Heater Core Bypass

Discussion in 'Ford Hybrids' started by GaryG, Jul 12, 2007.

  1. GaryG

    GaryG Well-Known Member

    Hi All

    Just completed a heater core bypass and what a difference it made on the A/C in EV. I've had a feeling the heater core was causing the recir air to heat up much faster for a long time, but took action today. It was easy, cheap, and took only 20-30min after I got the parts and let the engine cool down an hour with the hood up. Here is what I did:

    I couldn't find what Advanced Auto said was a kit, but I found
    two heater hose 90 degree elbows that I attached together to make a U
    shape with a 5/8" piece of heater hose. The nipples from the heater
    core were plugged with heater hose plugs that just slip on tight. I
    didn't want to leave the core open for contamination. Used the
    existing clamps to install the U bypass to the stock hoses that were
    not cut. Used tie wraps to secure the U bypass. The reason I felt a
    return was needed was mainly for the electric coolant pump. The Parts
    Supply employees said just plug the hoses, but I wanted to stay on the
    safe side and maintain a return coolant flow.

    I cut off about a 1/2" of one end of both elbows so the U would be
    closer to the distances the two heater core nipples are apart. As you
    disconnect the top hose, slide the existing clamp on the existing
    heater hose further on about 2". Have a small container below the core
    nipples to catch any coolant. As I slid the hose off, I plugged the
    core nipple with the new plug and held the end of the heater hose with
    my thumb. You can then raise the heater hose up so coolant will not
    run out and attach the pre-made U bypass with the existing clamp. Do
    the same with the bottom heater hose and the bypass can be completed
    with both hoses above the engine. Remove the pan with about 4-6oz of
    coolant that was lost before putting the bypass back in place. Add the
    coolant back to the reservoir. Tie wrap the bypass to the heater core
    nipples to secure.

    Bought two clamps, two 5/8" plugs, small piece of 5/8' heater hose,
    and two 5/8" plastic heater elbows. Total cost was ~$10.00. Access is
    real good and you can fit a small pan to catch coolant that drains
    while making each connection so the coolant can be replaced in the
    system after the installation. The work took about 20-30 minutes total
    after letting the engine cool for about an hour with the hood up.

    The heater core was responsible for losing most of the A/C cold air while in EV so fast. This is going to be a nice summer this year!

  2. GaryG

    GaryG Well-Known Member

  3. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Gary:

    ___That was a pretty darn good idea!

    ___Good Luck

  4. psyshack

    psyshack He who posts articles

    I should do this with the Civic. The fresh air vent system is near worthless in the summer time. The air is much warmer than fresh air from the windows.... IE the heater core.
  5. GaryG

    GaryG Well-Known Member

    If your feeling warmer air during the vent mode than outside air, this mod is for you. After the mod, I turned my A/C on and drove about a half mile and thought the air was cool, but should have gotten colder. Then I realized I was in EV and the compressor had not come on yet because the ICE hadn't started. Normally, the cabin would have gotten warmer with the windows up with no A/C, but the fan itself was now working like a fan and had a cooling effect for the first time.

    For those that have the FEH/MMH, the battery performs much better running the cabin A/C. Now that I can stay cool in EV in the normal A/C recir mode, my mileage should improve. With the windows up and staying cool while I push EV mode, I will improve my mileage now. Before, the normal recir A/C wouldn't last those long EV mode drives or stops, so I had to kick the ICE on or roll down the windows because of the heater core.

    The way I did the bypass, I can reverse it in about 10 minutes to the stock installation. I thought about placing valves for the bypass, but I would have had to cut the existing hoses and I didn't know how much of an effect the bypass would make.

    Thanks Wayne, I'm just mad I suffered with the heat this long, but I hope others can enjoy their vehicles more with this easy mod. Sure glad I didn't need to drain the coolant system to do the work also.

  6. DebbieKatz

    DebbieKatz ФЕХ Царйца

    Gary --

    I definitely want to see this this weekend!

    What about those of us who need heat in the winter (I don't, but my non-menopausal husband does ;)) - would this be easy to reverse for someone with 10 left thumbs? :p
  7. GaryG

    GaryG Well-Known Member

    Debbie, it's real simple and I'll show you at Hybridfest. If you want, I'll stop and get the parts to do the job there. It leaves everything to just squeeze the existing clamps back further on the hoses, remove the plugs with your fingers and plug the hoses back in. Bring a pair of pliers as that will be all you'll need.

