AC mod question/idea

[WriterJWA]

Hi! I've been scanning the forum for ways to increase AC airflow to get it close to the level of the heater blower. While at speeds, the AC blower kicks out a decent volume, but when in traffic, or stopped, the flow comes out in a trickle. The design of the AC system around the blower seems to restrict air intake by forcing the air to come through the vent in front of the shifter, around the evaporator/blower housing, then through two narrow gaps on either side of the blower between the housing and the inner walls of the center console before getting to the blades.

Would it be worth cutting a hole in each side of the center console (#1 in the first photo) right over the opening in the AC evaporator/blower housing then capping the holes with grills (something like a paint-matched speaker grill), to allow for better airflow to the blower?

510323

[EuroGeorge]

I can't guarantee you will see any additional flow, but then again I sure can't see how it would hamper either.Give it a shot and report back. Keep in mind the center console is NLA from BMW. The ole rule measure twice cut once need apply.

George

[Bert Poliakoff]

Seems to me if you increase volume, you will lose airflow pressure so unless you have a bigger fan cage I think it may be a waste of time. I used to have an XJ6 Jag. They had the same problem in AZ heat. I was agble to fit in Toyota fan motors with 2" large cages. There were 2 fan motors and at that point, it moved air like crazy. I do not think there is any room in the evaporator box to do this.

[WriterJWA]

Seems to me if you increase volume, you will lose airflow pressure so unless you have a bigger fan cage I think it may be a waste of time. I used to have an XJ6 Jag. They had the same problem in AZ heat. I was agble to fit in Toyota fan motors with 2" large cages. There were 2 fan motors and at that point, it moved air like crazy. I do not think there is any room in the evaporator box to do this.

I think I understand what you're saying, but I wonder if the OE blower motor on the AC side isn't getting any air to the cages to generate enough air pressure through the evaporator and into the ducting. The reason I say that is because the heater blower motor is identical, has more access to air, and pushes a higher volume of air.

[eric1ono]

I like this idea. I've thought about the exact same thing. I remember reading where someone actually did this (either on this forum or one of the other e24 forums) and reported an improvement.

Eric

[Bert Poliakoff]

There is a fellow in texas who does all kinds of a/c installations and custom systems. I spoke to him years ago and on the early BMWs he was using Chevy evaporators.I don't remember his company. May have been hot rod air or custom air.If you google around enough you will probably find him Also try classic auto air in FLA AAh I found it Vintage Air. Don't go by their home page call them instead

[CW6er]

First make sure the center slider is closed (actually close them all). Then use the thumb wheels to open or close the upper dash vents or the center console vents to direct where you want the air to go.

One of the problems with the A/C is that the foam sealing strip between the evaporator and the upper vent ducts crumbles with age and as much air blows out into the console as comes out of the vents! There is also a foam strip on the fresh air flapper door for the center slider that can let outside air in or cold air out.

[carsnplanes]

I can't guarantee you will see any additional flow, but then again I sure can't see how it would hamper either.Give it a shot and report back. Keep in mind the center console is NLA from BMW. The ole rule measure twice cut once need apply.

George

"I cut it three times and it's still too short!"

- - - Updated - - -

Let me get this straight..you cut holes in the center console...but that brings in inside air to the blower cage. That would be the same as a "recirc" button on newer cars but inside air will fog up the windows. Normal A/C air comes from the outside so the A/C bower should be sucking air from outside normally. Only from inside when extremely hot..equivalent to the "Max" setting on newer cars. Max goes to all high settings and opens the recirc so you pull pre-cooled air to cool further, but again will fog shortly. Really need to find a way to increase the airflow path from outside to the blower.

[eric1ono]

As I understand it, the air already comes from the inside. The slats or grating or whatever you call it under the radio, in front of the shifter are where the air comes from now. But to get that air to the fan cages the air has to pass through a fairly narrow passageway which constricts the amount of air able to get to the fan cages. The OP's idea was to cut holes in the sides of the center console to allow for a more direct (and less restricted) path for the air to travel.

Let me know if I have misspoke or have something incorrect.

Eric

[WriterJWA]

I could be wrong, so please correct me if so, but the air flow through the A/C box seems to go only one direction. Looking at the attached diagram, air flows from the blower (in through the openings on each side of the housing), through the evaporator, then up into the vent system. So... It's already using cabin air in recirculation-like mode, because the blower is pulling air from the cabin via the grill behind the shifter, and shoving that air through the evaporator and into the ducting. While it would be ideal to draw air from outside, I'm not sure there is room in the system to draw air from through the firewall and into the AC blower. The only way (that I can see) to increase volume of airflow into the each cage of the AC blower, is to vent each side of the of the center console.

