Heater Control Valve Replacement
What is a heater control valve?
The heater control valve moderates the amount of heat the cabin gets when the heater is in use. It does this by regulating the amount of hot engine coolant that can enter the heater core.
When little or no coolant flows into the heater core, the air from the vents will remain cool. When the valve opens, the air will turn very warm. The valve is regulated by the temperature control dial or slide in the cabin.
What are the symptoms related to a bad heater control valve?
When the heater control valve fails, adjusting the temperature may not change the air temperature at the vents, whether hot or cold. Also, the valve could leak engine coolant, possibly causing the vehicle to overheat.
Can I drive with a heater control valve problem?
If the heater control valve is leaking, you shouldn't drive the vehicle — overheating can result from any coolant leak. In this situation, it's best to have the vehicle towed to a repair shop.
If the heater control valve is simply unresponsive, it won't affect drivability in any way. But if you live where the temperature drops below freezing during the winter, you could be in for an uncomfortable ride.
How often do heater control valves need to be replaced?
The original heater control valve for most vehicles should last for about 100,000 miles. Low-quality replacement heater control valves will more than likely fail much more quickly.
It's worth noting that not all vehicles are equipped with a heater control valve.
How are heater control valve issues diagnosed?
Heater control valves are easily diagnosed by observing whether the valve responds when the temperature selector is adjusted.
If there is movement at the valve, but no change in heat, the valve will be removed and inspected. The valve may just be failing to move, or it may be leaking engine coolant. In both cases, the heater control valve is replaced with a high-quality or OEM part.
How is a heater control valve replaced?
The heater control valve is separated from the heater core hoses and control mechanism, which could be a vacuum line or a cable. Then the valve is removed from the firewall, and replaced.
Installation is the reverse of removal, and some adjustment may be necessary if you're dealing with a cable-type controller. After the repair, the engine coolant should be filled and bled of air.
RepairPal recommendations for heater control valve issues
This is a good time to check the heater core hoses and replace them if they're leaking or corroded. A thorough cleaning inside the heater hose ends usually helps prevent a leak. It's also a smart time to check the condition of the coolant.
There are many brands of heater control valves, and many are universal. Low-quality heater control valves may fail prematurely, leading to the same repair in the future.
Can I replace the heater control valve myself?
This is a great DIY project. It is low in difficulty, and very few tools are required. The novice DIYer should beware of hot engine coolant, and let the vehicle cool before attempting this repair.
If you're not familiar with the heating system, or aren't sure if the valve is the cause of the problem, it's best to leave this repair to a professional.