Cadillac Repair: 1977 Cadillac No Heat Blower works, vacuum line, heater hoses

Question
The blower works but there is no heat. What steps should I take to find and fix the problem?

Answer
In one of the heater hoses that goes thru the firewall there is a WATER VALVE that has a vacuum line on it. Remove the vacuum line and see if you now have heat . There should be NO vacuum at the vacuum line. If you still have no heat replace the water valve in the heater hose.