Instead of being a single, easily identifiable valve, the heater control function is usually integrated into the HVAC system's blend door actuator inside the dashboard. There's no external "heater control valve" in the traditional sense like you might find on older vehicles.
Regarding a bleeder valve for the heater core itself: There isn't a separate bleeder valve for the heater core on a 1994 Cadillac DeVille. Air in the heater core is typically purged through the cooling system's overall bleeding procedure. This often involves opening the radiator cap (when the engine is cool!), running the engine, and monitoring the coolant level. Air bubbles should work their way out as the system warms up.
If you are experiencing heater issues (no heat, intermittent heat), the problem is *much* more likely to be one of the following:
* Blend door actuator: This is the most common culprit. It's an electric motor inside the dash that controls the flow of hot/cold air.
* Low coolant: Check your coolant level.
* Thermostat: A faulty thermostat can prevent coolant from reaching the proper temperature for heating.
* Heater core: A clogged or leaking heater core is less common, but possible. This requires more serious repair.
In short: Don't expect to find a readily accessible external valve for the heater. Diagnosing heating problems requires a more systematic approach focusing on the components listed above. A repair manual specific to your 1994 Cadillac DeVille will be very helpful.
