Climate Control Diagnostics Access

How do you access the self-diagnostics of the GM Climate Control System? My father has a 94 Buick Park Avenue that will switch to full heat. It can be "corrected" by turning off/on.

Thanks

When I turn the climate control off, I have cold air blowing on my right ankle and foot as I drive. When I raise the hood, I can see into the firewall. Could the air be hitting the windshield and coming into the car through the firewall?

How do you access the self-diagnostics of the GM Climate Control System? My father has a 94 Buick Park Avenue that will switch to full heat. It can be "corrected" by turning off/on.

Thanks

you'll get into diagnostic mode by pressing off and warm buttons at the same time for a few seconds, then your display starts to flash and will give you any numbers to display what might be wrong...