(Naturally, tightly sealed ducting is a must.)

510578

[1986series6]

510606I cut a 2 inch hole aligned with the center of the fan.

I used a kitchen sink drain and just painted for a close match.

I'm color blind and it looks ok to me.

Anything thicker and the glove box won't clear when opening.

The extra flow was not a perfect solution, but it really helped with better cooling.

I guess it's like a max recirculating mode.

Just realized from this photo how dusty that grill is.

And OH that ash tray is disgusting. I'll have to clean it to make my next cigar happy.

Bob V

[GazM3]

Just be careful overspeeding the evaporator fan as the faster the air goes through the coil the less drop of temperature occurs so u will have more air but it will be warmer. I'd definelty have a look at the foam and make sure the air u have is getting to the vents and not bypassing them.

Also especially if u are using 134a install a better condenser. I've got a condenser from an e34 waiting to go in which isucj bigger physically than te e28/e24 one. E34s have spectacularly cold AC when u have a heater tap that works properly.

[eric1ono]

Bob,

You are the one I was thinking of above. Glad to hear it has helped. Did you notice a change in noise level entering the cabin from the fan running?

My 2 cents, after reading threads for years on A/C upgrades, I don't think there is one mod that will change the system from mediocre to awesome (the parallel flow condenser seems to be the best bang for you buck though). It will be a number of changes that all hopefully add to the efficiency of the system and can result in an excellent A/C system as a whole.

Eric

[WriterJWA]

^^Yeah, agreed. It'll have to be a combination of things to really bring it to life. I'd really like to do the parallel flow condenser before next summer, as well as a new expansion valve and reseal the evaporator. Here over the net two months, I need to get the climate systems ready for winter before it starts getting really cold. I will probably do this mod, though.

Bob, did you have any trouble cutting the console? Any tips there.

(Note: I'm sure there are a few reading this thread chewing the inside of their cheeks away at the thought of cutting holes in the console and losing hte originality of a great car all for the sake of comfort. I feel ya... but hot is hot.;-) )

[CW6er]

....... I've got a condenser from an e34 waiting to go in which isucj bigger physically than the e28/e24 one.

Let us know what, if any, mods have to be made to get the e34 condenser to fit?

- - - Updated - - -


(Note: I'm sure there are a few reading this thread chewing the inside of their cheeks away at the thought of cutting holes in the console and losing hte originality of a great car all for the sake of comfort. I feel ya... but hot is hot.;-) )

Well, just buy a used one from the wreckers to cut up!?! :shifty :D

[1986series6]

I wear hearing aids so my radio is always turned up---what fan noise?

I think I remember cutting thru wood & vinyl.

Don't remember how I found the center of fan.

All I can tell you is that after my fix the extra

volume of cold air cooled the cabin better and it was more comfortable.

[WriterJWA]

It looks pretty good. I'm glad to see someone who has done it with success. I may be adding this to my short-term project list. Do you get better flow when at a stop?

[1986series6]

it looks pretty good. I'm glad to see someone who has done it with success. I may be adding this to my short-term project list. Do you get better flow when at a stop?

yes

[WWW89E24]

There is a fellow in texas who does all kinds of a/c installations and custom systems. I spoke to him years ago and on the early BMWs he was using Chevy evaporators.I don't remember his company. May have been hot rod air or custom air.If you google around enough you will probably find him Also try classic auto air in FLA AAh I found it Vintage Air. Don't go by their home page call them instead

The company was called European Cooler Air, Inc. and the phone number was 972-722-3791. The fellow's name is Jerry West and the site is http://europeancoolerair.com/. The site is still up, but the phone number is disconnected.Rats....I've been planning this upgrade all summer and was ready to start tearing things apart. I had long ago decided this was the best way to go. He uses a GM evaporator, bigger fan, and parallel condenser along with coating the lines somehow.

I suspect that he may have retired, though it sounded like he had a lot of work the last time I spoke with him. If I can find him, I will report back.

[eric1ono]

I just checked out the site. Too bad if he has closed up shop. Does anyone know which GM evaporator he is using? The one that said. "high-efficiency ECA unit utilizes proven GM technology to provide a super-effective alternative" on the Aftermarket Upgrades page.

