Sound like your temperature blend door is stuck in the cold position. To check that, take the blower motor control module out of the evaporator case and look into the opening. The blend door will be a rusty flat part.
Set the HVAC controller to 90° (the highest setting) and look at the blend door. It should be in this position:
If it is not there are several possibilities. The blend door position is controlled by the blend door motor. There is a metal link between the door and the motor. That link might not be attached. The blend door motor with the link looks like this (from the top):
You can test to see if the blend door motor is working by briefly removing the CTSY/CLK fuse. That will cause the HVAC control head to forget its settings. The next time you turn on the ignition it will recalibrate the blend door by moving it to the maximum heat position and the maximum cool position. It takes about 15 seconds to do the calibration. You can see all this happening through the blower control module opening.
If the motor moves OK in one direction but not in the other direction, then the HVAC programmer might be bad. It is attached to the firewall above the gas pedal. It is quite common for the resistors associated with the blend door motor to overheat and either cause bad solder connections or for the resistors themselves to burn up. The resistors in question are shown in the lower left corner of this picture:
You can see how the PC board has been discolored by the heat from the resistors. It is also possible that one of the transistors for the blend door motor has failed.