I posted this in another thread last week and got no responses so i'm reposting hoping for help.

I am working on my GF's 96 LT1.
She has owned it since it was new.

Complaint, no heat.
She had radiator flushed at jiffy lube type place and since then has no heat.
I told her to take it back but she doesn't want to deal with them.

So i said I would check it out.
I checked thermostat last week using pan on stove method. worked fine
Also:
Pulled hoses coming off water pump and flushed from both sides.

Getting clear water out of all hoses both directions.

Reattached, filled system, bled system, fan blows fine, little to no heat still.

Any ideas?
me and my gf appreciate the help.

 

You might need to check operation of the heat **** to be sure the cable is operating the mix door.

 

Is there a write up for this, i searched your site (awesome btw thanks for all the info) but did not see one for the heat ****.

This morning it was 28 out, so i let the car warm up for 20 minutes, went out and it was blowing cool air still with **** all the way in the red. I slowly turned it to cold and noticed significant increase in airflow coming from the vents as i did this, if i turned it back to hot the airflow decreased (but there was still air blowing out). Also i noticed if i turned it to cool fairly quick and let go, it would spin back to hot on its own.

whattya think?

**edit**
wanted to add that after driving for 30 minutes or so with heat on, i pulled over and checked hoses at heater core/firewall. Looking at connections, the one on the right is definitely hot, the one on the left is not as hot as the one on the right, but is warm. What should the difference be in these?

 

Both hoses should be hot! I know that sounds stupid, but let me explain. The heater core is built like a small radiator. Coolant is supposed to flow through freely and heat the core up. As stuff cloggs up the core the flow is reduced and it cools down with the fan blowing on it.
Feeling the hoses with your hand, you won't be able to tell a difference between hoses if things are flowing. Try it on another car. I've measured it with one of those point and shoot thermometers and it's only a few degrees difference.
How do you fix it? There's only one thing I've been sucessful with other than replacing the heater core. You have to flush the heater core. Pull the heater hoses from the engine. Get the stongest coolant flush you can find and pour about a whole bottle into one of the hoses. Let it sit in there for about ten minutes. Then using a garden hose with a regular spray attatchment, hold it to the hose and slowley squeeze the handle. Not all the way, only about 1/4 of the way. Remember, you're dealing with acid here and you don't need any suprises. Also, if it's restricted you can build up some pressure and burst the core. Flush one way, then the other. I ususally have to repeat this process two or three times. Good flowing heater cores will flow the garden hose wide open. Restricted ones, well, won't.

 

ok, thanks will do that.

if i have spare hose laying around do you see a problem with me just attaching it right at the heater core firewall junction and flushing?

 

Any way you can get connected if fine. I just usually leave to hoses connected to the heater core. By the way. The larger hose is the supply hose and the smaller is the return. To back flush, spray water into the smaller hose.

 

ok will try this out again after the ice melts...

 

so the outside temp is above 50 again and i figured i'd give this a go.
i followed everyone's advice and flushed the heck out of this core again, both directions, and got quite a little bit of green rubbery stuff, black stuff and some hardened antifreeze chunks out. right now i have pure radiator flush fluid soaking in just the radiator core for about 15-20 minutes and will go flush it both ways again. will post back when i fire it up.

thanks again

 

VICTORY!!!

blazing heat again.

Thanks everyone

 

Chaulk one up for the little guy! That's great to hear you got it cleared out.