1. for access to Ford Explorer and Ranger owner generated reviews and discussion, tech tips, how to articles, off-road modifications, events, and more! Since 1996 we have been the #1 Ford Explorer resource on the Internet. We also cover the Explorer Sport Trac, Mercury Mountaineer, Lincoln Navigator, Mazda Navajo, Mazda Pickups, and the Aerostar.

    Register Today It's free! This box will disappear once registered!

Heater Control Valve 101 Please

Discussion in 'Explorer, Ranger, A/C & Heater systems HVAC' started by kware1, August 15, 2013.

  • Searches ExplorerForum.com
    1. kware1

      kware1 Active Member

      Joined:
      March 14, 2008
      Messages:
      129
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Boston, MA
      Year and Model:
      2002 Eddie Bauer
      Hi. I had an engine swap recently. I went with the lowest price for the install and now I find myself trouble shooting everything he either broke or didn't reconnect.

      Anyway, since its starting to get cool in the mornings, I notice the heat on the passenger side blows cold air. When I first start my commute, everything is normal, but then about 20 minutes in, the passenger side starts blowing cold air.

      I'm wondering what position is the heater control valve supposed to be in. Right now, I'd looking at it from the passenger side front tire, The control arm is to the right or toward the front of the car.

      if you pull off the small vacuum line that attaches, there is no vacuum that I can feel.

      My question is should that vacuum be strong that I can feel it on my finger or is there really no vacuum?

      The other is what position should that valve be in if inn calling for heat. Should the pressure of the coolant be enough to push it to the other position? It seems like that little arm should move.

      Any insight will help. Thanks.
       
    2. Support EF


      Join the Elite Explorers for $20 a year

      Explorer Forum has probably saved you that much already, and will continue to save you money as you learn how to diagnose and fix problems yourself, and learn which modifications work without having to experiment on your own. Elite Explorer members see practically no ads, add your own profile photo, upload photo attachments directly to your posts and Media Gallery, create more private Conversations, and more. Join Today. Your support is greatly appreciated.



      to hide adverts.
    3. hasoan

      hasoan New Member

      Joined:
      September 17, 2009
      Messages:
      33
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Westerville, Ohio
      Year and Model:
      1996 Ford Explorer XLT 4L
      Just the passenger side? does that model have dual zone climate control? or do you mean it is blowing hot, then gets cold? Does it happen at a time like when you get on the highway and start going faster?

      That I can't answer

      You won't feel a vaccum if the heat is in the on position (in my 96 anyway.) Try turning the air completely off and see if it sucks. Also, sorry for this question, but is the car running when you put your finger on the vaccum connection?

      Again I am not sure about position on yours, but no the coolant will not push it open. perhaps a tiny bit of coolant gets by the valve as pressure fluctuates, but then the pressure is the same on both sides again, you see?

      anyway, try running the car with the selector in every position possible, and if its like mine, it should close the valve and have a vaccum in the OFF and MAX AC positions.
       
    4. kware1

      kware1 Active Member

      Joined:
      March 14, 2008
      Messages:
      129
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Boston, MA
      Year and Model:
      2002 Eddie Bauer
      Yes I do have the dual climate control. if I put the passenger side on 90, highest setting, it will blow heat. If I turn it down at all it just blows cold air. if I take it out of dual climate, the passenger side blows cold. both sides will blow heat if it's set to the max. whenever I checked for vacuum the heat was on and the car was running lol.
       
    5. hasoan

      hasoan New Member

      Joined:
      September 17, 2009
      Messages:
      33
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Westerville, Ohio
      Year and Model:
      1996 Ford Explorer XLT 4L
      Well then, I was suspecting a possible failure of the electronic climate control, and I don't know anything about that. Hopefully someone else might.
       
    6. kware1

      kware1 Active Member

      Joined:
      March 14, 2008
      Messages:
      129
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Boston, MA
      Year and Model:
      2002 Eddie Bauer
      Thanks, but is there anything in the engine compartment I could look at? I had a rebuilt installed recently, and I've been finding little things they never reconnected. ( evap tube, a.c. plug, ambient temp probe, windshield cleaner, etc.) So, the heat worked fine before, now it doesn't. I want to isolate anything in the engine compartment that might not had been hooked up.

      Thanks
       
    7. hasoan

      hasoan New Member

      Joined:
      September 17, 2009
      Messages:
      33
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Westerville, Ohio
      Year and Model:
      1996 Ford Explorer XLT 4L
      There's also the option of going back to the people who did your engine and seeing if they can figure out what they messed up. For a job like that a few missed wires happens sometimes. I am guessing you don't want to do that unless you have to though.

      Did they have the dashboard off at all? I know they would if they were messing with the heater core or evaporator. I know you probably don't want to open that up just yet, but maybe check the connectors you can see under there too, if you haven't already.

