What's the deal? Wont shut off or respond to...

Question

Installed in my shop is a Intertherm E3EB012H electric furnace. It is wired correctly (to power at least) and I used a multi-stant "thermostat wire" to connect a Nordyne digital therrmostat (dont have the model # with me at work).

When double pull 60 amp breaker(s) are turned on, the furnace comes alive with a low blower speed and heats the coils (this is with the thermostat turned off). When the thermostat is turned on, the blower speed kicks up and it cools the coils down (obviously due to increased air flow).

The furnace will not shut off by any control of the thermostat and the temp setting will make no change in blower speed. I have checked and rechecked the thermostat wiring and it appears correct (red/ white green/ grey).

HELP!!!!