Cadillac Repair: 1993 Cadillac S/D 4.9 liter heater problems, flow control valve, heater hoses

Question
When I turn my heater on low i get warm air, when i turn it on high i get cool air.

Answer
with the engine at normal operating temperature feel the 2 heater hoses that go thru the firewall into the heater core. One should be extremly HOT and the other slightly cooler. If they are, You either have a problem with the heater flow control valve or the AC/Heater oprogrammer.

I would first suspect the heater flow control valve