Heater on 1994 Cadillac Sedan DeVille

I was planning on shipping my 1994 Cadillac Sedan DeVille from warm Hawaii to New Jersey tomorrow. Although I have used the heater once or twice before on unusually cold nights when the temperature was about 60 degrees F when I tried it last night at about 70 degrees F it would not turn on even when the electronic controls were set at 90 degrees F and high fan. I called the Cadillac roadside assistance number and they had a tech call me back. His take is that the computer won't allow the heater to turn on when the outside temperature is not cold enough but until he gets back to his office tomorrow he can't say what that temperature has to be to allow the heater to turn on. Doesn't seem to be any reference to this in the owners manual.

If anyone has any detail knowledge on this please help asap. The reason I tested the heater last night is that the car is headed to NJ for my daughter and grandaughters to use and I don't want to send them a car without heat in the middle of the winter. On the other hand I don't want to try to "fix" the problem here in Hawaii when it might not even be broke. Possibly there is a way to fool the computer into thinking the outside temperature is cold enough to allow the heater to turn on.

There is no sensor to keep heater from working. As long as thermostat is working properly you should have heat to your heater core. Now is the blower motor not coming on? If this is the case the blower motor is probally bad. They have a lot of problems with them. They have the control module for the blower motor built right into the motor. If the motor is working just not hot it could be a temp door problem. If blower works and it heats up but you have no air volume then I would look at the evaporater core for being externally plugged.