Eric

[carsnplanes]

So our cars pull air in from the inside for A/C? Well I guess I didn't realize that! To me the system is already flawed. How does the cabin keep from fogging using recirculated breathing air? Isn't that the reason newer systems learned about the recirc system to direct the blower air source from inside or outside?

[WriterJWA]

Agreed, it's flawed. One fan should have been enough. I do know that recirc AC will fog the windows in the winter, or when it's cold out... but since no one is using the AC when it's cold, it shouldn't matter. I drove home today with a heat index of 90 and the AC on full blast and experienced no fogging.

I could be wrong about the system recycling air, but based on how it's designed, I don't know where else it would get air to the fans and across the evaporator and out the vents.

[Gatso7]

for some reason when you look up the address you get all these listing with real estate companies showing specs on the property. Maybe he.....white pages has him as over 65

[WriterJWA]

...another thing I'd like to do, since were in mod-land here, is put in a pair of cabin filters to clean the recycled air, as well as fresh air, without losing CFMs. That's one thing it needs.... badly.

[DanMarshall]

Agreed, it's flawed. One fan should have been enough. I do know that recirc AC will fog the windows in the winter, or when it's cold out... but since no one is using the AC when it's cold, it shouldn't matter. I drove home today with a heat index of 90 and the AC on full blast and experienced no fogging.

I could be wrong about the system recycling air, but based on how it's designed, I don't know where else it would get air to the fans and across the evaporator and out the vents.
Maybe it's because the A/C dehumidifies the air it is processing. Air conditioning was first invented by Willis H. Carrier as a dehumidification system in 1902. The way an air conditioner works to remove moisture from the air is when the air passes over the evaporator coils, the air condenses and the moisture separates from the air. This condensate is collected by a pan and drainage system which is why you will see water dripping underneath your car on a hot day.

In extreme humidity the A/C system on your car may not be enough to keep up with it however but it will have some effect. Now it will dehumidify the air faster (particularly in cold weather) if the recirculating feature is turned off but since that is not an option on the E24, it’s kind of irrelevant…
There are also the "Flow through" vents under the rear window which probably helps as well.

Dan M.

[av8r4aa]

I did probably the best, most involved AC overhaul possible.
every AC component came out and was reworked.

I installed a parallel flow condenser, Sanden compressor, sealed every possible leak.
The car is light years from stock performance.
However, the car still is no where near the new cars AC systems.
I also felt that the side vents would help the airflow. I never did install them.
I did make a big mistake in installing the fresh air/ heater blower motor in the AC box.
With just direct 12 volts the blower was awesome, if used in a lesser speed, the flow was
weak. I was happy with all the work I did, but was also dissapointed that it wasnt bone chilling cold.

I did learn that the (now NLA) parallel flow condenser was the biggest gain in the system.
If I were to do the job over, I would find a larger parallel flow condenser to use.

[eric1ono]

Can you expand a bit on the mistake you think you made? You put the heater motor and cage fans, or just the motor, in the AC box?
May I ask why you decided to do this in the first place? Just trying to understand the thought process behind the original decision.
What are the differences between the 2 motors (and cage fans if you used them)?

BTW, I agree your AC work is an inspiration for us all. It's on my list of things to do when I am willing to park the car for a more extended period of time. Collecting parts right now.

Thanks,

Eric

[av8r4aa]

I used a fresh air blower motor with standard AC cages.
I did an informal "CFM" test and felt the fresh air had more power.

In actuality, it does when on full blast. But when the blower switch is slowed,
then the force reduces quickly.

I thought we were experiencing a low flow problem with the AC.
The fresh air blower has more power flow.
At least it seems that way.
I felt more powerful blower would help the flow and cooling.
The electronics of the "dimmer" (fan speed selector)don't agree with the heater fan installed
in the AC box.

Good idea that didn't work out.

[markiehd]

I am thinking of doing several mods.... Parallel condensor up front, new sandon compressor, evaporator valve. Cleanthe evaporatar, reseal theduct work, then fix my squirrel cage.... I like the idea of increasing airflow thru side vents. Im almost ready to pull the trigger Any words of encouragement


mark

[av8r4aa]

Buy new expansion valve(s)
Clean every pipe to operating room clean.
Buy a lower threshold aux fan sensor.

Have fun