alohart
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Re: Condenser Damage - 2015 BMW i3 REX

Sun Mar 24, 2019 2:13 pm

I have considered attaching some stainless steel woven wire mesh directly to the back side of the black plastic grill whose openings are ~3" x 25". However, the heat exchanger is considerably larger. Maybe the total area of its openings is no greater than the total area of the grill openings such that the grill openings provide more airflow than the heat exchanger can pass at higher speeds. If wire mesh were attached to the back side of the grill, airflow through the grill would be reduced, maybe enough that the heat exchanger would not receive enough airflow to operate efficiently in the hottest weather. Maybe the cooling fan could compensate for this reduced airflow, but I would prefer not to change the behavior of the cooling system. However, if a larger piece of wire mesh were mounted between the grill and the heat exchanger, the mesh might not restrict airflow if its open area is large enough.

Another possibility would be to cut out the closed section of the grill above its top horizontal rib and mount a 4" x 25" piece of wire mesh directly to the back of the grill. The additional airflow due to the greater grill open area might compensate for the reduced airflow of the wire mesh. Mounting the mesh directly on the rear of the grill would make removing leaves and other debris easier.

Thoughts? Suggestions?

A leaf is currently lodged against the heat exchanger in our i3. I've never paid attention to this area. I might be able to dislodge the leaf with a stream of water. However, the area behind the grill is sealed, so the leaf would have to come out through the grill. If a water stream doesn't work, I might be able to fish the leaf out with a long screwdriver, coat hanger, etc.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

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MKH
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Re: Condenser Damage - 2015 BMW i3 REX

Mon Mar 25, 2019 5:33 am

Art

In talking to an engineer friend who works with high-end building and equipment AC/ventilation systems, he said that you can (very) roughly estimate air flow reduction of mesh, by taking the surface area that is 'blocked' and subtracting 10%. For example mesh with 50% surface area, and 50% open area would, on average, show a 40% reduction in air flow, 60% open area, 30% air flow reduction.. He also said that reducing air flow to the open grill with a mesh barrier shouldn't be a big deal. He said that the engineering rule is that you always over-engineer components by a factor of 50%. So if an AC system is designed to work in 100 degree + heat in stop and go traffic with limited air movement - considering the normal 50% over-build factor, a mesh grill shouldn't have a much impact on AC operation unless you start getting down to gnat-size protection window-screens.

I ended up ordering a new 'screen' from these guys, as the stainless mesh I ordered to experiment with seemed just too fine:
https://www.customcargrills.com/

This one:
https://www.ebay.com/itm/CCG-UNIVERSAL- ... ctupt=true

Once I get it, going to look at how easy it is to drop the plastic drag-reduction skid panel under the front of the car, for easier installation access behind the plastic grill (and to remove several leaves :P )
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 20 inch wheels, EVoInnovate EVSE

kallisti5
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Re: Condenser Damage - 2015 BMW i3 REX

Mon Mar 25, 2019 6:57 am

The hardware cloth worked wonders.
It really looks best if you install it with the bumper off... which I admit is a pain for such a modification.

I cut out a section and formed it to the inner side of the bumper's air intake. Then I primed it with self etch and pained it black (to hide it a bit better). Took the thin wire wrapping the hardware cloth and used it to tie it to the plastic bumper pieces.

I purposely left the sides open and covered ~90% of the opening (centered) to not restrict all the airflow (but looking at this thread that may not have been needed.

Overall it looks great (if you stoop down and look under the bumper), and I'm pretty sure I won't have this issue happen again :-)

Image
Image
(yes, one of the intake clips are on the wrong side of the bumper there... my desire to have it "perfect" is offset by the work to disconnect the 100 screws holding the bumper panel on :-)

Only downside is you'll need to check it once and a while to make sure it doesn't get blocked by leaves, etc.

alohart
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Re: Condenser Damage - 2015 BMW i3 REX

