Heater Core Bypass
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!
Can you post some photos? I think you hit a home run with this thread but...it helps members of the "all thumbs club" :rolleyes: to actually see the work. What can we say other than "way to go".
Everyone can view my photos at http://www.cleanmpg.com/photos/showg...=500&ppuser=36
Thanks for the photos as they are worth a thousand words spoken to a mechanic or the Ford garage. My only concern now is the warranty or the possible effect of this modification on the warranty. My Hybrid (same color as yours) is only 33 days old with all 3102 miles on it. Will have to check with the local Ford Dealer on this.
You have been a wonderful resource for many of us. Keep up the good work.;)
If you developed mold problems or anything with regard to the climate control system that bypassing the core caused, the warranty might be affected for that repair. The way I did the mod though, you can reversed it in ten minutes to the stock installation with the same stock hoses. I can't think of any problems that the bypass would cause. The heater pump has no circulation problems the way I returned the coolant. Coolant normally goes in the bottom and out the top of the heater core and there are no moving parts effected.
Originally Posted by billyk24
With all the cabin cooling problems in EV I've suffered in my hot weather, I would have done this the day I first drove my FEH home if I had thought it would help this much. The vent fan now feels like a fan for the first time.
Trip to Pgh
Originally Posted by GaryG
How much would you charge to take a trip down to Pittsburgh and do this for the MMH's in the 'burgh?!?!
I am a far stretch form even an amatuer mechanic so I wouldn;t even try this. But I do hate how the air gets so warm and humid in EV mode.
With Billy and your post, it looks like I should have made a step by step instruction post. It's very simple to me because I've had heater cores leak and there was no need to replace them here in South Florida. We just bypass them all the time if they go bad.
Originally Posted by Labbett Family
It's funny, the auto parts man that sold me the elbows was in shock when I mention I was modifying a hybrid. They admitted they knew nothing about hybrids and said I was on my own.
If there is interest on detailed instructions or a kit to do what I did, please post your interest. Everything is very simple and easy to get to, and the parts can be found from the information I posted. If your still at a loss, I can make a kit with the U connection and plugs. All you would need is detailed instruction to make the mod.
Today I had a good test of 91F temperature with 100% humidity. Even
though the A/C recir is much better, it was still no where near
perfect trying to drive EV max. I did do a segment for about ~9 miles
at 60mpg (with no stops) and the cabin stayed decently cool. It would
still be hard for someone sitting in the back seat though.
Running the A/C all day did take a hit on my average tank MPG. A 30
mile highway segment with a 12mph headwind with no drafting caused the
most of the damage today. Here are my Scangauge "Todays Average" readings.
4387 RPM max
184 FWT max
Today I had to go to 6 locations and the vehicle got hot sitting in
the sun while it was parked. This caused the A/C to run longer to cool
down the cabin again in the middle of the hot day. The battery did
perform better with the cabin A/C running. It will take some
relearning for me and I was trying some new things and some of them I
will not bother with anymore. One thing I was trying to do was keep
the cabin too cold.
Originally Posted by Labbett Family
With detail instructions and a kit, your favorite mechanic should be able to perform this modification while charging you less than 30 minutes of labor. This would be the easiest way for members of the "all thumbs club" to have this done.:o
I might like to have a kit if your going to make them.