    Also, I just did a test run with the camera mounted on a tripod behind the seat and it works great. Had to use tie wraps to hold the tripod in place. Where is your SG2 mounted? If you can put it in the center on top of the dash, we can video both the Nav screen and SG2 with a clear shot of the road ahead. If someone brings a HDTV with surround sound and HDMI port to Hybridfest, we could play the video from my camera Friday or Sat. I leave for home early Sunday. I just plugged the camera up and played my test video, and it was great. The 5.1 surround worked like a charm!

  8. GaryG

    GaryG Well-Known Member

    I'm bringing 3 heater core bypass kits with me to Hybridfest. One is for Debbie if she wants me to do it for her, and the other two are for sale for the total cost of the three kits. That would be for $20 each and if Debbie want hers installed, your welcome to watch me do the work. Just get with me ASAP to arrange the install and pick up the kit I put together.

  9. DebbieKatz

    DebbieKatz ФЕХ Царйца

    Hi Gary --

    I'll take you up on that offer :) But I want to practice changing it while you're still there, to make sure I'm doing it right. I'm not kidding about those 10 left thumbs :D

    My SG2 has been "temporarily" mounted on the dash above the NAV screen since I got it last March! :D I'm thinking I'm going to make it permanent one of these days, because it makes it so easy to show off my FE :)

    Sounds like the video will be great! Any chance of making copies?

    See you tomorrow!
  10. psyshack

    psyshack He who posts articles

    The MZ3 doesn't have the warm air problem like the civic had. So no mod needed now. :)

  11. GaryG

    GaryG Well-Known Member

    I'm at the Clarion Suites Madison Rm 308 now and about to go down to the free happy hour between 5:30-7pm here.

    The location of your SG should be great if we don't have a problem with glare. As far as copies, I think we can make a few regular DVD's, but the Blue Ray HD are ~$35 for a blank disc. My laptop can copy both, but I having a problem with the blueRay copies because of programming. Maybe one of you techies here can help me. I'm lost without my son.

  12. Nward

    Nward New Member

    HI All,

    Is there any harm in just using a shut of valve so when I need heat just turn on the valve.

    I will need the heat back as it gets cold in Kansas.
  13. GaryG

    GaryG Well-Known Member

    My concern is the electric heater pump and the flow to and from. I thought about valving also, but circulation was a big concern as well as cutting any of the stock heater hoses under warranty. You can return to the stock installation in a matter of minutes with the bypass for heater functions if need be. I just did not want to take any chances with burning up the engine or heater pump.

  14. Gary C

    Gary C Member

    GaryG, your heater bypass mod sounds like something I can do (i'm all thumbs).
    I've got the parts and i'm going to install today. I'm taking pictures and will post them
    if I can figure out the upload procedure. The mod will be done on my 08 mariner.

    Gary C
  15. Gary C

    Gary C Member

  16. Nward

    Nward New Member

    Got the bypass done.

    Also put tube insulation on the cold side of the ac lines as they did not have any.

    This did seam to make the ac in green last longer.
  17. GaryG

    GaryG Well-Known Member

    Hi Gary C

    The only things I did differently was use the existing clamps by sliding them back on the existing hoses, and then reinstalling them on the bypass. This save the expense of two clamps and I could also return the hoses back to the heater core to a stock installation. This would take less time and the dealership would never know you altered the system if you had a problem.

    Today, I did a heater core bypass on Debbie Katz's FEH while her vehicle was being displayed here at Hybridfest.

    Note, the '08 models have relocated the heater core higher on the firewall than the '05-'07 models. Everything else is the same and the bypass will work on all models.

    BTW, I maxed the Navi GPM gauge at 60mpg in the MPG Challenge with Debbie's '05 FEH. This was a ~27 mile course of city and rolling country hills. Both our trip challenges were video taped inside the vehicle and will be accessed though my article (Hypermiling The Ford Escape Hybrid) in a few weeks here on CleanMPG.

  18. Rex B

    Rex B Member

    Hate to revive a 9 year old thread, but I et im not the only one reading this with interest years later. This is a worthwhile mod especially for those of us living in the South. Right now we are at 100+ every day for two weeks.
    In the past, every car had a heater control valve which cut off hot water flow or rerouted it. It was either manual, cable, or vacuum operated. Those valves are still available. If you close off the flow entirely it is not harmful, so just splicing in a cutoff valve is the simple solution. Just open it in the Fall, close it in the Spring
    Alternately, you can get a Y- valve to divert the feed flow back to the return, bypassing the heater core.
    Very worthwhile mod. In fact I also need to do this to my 1996 truck as the blend door does not seal well. The AC is not as cold as it should be
    rhwinger, BillLin and xcel like this.

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