The purpose of a heater control valve is to control the flow of engine coolant to the heater core, located within the passenger compartment. When the heater or defroster is turned on, warm engine coolant passes through the heater core. Here a fan forces air across the surface of the heater core and then into the passenger compartment where the warm air is felt.
2) once I get the factory hoses off, I want to just replace them with non-quick disconnect heater hoses and just regular stainless hose clamps. Is there a problem with doing this? 3) what was the purpose of quick disconnect hoses, just to make it supposedly easier to get them off because they are way back behind the engine? Dec 10, 2015 Pop the tool behind the connector, and then pull of the hose to remove it. The tool remains on the pipe, don’t forget to take it off before installing a new hose. Cutting the disconnect can be done using a hand saw with a hacksaw blade or with a small air-powered reciprocating saw.
During times when the air conditioner is in use, the heater control valve closes, preventing engine coolant from entering the heater core. The result is less heat in the passenger compartment, allowing the air conditioner to work more efficiently.
Follow the step-by-step guide below for directions for replacing a faulty heater control valve.
- Note: It is important to remember that this is a general guideline. Therefore, be sure to consult your factory service manual for complete and detailed instructions specific to your vehicle.
Part 1 of 1: Replacing the heater control valve
- Warning: Be sure the vehicle’s engine is cool to prevent burns to the skin. It is also always a good idea to wear safety glasses to prevent any contaminants from getting into the eye.
Materials Needed
- Distilled or demineralized water
- Drain pan
- New engine coolant
- Pliers
- Ratchet set
- Screwdrivers
Step 1: Disconnect the battery. Loosen the hold down nut and bolt from the negative battery cable end and remove the connector from the battery post. This will prevent any shorts from damaging the electrical components.
- Tip: If the vehicle is an automatic with a shifter in the console, you may want to place the vehicle in low gear before disconnecting the battery to give you more space to work.
Step 2: Raise the vehicle. If you can not easily reach the lower radiator hose, jack the vehicle up and secure it on jack stands to gain better access.
Step 3: Place the drain pan under the vehicle. In order to catch the coolant that will be drained, you will need to put the drain pan underneath the lower radiator hose.
Step 4: Remove the lower radiator hose. Remove the lower radiator hose from the radiator by first loosening the clamp and then gently but firmly twisting the hose to ensure that it is not stuck on.
- Tip: Oftentimes the hose will stick as if it is glued in place. By twisting, you can break this bond and make it much easier to remove.
Remove the hose and drain the engine coolant into the drain pan.
Step 5: Locate your heater control valve. Some heater control valves will be located in the engine compartment at or near the passenger side firewall. Others are located behind the dashboard near the passenger footwell.
Refer to the factory service manual for your vehicle to determine the exact location. In this guide, it is assumed that the control valve is located behind the dash.
- Note: For the steps that follow, you will need to continue referring to the factory service manual for details about what needs to be removed and the location and number of fasteners that need to be removed as well.
Step 6: Remove the glove box assembly Open the glove box door and locate the attachment screws located along the outer edge of the glove box. Remove the screws with the appropriate screwdriver or ratchet and socket. Gently pull on the glove box assembly to remove from dash and disconnect any electrical connectors connected to the glove box assembly.
Step 7: Remove the dashboard. Locate the attachment screws, usually along the top edge and bottom edges. There may be other fasteners on the sides, depending on vehicle design. Remove the attachment screws using an appropriate tool. Gently but firmly pull on the dashboard and slowly remove it, making sure to disconnect any remaining electrical connectors that may prevent you from removing the dashboard.
Be careful not to pull on any wire or control cables.
Tip: Take pictures of how the wires and cables are routed and where all the electrical connectors go. Later you can use the photos to ensure everything is put back together properly.
At this point you may see the heater control valve, but in some cases you will need to remove the heater box to gain access.
Step 8: Remove the heater control valve Locate the mounting bolts or screws that hold the heater control valve in place.
Remove the fasteners with an appropriate tool and remove the valve. Pay attention to its orientation.
Step 9: Prepare the hoses. To help prevent leaks, thoroughly clean the interior of any hoses that were removed as well as the component you are reattaching it to.
Step 10: Install the new heater control valve. Install the new valve in the same position and orientation as the old valve.
Step 11: Reassemble the dashboard and glove box. Reinstall the dashboard, glove box, and any other components that were removed.
