cold, then back up and it goes back to warm, but again not hot. It’s almost as though the blend door inside the hvac box isn’t opening to the hottest temp. If anyone has any suggestions on what to check next, I would appreciate any new ideas!
Thanks
Craig

 

[gsbrockman]

What coolant are you running?

 

[firefighter_2000]

What coolant are you running?

Stock OAT coolant. Level is good.

 

[gsbrockman]

How many miles on the truck? Did this occur anytime close to the time it was deleted?

 

[firefighter_2000]

Truck has around 124k now. I believe the delete was either just before it started acting weird. I honestly can’t remember 100%. The delete was around 105.

 

[crazy jerry]

first thing to check is if both heater core hoses are fairly hot.

 

[Hoefler]

Reverse your heater hoses on the core, you may have an air block. The hot/supply goes into the bottom of the heater core.

 

[brucejohnson]

Typical symptom of a faulty, incorrect or missing thermostat...

 

[firefighter_2000]

Forgot to add that info. Both hoses going to the heater core are hot. Truck runs at normal operating temperature. Pretty sure it’s not the thermostat.

 

[brucejohnson]

Forgot to add that info. Both hoses going to the heater core are hot. Truck runs at normal operating temperature. Pretty sure it’s not the thermostat.

Still, especially if it is the original 6 year old item, it is inexpensive and quick to put in a new "quality" replacement t-stat.

 

[firefighter_2000]

Still, especially if it is the original 6 year old item, it is inexpensive and quick to put in a new "quality" replacement t-stat.

I’ve actually got a new water pump & t-stat from Genos in the truck just in case something happens on the road. I actually replaced it around 75k when the water pump recall was done.
Craig

 

[Ozymandias]

Truck has around 124k now. I believe the delete was either just before it started acting weird. I honestly can’t remember 100%. The delete was around 105.

Seems they messed something up woth the hosing.

The line to the core must be to hot to touch.

 

[firefighter_2000]

Seems they messed something up woth the hosing.

The line to the core must be to hot to touch.

Both lines are hot to touch.

 

[Hoefler]

If the lines are reversed, there will be air trapped in the core and no way to purge it, both lines will be hot, and still no heat in the cab

 

[firefighter_2000]

1. goes to the bottom outlet.
2. goes to the top.

 

[Hoefler]

#2 should go to the bottom, it is the supply for the heater.

 

[firefighter_2000]

#2 should go to the bottom, it is the supply for the heater.

Maybe we’ve found the problem!

 

[crazy jerry]

Forgot to add that info. Both hoses going to the heater core are hot. Truck runs at normal operating temperature. Pretty sure it’s not the thermostat.

if both hoses are hot then your good. no air pocket, no clog. i would bet on the blend door malfunction

 

[Ozymandias]

if both hoses are hot then your good. no air pocket, no clog. i would bet on the blend door malfunction

Nope, if the inlet is on top then the heater core stays full with air and the hotwater inside is just like a waterfall, exiting on low. Same temperature as it entered the h.c.

 

[crazy jerry]

we can disagree then. ive switched hoses around and heater didnt know a difference