Heater Control Valve
WARNING: This page is about a different car, the 1999 Mazda B4000, 1999 Mazda B3000, and 1999 Mazda B2500. However, it is still accessible from the selected car via links, so may be relevant.
Start engine and let idle. Select mode. Check rod position and vacuum to control valve. See HEATER CONTROL VALVE ROD POSITION table. If rod position and vacuum appearance is not as specified, check the following:
- If vacuum exists in MAX A/C position but rod position is incorrect, replace heater control valve.
- If vacuum exists in A/C, vent, panel/floor, floor, floor/defrost and defrost modes, check vacuum control valve.
- If vacuum does not exist in MAX A/C mode, check for leak in vacuum lines and at vacuum control valve.
HEATER CONTROL VALVE ROD POSITION
| Mode | Rod Position | Vacuum From Vacuum Control Valve |
|---|---|---|
| MAX A/C | Extended | Yes |
| A/C | Retracted | No |
| VENT | Retracted | No |
| PANEL/FLOOR | Retracted | No |
| FLOOR | Retracted | No |
| FLOOR/DEFROST | Retracted | No |
| DEFROST | Retracted | No |