Refer to the photos you took earlier if necessary.
Step 12: Replace the lower radiator hose. Reattach the lower radiator hose and tighten the hose clamp.
Step 13: Refill the cooling system. Use a 50/50 mixture of antifreeze and distilled or demineralized water to refill the cooling system.
Step 14: Bleed all the air out. To get all the air out of the cooling system, you will need to start the vehicle, turn the heater on high, and allow the vehicle to achieve normal operating temperature.
Keep topping off the coolant as needed until the system is totally full, checking for leaks where hoses were removed and installed.
Step 15: Clean up afterward. Dispose of the used coolant in a manner that corresponds to local laws and regulations.
Each vehicle model is designed differently; therefore it is important to refer to the manufacturer’s factory service manual for your vehicle for additional details. If you would like a professional technician, such as one from YourMechanic, to replace your heater control valve for you, one of our mobile mechanics can work on your car at your home or office.
The statements expressed above are only for informational purposes and should be independently verified. Please see ourterms of servicefor more details
Step by step guide on how to replace automotive engine heater hoses, this article pertains to most vehicles.
Difficulty Scale: 4 of 10
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Tools and Supplies Needed
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- Replacement hoses
- Hose clamp tool
- Engine coolant
- Fluid catch basin
- Socket set
- Flashlight
- Pliers
- Exacto knife or razor blade
- Protective eye wear and gloves
Begin with the engine cold, in park with the emergency brake set, drain the cooling system.
Step 1 - Locate the heater hoses to be replaced and remove or relocate any obstructions.
Step 2 - Some vehicles use a spring loaded hose clamp which can be removed by using a special hose clamp removal tool, a pair of pliers can also be used. A worm screw style of clamp will use a screw driver to remove.
Step 3 - Once the tool has been installed, move the hose clamp to gain access to the hose mounting fitting. (Note: Heater hoses are connected to the heater core, this core is fragile so caution should be used when removing the heater hoses to avoid breaking the core and causing a coolant leak.)
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Step 4 - After the hose clamps have been loosened and relocated down the hose, use an exacto knife or razor blade to gently slice the hose long ways along the fitting.
Step 5 - Once the heater hose has been cut, gently lift and twist the hose to release it from the heater core fitting, repeat this process for the remaining hose.
Step 6 - Next, locate and remove the heater hoses from the engine which are usually near the engine water pump.
Step 7 - After the hoses have been released from the heater core and engine, remove any remaining mounting hardware and remove the hoses from the engine bay.
Step 8 - It can take a little ingenuity to configure the hoses for removal.
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Step 9 - Once the heater hoses have been removed, use a shop towel to clean the heater hose fittings to help seal the new hose installation.
Step 10 - Compare the worn heater hose set to the replacement hoses to ensure a proper installation.
Step 11 - After comparing the new hose set, install the hoses into the engine bay.
Step 12 - Once the heater hoses have been placed into the engine bay, connect the hoses to the engine using new hose clamps.
Step 13 - Next, position the hose clamp over the middle of the hose fitting and tighten securely, repeat this process for the remaining hose.
Step 14 - After the hoses are installed and clamps tightened, inspect for obstructions such as metal shielding that can damage the hose and relocate to prevent damage to the hose.
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Step 15 - Connect the remaining hose ends onto the heater core fittings using a hose clamp tool to activate the clamp.
Step 16 - It helps to activate the clamp tool before attaching the hose to the fitting. (Note: Do not use lubricant to aid hose installation as it may cause it to prematurely fail.)
Step 17 - Once the heater hose connections are complete, refill the cooling system.
Once the job is complete, and the radiator is being refilled, start the engine and allow to warm up to operating temperature (thermostat open) and top off with coolant, then reinstall the radiator cap. Once the car has been driven, check for coolant leaks and recheck the coolant reservoir fluid level.
Helpful Information
Heater hoses transfer hot engine coolant into the heater core where it's processed into warm air and utilized by the heater system. Some systems are designed with a fluid control valve which stops coolant from flowing into the core which should also be replaced with the hose set. Heater hoses should be inspected for wear and failures when inspecting other coolant hoses such as the radiator hoses. Occasionally the heater core will trap air inside (post repair) the core producing a bubbling noise which should dissipate.
Best Practices
- Always clean the hose sealing surface (fitting) to ensure a good seal.
- Replace hose clamps with new units.
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