Heater valve
So how does the coolant flow through this? When closed it goes in the front and down the bypass. But my question is when it is open, should it flow both down the bypass and into the heater core? Because that is what mine is doing.

I figured I'd pull it while the coolant was drained and check it since my heat was weak.


Edit-I posted a pic but for some reason my pics dont show up?? Maybe it's a need to be approved thing?

 

My 03' has a vacuum operated shut off in the heater hose that is supposed to, if I understand correctly, close only when Max AC is selected. When I didn't have heat last winter, I found that the PO had zip tied it shut. I also had a blend door issue which is probably why they had the valve tied shut. Does yours switch to cold air readily when you change the temp control? Any clicking or clattering from behind the glove box door? If you have a noise like that, your heat issue may be a blend door actuator. Not sure about the pics...they usually go up seamlessly. Edit: After looking at this post, https://www.ford-trucks.com/forums/1...rear-heat.html , I think yours has a different setup than mine.

 

Thanks for the info. It definitely could be a blend door. Haven't gotten that far yet. Just trying to figure out if the valve is working first.

My valve has 3 ports. Hot coolant in, bypass out and heater core out.

The flow on mine after I pulled it and manually tested it was full flow out bypass and closed to heater core or split flow out of both bypass and heater core. Cant recall which one was with vacuum applied.

 

Makes you wonder if it shouldn't switch completely over to the heater core instead of splitting the flow. I don't know but maybe one of those who do will see this and shed some light on it. I would assume that all the Excursions and trucks that don't have ATC are set up like yours.

 

It definitely makes me wonder that. I'm going to find out soon if that is how its supposed to work as I ordered a new one from Rock Auto last night. 😊

 

To answer the question for any future searches....the new Motorcraft valve performed exactly the same way as my old valve. That is no vacuum applied equates to flow to both bypass and heater core outputs. Vacuum applied flow goes to bypass exclusively.

 

You keep saying "bypass", but I think the valve is just a heater shutoff valve which stops the flow of coolant to the heater cores.
A three port valve will shutoff coolant flow between the inlet port and the two output ports.
One of the output ports goes to the dash heater core and the other output port goes to the heater core in the rear of the car.
A vehicle with only a front heater will have a two port valve.

 

I'm sorry if I offended you with my incorrect "terminology!" . I'm still learning my way around the Excursion.

The valve however is never completely shut off. It always flows out what I was calling the bypass or the nipple on the bottom which you stated flows to the rear heater core. When vacuum is applied it flows only to the rear. With no vacuum it flows to both. So it only shuts off flow to the front core if that is where the bottom (what I called bypass) goes.

I guess I had incorrectly assumed the two hoses on the bottom radiator hose were to and from the rear heater but it wouldn't make sense as that is not the hottest coolant. One must be the front heater core return and the other the rear heater core return. On my 94 suburban with rear heat the supply and return were right next to each other so I incorrectly assumed it was the same on the Excursion.

 

I wasn't offended, just trying to get on the same page about how that valve works.
The output port for my rear heater core is on the bottom of the valve.
The vacuum activated valve is a butterfly valve at the top of the assembly that I thought shuts off all flow thru the valve.
Maybe the rear heater core and AC do not share a chamber and coolant is always running thru the rear heater core.
I'll have to check that tomorrow with the IR temp gun.
Does the new Motorcraft valve not completely shut off flow?

 

I know, I was just teasing and being dramatic about being offended.

Correct, the new Motorcraft valve never shuts flow off completely. It behaves exactly the same as the valve that was on my Ex. No vacuum equals flow out of both bottom and rear port. Vacuum applied equals non flow out of rear and flow out of the bottom.