What does the heater control valve do? (1 Viewer)

[Joe Link]

While replacing a bunch of coolant hoses I found my heater control valve was rotten, so I tossed it in the trash and ordered a new OEM valve. That order was cancelled and I had to get the truck back together, so I ran to the local parts store, grabbed a Chinese valve, and re-ordered the OEM valve. After installing the Chinese valve I realized it didn't come with the arm (which is still attached to the valve I removed, sitting in the dump). I left the valve to open so I could perform the coolant flush and check for leaks, expecting only heat from the HVAC system. To my surprise, both the heat and AC work the same as they did before I replaced the valve (both work well).

Now I'm confused, what exactly does that valve do, how, and when?

 

[Tools R Us]

It controls flow through the heaters, so when on the heater cores get hot, when off they don't.

 

[Joe Link]

So it’s not abnormal for the AC to work, it just shouldn’t work as well as if the valve were closed?

 

[ZackR]

So it’s not abnormal for the AC to work, it just shouldn’t work as well as if the valve were closed?

For the AC to work the valve needs to be closed. For the heat to work it needs to be open.

 

[Joe Link]

For the AC to work the valve needs to be closed. For the heat to work it needs to be open.

That's exactly what I thought....

 

[cahill]

So it’s not abnormal for the AC to work, it just shouldn’t work as well as if the valve were closed?

From what I understand - which isn't too much, I believe you are correct. You can have the AC on and running and still have the heater valve on. The heater control valve adjusts the temperature of air coming into the cabin by controlling the engine coolant flow to the heater cores. The AC compressor just cools and dries the air but can't cool the air enough to negate to a significant effect the heater if you want hot dry air in the cabin (ie defog the windows).

 

[shocktower]

While replacing a bunch of coolant hoses I found my heater control valve was rotten, so I tossed it in the trash and ordered a new OEM valve. That order was cancelled and I had to get the truck back together, so I ran to the local parts store, grabbed a Chinese valve, and re-ordered the OEM valve. After installing the Chinese valve I realized it didn't come with the arm (which is still attached to the valve I removed, sitting in the dump). I left the valve to open so I could perform the coolant flush and check for leaks, expecting only heat from the HVAC system. To my surprise, both the heat and AC work the same as they did before I replaced the valve (both work well).

Now I'm confused, what exactly does that valve do, how, and when?

That, was great no arm no mounting piece, I am not sure if the OEM one comes with them, good thing you live in Oregon and not the desert

 

[ZackR]

That, was great no arm no mounting piece, I am not sure if the OEM one comes with them, good thing you live in Oregon and not the desert

Just replaced mine last week, the OEM unit comes with the mounting bracket and arm.

 

[flintknapper]

From what I understand - which isn't too much, I believe you are correct. You can have the AC on and running and still have the heater valve on. The heater control valve adjusts the temperature of air coming into the cabin by controlling the engine coolant flow to the heater cores. The AC compressor just cools and dries the air but can't cool the air enough to negate to a significant effect the heater if you want hot dry air in the cabin (ie defog the windows).

^^^^^ Excellent answer.

 

[Joe Link]

Thanks for the replies, guys.

good thing you live in Oregon and not the desert

Right?? Heading down to Chemult, OR for the Gambler 500 weekend after next, I think I'm going to need it working! OEM valve should be here by then.

 

[ZackR]

Thanks for the replies, guys.



Right?? Heading down to Chemult, OR for the Gambler 500 weekend after next, I think I'm going to need it working! OEM valve should be here by then.

Are you running the cruiser in the gambler 500? Please take photos and videos if so.

 

[Joe Link]

Are you running the cruiser in the gambler 500? Please take photos and videos if so.

We built this thing, a 1992 BMW 735iL we bought for $300. We'll be mounting larger tires this weekend and finishing a few other things, but basically running it like this. I'm bringing the cruiser for support