Heater Control Valve Question
 

YES, I know it's summer but, still...

While diagnosing a problem with my rear AC not working, I pulled the rear plenum apart. I noticed the rear heater coil was really hot even though I did not turn the heat on at all that day.

I suspect a bad heater control valve. The one that stops hot coolant from going to the core when the AC is on. I have manual temp controls so I assumen it is vacuum controlled. Alldata does not give me a loction or vacuum routing specs for the valve so I am asking here.

1) Where do I find the heater control valve? Anyone have a picture?
2) Does it shut off the coolant to both the front and rear heater cores or just the front?

Thanks!

If you have a heater control valve, you should be able to find it fairly easily in the engine compartment. Trace your heater hoses, and look for the valve. The vacuum line may have come off of it, causing your hot coil issue. One valve should shut off the flow from both front, and rear coils.

My 04 is a diesel and the valve is on the passenger side of the engine compartment, back towards the firewall, with a small grey vacuum line attached to it.

Jason, check on the passenger side. I used this to fix my 'no heat' situation, but I never did check the rear heat (just camping gear back there and it doesn't complain):-X03
Disconnect the hoses gently else get coolant everywhere and down those cops!
Sean

While you're in there scraping knuckles clean up the PCV - (pic 3 stinkin' coolant everywhere.:-X19)

What exactly do you do there?

I'm guessing you're in Anaheim, Sean.

Veggies at work, but prefer camping.





Live in Camarillo, check Trey's map (So Calif Chapter).

I was thinking "Where in So C"......

Nevermind. :-X21

Great post and pics :-X22

Thanks Sean and william_04_x. It was really obvious to find once I looked :-X19. My '04 has the electrically heated PCV so there is no heater line going to it. I just replaced the PCV last week.

The '04 in line valve is still vacuum acuated but there is actually an arm and diaphram I can watch actuate when I change from AC to heat. I moved it a couple of times manually and then tested it from the cabin switch. It moved as expected but since I disturbed it before checking it from the cabin, it could have been stuck.

I'll do some testing and check the temp of the line behind the valve to see if it is getting hot and possibly leaking past the valve. I'll also clamp the hose and see if that changes things. I'll try to post a pic of the '04 version of the valve later today.

So does the flap stop the coolant from going out the bottom of the fitting? Trying to figure out which line to put a shut off valve in...and yes I've searched and searched so this is a last resort. Thanks.

My guess is the bottom hose goes to the rear heater in the Ex. The upper left
one goes to the front passenger heater. I've never investigated this though. The one valve controls both heaters.

I was replacing this valve yearly with cheap parts; since I used a Ford part, haven't had any issue for a couple of years.

i could probably replace mine, but my ac isn't too cold, I was just hoping if I cut the coolant off to the front heater core it would improve a bit, I just don't want to put a manual valve on the wrong line.

I went/am going through this very thing. It drives me crazy that the vehicle just doesn't seem get that cool. Then the other night we were driving home at about dusk, it was still about 95 outside and I noticed the ac seemed cooler. I think we have so much surface area that the sun has a huge advantage. Now I am thinking about ceramic window tint again.

https://www.ford-trucks.com/forums/1...l#post15048442

Give your fan clutch a check, if it's not working on a hot day, that a/c will never be cold.

The heater control valve only gets vac when on "MAX A/C" any other settings it opens up. My black truck in the Texas heat takes quite a while to cool down if I don't crack the windows while parked. After a few miles on the freeway though, its blowing nice cold air. I think its just the size of the greenhouse we drive around.

mine is need of a re-tint, but I've popped the heater core box open when on max ac and that ting is red hot so I just want to keep the air blowing through the vents from starting at a 190-200* disadvantage.