The heater control valve (or hot water valve) opens
to allow hot coolant from your engine to flow through the heater core
. Air from either inside or outside the vehicle then passes through the hot heater core, which warms the air before it enters the passenger compartment of your vehicle.
How does a vacuum heater valve work?
The heater control valve
either permits or restricts coolant flow through the heater core
, depending on whether vacuum is applied to it. It is a normally OPEN valve which closes when vacuum is applied. When the valve is open, coolant circulates through the heater core and you have heat.
How do you test a heater control valve?
- Bring the engine up to operating temperature and switch the heater to the hottest setting.
- Check the temperature of the valve's outlet hose (between the valve and the heater core)—it should feel nearly as hot as the valve's inlet hose.
How is a heater control valve controlled?
The heater control valve (sometimes called the hot water valve) is
used to control the rate at which coolant flows through the heater core
. The valve is located on the heater inlet hose. Manually operated systems may use a cable, a vacuum motor or an electric solenoid to operate the valve.
Can you bypass a heater control valve?
Heater control valve bypass is not standard on vehicles;
it is a modification
. When bypass hoses are installed, the coolant in your car will always be circulating through the heater core – that means that if the core starts leaking, you won't be able to turn it off.
Can you test a heater control valve?
How to test a heater control valve.
Adjust the heat to the full on position
with the engine at operating temperature. Then check the temperature of the hose on the inlet and outlet sides of the heater control valve. The inlet and outlet hoses should be the same temperature.
What causes a heater control valve to go bad?
Over time the heater control valve can wear out and crack, which will cause coolant to leak from the valve. Heater control valves can also leak from excessive corrosion from contact with old or contaminated engine coolant.
Where is the heater control valve located?
The heater control valve allows the flow of coolant through the heater core to be controlled and switched on and off without affecting the operation of the rest of the cooling system. It may be located
on the inlet or the outlet port of the heater core
and activated by a cable, electronic control, or a vacuum signal.
How long do heater control valves last?
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.
Why is my car blowing cold air when the heater is on?
Problems with the vehicle's heating system can be either no air or only cold air coming out of the heating system. A car heating system blowing cold air can be due to
a faulty thermostat, low coolant fluid level
, malfunctioning heater core, a leaking cooling system, or problems with heating controls and blend door.
What are the symptoms of a bad heater control valve?
- No heat comes out.
- Heat is always on and you can't turn it down.
- Heater operates erratically, putting out more or less heat without any control changes.
- Coolant leaks.
- Low coolant level.
- Higher-than-normal temperature gauge readings (from loss of coolant)
How do you clear a clogged heater core?
- Step 1: Locate the Heater Core. First thing's first. …
- Step 2: Disconnect the Heater Hoses. …
- Step 3: Apply the Pressure. …
- Step 4: Hit it with the Hose. …
- Step 5: Reconnect the Heater Hoses. …
- Step 5a: Flush your entire cooling system with Thoro-Flush. …
- Step 6: Refill the Coolant.
Can heater control valve cause overheating?
Another symptom of a problem with the heater control valve or it's hoses or connectors is a
coolant leak
. … A coolant leak at the heater control valve is not only a problem in that it will disable the heater, but it will also compromise the cooling system which can cause the engine to overheat.
How can you tell if you have a bad heater core?
- Fog Inside Your Car. Two things could be going on if you have fog inside your car. …
- Sweet Smells in the Car. The sweet smell in your car might not be your perfume or the donuts you're taking to work. …
- Constant Engine Coolant Loss. …
- Cold Air in the Cabin. …
- Cold Cabin/Hot Engine.
What is the job of the heater control valve quizlet?
Sometimes called the water flow valve,
controls the flow of coolant into the heater core from the engine
. In a closed position, the valve allows no flow of hot coolant to the heater core. In an open position, the valve allows heated coolant to circulate through the heater core, maximizing heater efficiency.
