First, did you hook up the blend control correctly. It is what selects the air path, either through the evaporator for cold air, or through the heater core for warm air. Can you tell the difference with the ac on. Moving the control should select cold or ambient temperature if it is working now.
If that is working: there is no coolant valve, it flows through the heater core all the time (or maybe not in your case). Your heater core is probably clogged. Try removing the heater hoses at the engine and forcing water through them with a garden hose in each direction.
If that is working: there is no coolant valve, it flows through the heater core all the time (or maybe not in your case). Your heater core is probably clogged. Try removing the heater hoses at the engine and forcing water through them with a garden hose in each direction.
