Why does the heater put out heat when it is set on cool on a 1978 corvette?

In a 1978 Corvette, if the heater blows warm air while set to cool, it may be due to a malfunctioning climate control system or a stuck blend door. The blend door controls the mixture of hot and cold air, and if it is stuck in the position that allows hot air to flow, the heater will still emit heat. Additionally, a refrigerant leak or low levels could prevent the air conditioning from functioning properly, leading to warm air being circulated. Regular maintenance can help diagnose and resolve these issues.