Replacement of Heater Control Water Valve on 2003 – 2007 Accord

The water valve to the heater core is one of the common sources of coolant leaks on the 2003 – 2007 (7th gen) Honda Accord. I had a leak that I couldn’t trace for a while as it wasn’t leaving much on the floor. I even had to rule out a head gasket leak! This is the procedure for replacing the water valve on the 7th Accord. This is an easy job!

Although this procedure is for the 7th gen accord, it’s cross-cutting on a lot of Hondas.


  • Philips screwdriver
  • 10mm wrench
  • Pliers
  • Replacement water valve (I got a used one)


1. Locate the water valve to the heater core: This is found on the firewall, directly behind the centre of the engine held by one 10mm bolt.

water valve on 2003 Accord

Location of water valve on 2003 Accord


2. Unhook the cable to the water valve: Simply slip this off with your finger.

2003 accord water valve

Cable to water valve unhooked.

3. Loosen the single 10mm bolt holding the assembly: This will allow more room to manoeuvre the part.

replacement of HVAC water valve

10mm bolt removed

4. Unhook the engine harness in the area: This will help make more room for the repair. The harness is held by 2 clips. Below shows the one to the right.

engine harness

Unhooking the engine harness. Depress tab on the green connector and pull out

5. Remove the clamp on the outlet hose: Using a set of pliers remove the clamp. 


Removing the clamp from the outlet hose

6. Remove the 2 screws attaching the valve to the metal bracket:
Removing this will make the valve free and thus make the removal of the hoses and inlet clamp easier. Furthermore, if like me you plan to reuse the metal bracket, this is the way to go. Note, if your replacement part comes with a new metal bracket you will have to make a mark on the cable to the valve before detaching it from the bracket. This will ensure proper alignment of the valve when you reconnect the cable. I did not have to detach the cable from the bracket.

Removing the bracket from the valve

Removing the bracket from the valve

7. Remove the clamp on the inlet hose and detach valve from both hoses: This step revealed the source of my leak. The inlet part of the valve was broken. Before removing the water valve, note the orientation of the part so that you do not reinstall upside down. An arrow points from right to left on both sides of the valve in the correct position.

water valve relacement on honda accord

Inlet hose removed

Water valve 2003 Accord

Water valve 2003 – 2007 Accord. The arrow shows the direction of coolant flow. This is the correct orientation for installation.

8. Install new part, top off coolant and bleed system of air: Installation is reverse of removal. For adding coolant and bleeding air you may find this previous post useful

That’s it. Done!


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.