Hi
I have a 83 Z28 with 86 LG4 in it. Where I live the temp fluctuates a lot, and I do plenty of short drives, so I have a dual snorkel air filter setup, with dual heat risers. The thermac works when the engine is cold, but sometimes when i stop and open the hood I notice the flaps are still in the closed (allowing hot air only) position. This will happen even after driving for 5-10 minutes. I checked the temp sensor above a propane heater, and it released vacuum (doors opened), but it doesn't seem to work on the car all the time. For info, thermostat is a 180, i have half the radiator blocked off, and air temp is 20-40 degrees F recently.
Do you know about what air temp or water temp is required to open the thermac?
As a side note, I tried hooking the thermac ducts up to the TVS becuase I read that the TVS "switches" at ~90 degrees F coolant temp. I figured that would be about perfect to help engine warmup, when cold the vacuum pulled the doors shut, but the problem is it didn't let the doors open either!

Thanks for any help
Jeff

 

I'm not sure what sensor you're talking about... hopefully you have the right one (the one IN the air cleaner).

What you may not know is that it's adjustable. If you cut the plastic cover off there is an adjustment screw that allows you to set when the the Thermac opens.

Mine opens fully at 60*F.

 

Hi
Thanks for the idea! I did notice a screw in the air cleaner sensor but didnt think to mess with it. I will have to try that. Any chance you remember which way to turn for lower temp opening?
By the way, I was talking about using the TVS switch, is it one of the temp sensors in the water neck/intake manifold that has 2 vacuum ports.

Jeff

 

The TVS switch in the intake manifold is either for the EFE valve or for the canister purge, I can't remember which. It shouldn't have anything to do with the Thermac.

As far as which direction, no, I don't remember. The easiest way is to have the air cleaner at inside room temperate and then turn the screw until it opens. Of course that requires a vacuum pump .

You could do the same thing on the car...

I set mine by taping a lead from a digital thermometer right next to the sensor.