Is there a filter or something else on a 1977 corvette that keeps the air conditioner from blowing right
There are doors in the HVAC system that direct the air to the outlets. They are operated by vacuum motors and your vacuum tubes may be leaking.
POSSIBLE YOU'RE SYSTEM IS LOW ON REFRIDGERANT GAS.
Search Chevrolet Corvette Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Chevrolet Corvette Experts