need help with no heat: 96 tahoe

DVR4 · Jan 3, 2014

I have a 96 tahoe 2dr. This morning it was in the 20's and I had no heat.
I'm going to flush the radiator, heater core, change coolant, t-stat & hoses. I need to see about getting it blowing heat first. A little cold for the work this weekend. The vacuum hose on the heater valve was disconnected when I bought the truck. Heat seemed to work. Hooked it back up and now no heat. I will disconnect to get warm air but would like to fix it properly. Any help trouble shooting would be helpful. Thanks in advance.

Also, what coolant should I use? I've seen several posts suggesting to avoid dex-cool

JDFabworks · Jan 3, 2014

I've got a 95 2dr. With exact issue today. It was working fine until this morning when it was 31 degrees, I checked vac line at water heater control valve and it was attached. I detached it but no change. Idk if my issue is in the control panel on dash or another issue. Blower works fine but blows cold.... Not good on cold days lol

lesterl · Jan 3, 2014

Heater valve should have a solenoid that controls the vac.

You can for now remove the valve and use a couple nipples to connect the hoses.
-assuming the heater valve is bypassing the heater core... Newer trucks dont have them.

JDFabworks · Jan 3, 2014

How often do those heater valves go bad? I'm new to these Tahoes and Chevys in general, so any insight to this is greatly appreciated

lesterl · Jan 3, 2014

IDK that the valve goes bad, possibly the solenoid or more likely the control head....

DVR4 · Jan 3, 2014

Thanks for the info. I just unplugged it and have heat again (makes me think the valve works).
I have a new control valve ($12) otw. I will see what happens and report back. If that doesn't work I will replace the solenoid and vacuum line. Control head seems to be ok. If not I will replace it or keep pulling/connecting the line and needed.

JDFabworks · Jan 3, 2014

Excuse my ignorance guys, but the control head, is that on the dash control or underhood? A pic would be great if possible.

DVR4 · Jan 3, 2014

JDFabworks said:
Excuse my ignorance guys, but the control head, is that on the dash control or underhood? A pic would be great if possible.

it's the dash mounted heat/air/defrost control

JDFabworks · Jan 3, 2014

Ok thanks for the info. I noticed too that when I turn my vent control from defrost to forward vents it doesn't change. Maybe it is my control head that's gone bad.

lesterl · Jan 3, 2014

Control head is probably bad, I had to jack around with mine untill I got tired of it, found one for a suburban that worked fine at a junkyard...

JDFabworks · Jan 4, 2014

lesterl said:
Control head is probably bad, I had to jack around with mine untill I got tired of it, found one for a suburban that worked fine at a junkyard...

Is the control head the same thing as the Blend Door Actuator that the parts houses have listed?

JDFabworks · Jan 4, 2014

Well, my actuator works fine (one near gas pedal). But still don't get flow velocity in forward vents when putting dial in that position. I removed vac line from heater control valve under hood and I got heat through defrost and defrost/feet. So, I assume my solenoid may be bad then?

lesterl · Jan 4, 2014

Control head sits in the dash and has 3 knobs, fan speed, temperature, and position of airflow.

There are 3 actuators, the one near the feet adjust position of airflow, mine on my sierra wasnt flowing air off of dash vents, found the diverter had popped out of position. Took cover off heater core box, used a washer and restabbed the diverter. Works fine.

JDFabworks · Jan 5, 2014

lesterl said:
Control head sits in the dash and has 3 knobs, fan speed, temperature, and position of airflow.

There are 3 actuators, the one near the feet adjust position of airflow, mine on my sierra wasnt flowing air off of dash vents, found the diverter had popped out of position. Took cover off heater core box, used a washer and restabbed the diverter. Works fine.

Ok, thanks. I'll try and check my diverter also. Is it a pain to get to behind dash or not too bad? I assume I need to pop glovebox out to get to the cover? Again, excuse my ignorance...

lesterl · Jan 5, 2014

Heater core cover sits on bottom of the air handler right above the passenger feet area. If you look at servo (actuator) above drivers feet should be 3 spring loaded white plastic pieces that drive 3 diverters, betcha one isnt working right....

branden · Jan 29, 2014

i had the same problem with my 99 it was blowing but not hot i did ever thing i could thank of i put a new temp door actuator new heater control valve put a new thermostat nothing fix it so i pulled the door off the heater core and my heater core fell down and air was blowing across the top of the heater core instead of through it so i put it back up and it did fix my issue......for about 6 months now it blowing cold all over i check my heater core and everything else i notice that my hose from the water pump to heater valve is cold and the hose from the heater valve to the intake is hot i have no idea whats going on can any one help me out

lesterl · Jan 29, 2014

Sounds like maybe your heater valve is not letting coolant pass, either valve is stuck, solenoid is bad, no vacume present, or control head is bad.

branden · Jan 29, 2014

i don't have vacuum but it has not worked since the last problem

lesterl · Jan 29, 2014

Should be manifold vacume on one side of the solenoid and the other to the valve's vac motor....

branden · Jan 29, 2014

yeah it is i thank the the little vacuum canister is bad can i just bypass the heater control valve all together and just run the hose straight to the heater core

need help with no heat: 96 tahoe

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