The heater valve is a very important part of a vehicle’s heater system. It’s usually located behind the vehicle dashboard. It works independently of the rest of the cooling system and controls the amount of coolant that is flowing through the heater core. The coolant that flows to the heater core travels through the heater hoses. These hoses connect the engine to the heater core. There are however, some vehicles which don’t use a heater valve. In this case, the coolant will flow freely from the engine to the heater core via the heater hoses.
The heater valve can be a manual valve, a vacuum valve or electrical.
The heater valve can have problems with not opening and closing as it should. This could be caused by it sticking. In this case, some WD40 or other lubricant may help. If it doesn’t however it may need to be replaced. If your heating system isn’t working and is bled properly, it may be an issue with the heater valve. Alternatively, if the vehicle’s heating is always on it may be an issue with the heater valve being seized open.