[quote]ORIGINAL: Colorado_Mustang

You should have heat well before the thermostat is shown to open on the temp gauge. Even 100* fluid going through the heater core will provide warmth. I'm usually turning down the heat when the gauge reads 150*.
[quote]

I have found just the opposite. When the motor is cold
the thermostat is Closed. When it is closed there is
No circulation. Hense no flow of any water through
the heater core. I believe that is why there is a small baypass
on the water pump.
That is why I cannot get any defrost when the car is
heating up untill a little after the thermostat opens
and the water starts circulating.

nitrousjunkie347
An easy way to check the flow through the heater
core is to pull both hoses to the firewall. You
should be able to blow (no air pressure) with your
mouth to see if it is clear.
Don't swallow any prestone.
Changing the heater core is a bi*&H