Mon Mar 25, 2019 11:17 am

Thanks for your informative post!
kallisti5 wrote:The hardware cloth worked wonders.
It really looks best if you install it with the bumper off... which I admit is a pain for such a modification.
Is it not possible to install the hardware cloth from above or below without removing the bumper?
kallisti5 wrote:Only downside is you'll need to check it once and a while to make sure it doesn't get blocked by leaves, etc.
I view this as an advantage because debris that is trapped by the hardware cloth would instead end up potentially blocking the heat exchanger where it is more difficult to remove.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

alohart
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Re: Condenser Damage - 2015 BMW i3 REX

Mon Mar 25, 2019 12:28 pm

MKH wrote:In talking to an engineer friend who works with high-end building and equipment AC/ventilation systems, he said that you can (very) roughly estimate air flow reduction of mesh, by taking the surface area that is 'blocked' and subtracting 10%.
That's good to know. Thanks!
MKH wrote:Once I get it, going to look at how easy it is to drop the plastic drag-reduction skid panel under the front of the car, for easier installation access behind the plastic grill (and to remove several leaves :P )
It looks like 10 screws plus an unspecified number of latch mechanisms. I worry about breaking these plastic latch mechanisms.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

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MKH
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Re: Condenser Damage - 2015 BMW i3 REX

Tue Mar 26, 2019 3:51 am

Hi Art
I worry about breaking these plastic latch mechanisms.
I agree on that front lower bumper piece - danger of breaking some of the latch things.

The piece I was thinking of taking off is this piece, which looks to be just held in with screws, and should just drop down, which would give access to the grill from underneath/behind.

https://www.newtis.info/tisv2/a/en/i01- ... 1VnXyQrtvl

Another alternative is to use a paper pattern to accurately cut the mesh to fit in front of the grill opening, edge the grill with rubber trim:
https://www.customcargrills.com/Grill-Trim.asp

...and install it in front of the opening.
https://www.youtube.com/watch?v=dls_a5O6KkE
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 20 inch wheels, EVoInnovate EVSE

kallisti5
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Re: AC Condenser Damage - 2015 BMW i3 REX

Wed Mar 27, 2019 7:00 pm

A quick side note, i've been keeping those steps updated with how to change the condenser + charge the system.
The AC oil was a horrible mess since BMW is all over the place on what to use. Let me know if anything looks wrong.. I spent way too much time trying to decode what BMW wanted me to use :P

The car is making 38F air, and the compressor quieted down quite a bit once I injected the oil. Time will tell, but results are positive so far.

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MKH
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Re: AC Condenser Damage - 2015 BMW i3 REX

Mon Apr 01, 2019 9:36 am

Found that dropping the plastic skid plate under the front of the car does NOT give any access to the rear of the grill area, :(

But I have figured out how to mount the grill mesh I bought right behind the grill, without doing any dismantling of any part of the front of the car what-so-ever. A little fiddly, and time-consuming, but easily do-able. Will post pics and how-to in the Modifications/Accessories section when I get a chance.
After 2 r.jpg
After 2 r.jpg (71.57 KiB) Viewed 138 times
Mark H.
2015 i3 Rex, Capparis White, Tera World, Technology & Driving Assistant, Parking Assistant, Harman Kardon Audio System, 20 inch wheels, EVoInnovate EVSE

alohart
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Re: AC Condenser Damage - 2015 BMW i3 REX

Mon Apr 01, 2019 4:16 pm

MKH wrote:Found that dropping the plastic skid plate under the front of the car does NOT give any access to the rear of the grill area, :(
That's too bad. During my brief examination, it appeared that this panel was a bit too far to the rear to provide the needed a access.
MKH wrote:But I have figured out how to mount the grill mesh I bought right behind the grill, without doing any dismantling of any part of the front of the car what-so-ever. A little fiddly, and time-consuming, but easily do-able. Will post pics and how-to in the Modifications/Accessories section when I get a chance.
I have my #5 stainless steel woven wire mesh (74% open area) and look forward to reading your installation instructions.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

Star63
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Re: AC Condenser Damage - 2015 BMW i3 REX

Tue Apr 02, 2019 10:32 am

I removed the bottom "lip" first. After that it was easy to remove the grill. About an hour for the whole job.
Not bad - but MKH´s method sounds still way easier :roll:

I used painted aluminum screen mesh.

Image
2014 BMW i3 REX

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