      I am getting the feeling from what you said about the evap tube that you don't have working air conditioning. Is that true? If so, perhaps automatic climate control needs the AC to work properly for air blending. Its just a thought, and I hope someone else can tell you about that. My haynes manual only goes to 2001.
       
    8. kware1

      kware1 Active Member

      Joined:
      March 14, 2008
      Messages:
      129
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Boston, MA
      Year and Model:
      2002 Eddie Bauer
      you're exactly right. I don't want to bring it back. lol. first of all everything that I told them about, they said maybe it was always like that. so I really don't want them fiddling around off they don't even know themselves.

      as far as the a.c. and the evap, I found those myself and corrected it. so he's, I do have a.c. and no, they didn't do anything with the heater core or dash.

      I just don't have an understanding of how the system works, hence I was thinking the coolant pushed the valve open.

      I just don't have an understanding how the system works, hence I was thinking the coolant opened the valve.
       
    9. hasoan

      hasoan New Member

      Joined:
      September 17, 2009
      Messages:
      33
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Westerville, Ohio
      Year and Model:
      1996 Ford Explorer XLT 4L
      well, no the coolant will not push it open. well, should not. that i can tell you from experience. i had an overheating issue. anyway, the valve in (my, at least) heater control valve is not like a flap, it's like a switch. any pressure will go either way through it and doesnt really care if its opened or closed. there is not really much pressure actually, as the cooling system is designed for flow, not pressure. so if its clogged or otherwise blocked somewhere, coolant just doesn't flow as much. The thermostat is supposed to be responsible for the majority of the flow, and that contradicts you saying it works fine initially. so to be honest i think it sounds more like an electrical problem in your case. (dual climate zones malfunctioning.)

      Anyway, if you want to check the HCV, just switch the thing to all possible positions (cooling, heat, defrost, off, etc) and watch to see if the arm moves. that might not solve your problem, but will answer your initial question.
      Code:
                        /--< from heater core
      to water pump  <--X--> to heater core
      from engine    >--/ 
      That "X" represents what a heater control vavles positions can be. it pivots on the center of the "X". that is a very crude drawing, but the point is that it will flow either way, and the vaccum line has no trouble changing it's direction. i hope that makes sense.

      EDIT: one last detail:
      so if the valve is "open":
      Code:
                        /--< from heater core
      to water pump  <--/--> to heater core
      from engine    >--/ 
      ande if it's closed:
      Code:
                        /--< from heater core
      to water pump  <--\--> to heater core
      from engine    >--/ 
       
      Last edited: August 26, 2013
    10. hasoan

      hasoan New Member

      Joined:
      September 17, 2009
      Messages:
      33
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Westerville, Ohio
      Year and Model:
      1996 Ford Explorer XLT 4L
      Also... I am basing this off you saying its only the passenger side. If you had a partially clogged heater core, then it would make sense if ALL heat dropped when the thermostat opened. The thermostat to radiator hose is much bigger and not related at all to the heater core or HCV
       
    11. kware1

      kware1 Active Member

      Joined:
      March 14, 2008
      Messages:
      129
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Boston, MA
      Year and Model:
      2002 Eddie Bauer
      ok. Yes, that's the type of info I'm looking for. So, if the valve doesn't move at all any position, then I either have no vacuum or a bad hcv? If it does move, then maybe something in the electrical?

      Thanks for your time
       
    12. hasoan

      hasoan New Member

      Joined:
      September 17, 2009
      Messages:
      33
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Westerville, Ohio
      Year and Model:
      1996 Ford Explorer XLT 4L
      Sorry it took me a while to answer your original question :)

      That's about right, but it could be something else too of course. BTW, you should also be able to push the little lever on the HCV from one position to the other with your finger. I believe there's a spring that makes it default to open, but the vaccum closes it (if its working.) Tthats how the 96 works anyway. if there is no vaccum going to the valve, follow the line and check for disconnects or pinches. there's also a couple vaccum harnesses under the dashboard, and behind the climate control panel.

      However, I think as you mentioned before that there may be a temperature sensor somewhere not working.

      That being said, I looked up a picture of your HCV on autozone's website, and it IS different than mine. Mine has 4 connections, and yours only has 2 it seems. Therefore my diagram is incorrect. In that case, you may be right about it being possible to be forced open by pressure. I'm not sure. But then when the thermostat opens up, no more forced open valve. I think I get your reasoning now. sorry if I misled you.

      Doesn't anyone else on here have a Gen 3? lol.
       
    13. kware1

      kware1 Active Member

      Joined:
      March 14, 2008
      Messages:
      129
      Likes Received:
      0
      Trophy Points:
      0
      City, State:
      Boston, MA
      Year and Model:
      2002 Eddie Bauer
      yes, the valve does spring back. I was thinking it defaulted closed then when the engine reached temperature, if opened to provide heat. that was just a guess on my part. but you have some things to look for. thanks.
       

    Share This Page








    We Support Our Troops!