New guy here with heat question

[JK360]

Hi guys, Im new here... Ive been reading a lot of the threads and ive already learned so much. I picked up a 97 ECSB 1500 Z71 5.7 on saturday and im in the process of doing a lot of maintenance and upgrades. It has 189K miles but still runs smooth and strong.

Only major concern right now is the heat or lack there of. The heat blows warm/cool air no matter what setting or blower speed. The blower works on all speeds, and as far as i can tell, the blend door is functioning properly. II hear noise when going from hot to cold and it changes from the vents to defrost normally. After reading here and other sites, I first flushed the heater core and that didnt solve it. I then "burped" the system... atleast i think i did. nothing. Today i replaced the thermostat and still no difference.

From what i can tell, the hose going to the heater core gets warm/hot, the one out is much cooler, and the top radiator house doesnt seem to get a lot of pressure in it but it gets warm/hot. I can basically squeeze it closed with my hands after the truck has been running for 20 minutes. One thing i noticed is the truck runs cool. the temp gauge doesnt really go past 160 even after driving for 2 hours.

Im stumped on this one. Im confused on if there is a valve controller and if its electronic/cable/ or vacuum. Any help is greatly appreciated as this is something i need to resolve fast. And thanks for all the tips ive recieved so far from reading the other threads. So far ive done the silencer mod on the intake, next will be the intake fin removal, and after that i dont know yet haha.

 

[SCOTTYINWV]

Is your fluid level full, and how did you flush the heater core?

 

[JK360]

I disconnected the hoses at the firewall and hooked up a hose to the out and flushed it out the in to clear anything that was clogged. And yes all the levels are full.

 

[SCOTTYINWV]

Did you use compressed air? And then run water through it to make sure it comes out good?

 

[SAATR]

If one heater hose gets hot and the other does not, then you either have a malfunctioning heater control valve or a plugged heater core. If the valve is working, the line going into the firewall should be hot, and would indicate a plugged heater core. If the hose is not hot after the valve, then the valve is faulty or not getting a vacuum signal from the control head. The best course of action with a plugged heater core is just to replace it, as they are neither expensive nor hard to replace. The valve is also cheap and easy to replace. If the valve isn't getting vacuum, then you may have a bad vacuum hose or an issue in the control head, which is a whole other can of worms.

If your hoses aren't being pressurized when the engine is up to temperature, then you have a coolant leak. These trucks are notorious for back intake gaskets and heater hose quick connect fittings on the intake. Check the intake and hose connections closely to see if you are having one of those issues.

 

[1997chevydriver]

If one heater hose gets hot and the other does not, then you either have a malfunctioning heater control valve or a plugged heater core. If the valve is working, the line going into the firewall should be hot, and would indicate a plugged heater core. If the hose is not hot after the valve, then the valve is faulty or not getting a vacuum signal from the control head. The best course of action with a plugged heater core is just to replace it, as they are neither expensive nor hard to replace. The valve is also cheap and easy to replace. If the valve isn't getting vacuum, then you may have a bad vacuum hose or an issue in the control head, which is a whole other can of worms.

If your hoses aren't being pressurized when the engine is up to temperature, then you have a coolant leak. These trucks are notorious for back intake gaskets and heater hose quick connect fittings on the intake. Check the intake and hose connections closely to see if you are having one of those issues.

Pickups dont have a heater hose valve. So he can rule that one out

 

[SAATR]

Pickups dont have a heater hose valve. So he can rule that one out

I thought about that, but wasn't sure, as I have more experience with SUV's than pickups.

 

[JK360]

Ok, I didnt use compressed air cause i dont have a compressor i just used water. i did it in both directions till the water was coming out clear. As far as the valve, thats where i was confused. Would the actuator door have any play in this? Since only one heater hose is getting hot probably not right? If not I guess i will look into replacing the heater core.

 

[SAATR]

If water flowed through the core without an issue, then it shouldn't be plugged, and shouldn't need replacement. The actuator wouldn't cause the outlet line not to get hot, so you still have a flow issue somewhere in the system.

 

[SCOTTYINWV]

I would have the cooling system pressure checked