2001 Silverado -No heat (not actuator)

[TJay74]

I have already replaced the actuator, as it was bad. Now here is the funny thing. I dont know if it was just because at the time it was warm out but on the old actuator the heater worked as it got really hot. This was though while outside ambient temps were in the 55° plus range. Replaced the bottom actuator module and now I have hot and cold movement, but now with the weather in the 35-45°range I only have luke warm heat.

 

I checked the radiator hose, it is very hot like it should be. I checked the two lines coming out of the water pump into the heater core, one is really hot (same temp as radiator hose) but the other one is not very hot.

 

Why would I have heat before and not now. I found an article on this site about some seal under the wiper cowl needing to be replaced.

 

So has anyone seen this before. Would you lean towards bad heater core (how hard is one to replace in a 2001 silverado) or is it this seal under the wiper cowl?

[txab]

I'd leans towards a plugged heater core. Reverse flush the core and see if that clears the problem. Also make sure your cooling system is full as it should be.

[TJay74]

Reverse flush, yeah that is a pain and is going to suck. Have to find some way to remove the lines and not lose the entire system fluid. Ugh....lol

[txab]

Just disconnect at the core. You can pinch off the lines so as not to loose to much fluid. Then just flush with plain water

[gmtech4]

and replacing the htr core is NOT a DIY job as the whole dash carcass has to be pulled back and up slightly to remove the core ....

 

not fun at all.....trust me

[TJay74]

Thanks, I will try the pinch the line trick with some hoses on the inputs to the core and see if that works. And thanks for killing my thoughts on the core change out, figures it would be the suck.

[gmtech4]

ya it is ,then a few yrs later workin on base i had a blend door tit that broke and i had to remove the whole carcass and pull the entire htr box out and split it to replace the door .....

 

wholely chit what an event that was and i was a gm tech for yrs lol !!!