Luke Warm Heat

[oldbrown]

Have a 91 K1500. Truck gets up to temperature but heat is only about 105 out of the vents. I flushed the heater core and put in a new thermostat with no real changes. Only other thing I can think of is the coolant is not circulating well. No noises or leaks from water pump. Any ideas? Thanks.

 

[smdk2500]

Are the hoses on the inlet and outlet of the heater core the same temp or is one significantly cooler then the other one?

 

[studigggs]

Blend door actuator could be toast or the flap that allows the air to move through the heater core could be jammed.

 

[Brandon Schnautz]

Blend door actuator could be toast or the flap that allows the air to move through the heater core could be jammed.

I'm going with this guy ^

 

[Kv5137kv5137]

CHeck the heater hoses. If they get hot. Check the upper radiator hose. Both should get hot. Open the havoc. Heck the blend door operation. Two or three depends. Fan? Check the way the heater core is positioned it should be insulated with that brittle factory foam if not but some and seal it. That is what was wrong with mine


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[bamabound]

either bad heater core or blend door actuator. i'd guess heater core is plugged up. my brother just had the same symptoms & it was the heater core. he said it was pretty easy to replace.

 

[xx94Z71xx]

when you flushed your heater core did u back flush it? in the out and out the in? thats what i had to do to unplug mine. i kept alternating which side i put the hose on. i did that a couple times and it was clear water then bam it was sludge city. My heat was like 10x hotter afterwards but i spent a good hour or two doing that.

 

[oldbrown]

Thanks guys
I plan to look at the blend door