Buddy here at work has a 2000 ext cab short bed Z-71 5.3, starting to get colder in our area, The issue is he cant seem to control the temp,seems like he can hear water in the heater core, sounds kinda half full, gonna get more info out of him here in a bit.

 

Update, pulled all fuses, none blown, coolant lvl has not changed, as far as switches go he can control were and speed but not temp.

 

Can you get to both heater hoses easily?

If so, when engine is at operating temperature, and HVAC controls on HOT, see if both hoses are equally warm. If one's warm and one's cool, then heater core is clogged. If both are hot equally, then there's probably an issue with the controls themselves...whether it be the part where you adjust them, or the cables behind the dash.

 

Put a new thermostat in it, got a little better but as far as the hoses go, both are the same amount of heat.

 

blend door actuator is probably stuck or broken.

 

^this^...we see it alot after the battery has been disconnected...theres a procedure to resync the blend door, dont remember it off hand, but google should tell ya...if that doesnt do it its probably the actuator itself, pretty common

 

I've always done max cool, 5 sec, max heat, 5 sec, max cool, 5 sec, max heat again. Same for recalibrating air door actuators, move to each position for a few seconds.

 

Sometimes I had to physically unplug the control head for a few seconds rather than disconnecting the battery to get everything to work again. In several different years of trucks.

 

You guys are awesome, lets you know what happens later on tonight.

 

blend motor would only go about half way before it would stop, so thats on it's way and a cabin filter is gonna go in.