I have a '97 with 6 speed and the heater has never worked properly. Now it's getting cold it's an issue. So here's the problem:

Start car, let idle long enough to get up to 210, but blowing cold air.

Start driving, temp went down to 120 then up to 200 then down etc.

Took it to my mechanic for new thermostat and just picked it up; guess what?

Temp not getting above 12 and not blowing any hot air!

What now, heater core bad? Any help greatly appreciated as it's too damn cold to put up with now and won't even defrost the front screen.

Thanks!

 

I"m not really sure about the 97's as I own a 95 but here is an article by Shoebox you may want to check out. I'm sure someone will correct me if I'm wrong. 4th Gen LT1 F-body Tech Articles

 

Yes, the procedure would be the same for all 93-97 LT1's. Plugged heater core is a very common problem.

After you get done, be sure to follow Shoebox's guide to filling the system and bleeding air. Sounds like you may already have a problem with air in the system.

 

in order to do the flush do i need to remove the 90 deg elbow off at the TB to get to lower heater hose cause it looks hard as hell to get to?

 

Assuming you mean the air duct elbow, and not the 90-deg elbow that connects the steam pipe to the plate on the bottom of the throttle body, removing the elbow will make the access easier.

 

I had the same issue. Mechanics could never figure it out. I decided to change my heater core(super easy, 20min job) and still no heat. I finially found out that the metal tubes that connect to the rubber ones that run to the heater core were completely clogged with no salvaltion. A quick change on those and I had heat! First time in 2 years!