928er

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Rob Edwards

Never read about anyone modding or changing the fan. If anything in both my cars, I think the blower fan moves plenty of air, but there is an excessive amount of air movement noise thru the vents when the blower is on 3 or 4. More CFM out of the fan would just make that worse, no?

In many of my cars there is some inverse relationship between the fan speed and the perceived 'coldness' of the air blowing, as if the evaporator can only remove so many calories of heat from the passing air if it's moving fast. Would a blower that goes to '5' necessarily improve heat transfer from the air to the refrigerant, thus cooling the car faster? I don't know the answer to this.

I ASSume you're asking because you'd like more rapid cooling now that your A/C works? How clean is your evaporator?

danglerb

Maybe the thing to do is improve the ducting to increase the air flow?

Fan on the dash trucker style might help.

Dave928S

Fan design has changed over the years so that you can move more air efficiently, and more quietly.
I deal with a large commercial manufacturer of fans (all they make is fans and ducts) and it's amazing the progress in fan blade design and efficiency over the years, and the advances in duct acoustics. Generally noise means turbulence, pressure drop and inefficiency.

I'd guess that you could get higher volume and quieter flow just with improvements in fan and duct design. I don't see much in the way of good air flow design in vehicle HVAC systems ... they seem to be just made to fit in a confined space and connect the points .. and that's all.

Putting in a faster motor or more blades could just make it sound like an F15 taking off.

danglerb

Could be they were designed noisy so people would know they were working. It was middle 70's before Porsche seemed to catch on that in the US we want AC.

Imo000

Is your evaporator clean? When they are clogged, the airflow is significantly cut as if the fan is not pushing enough air.

Also, just as said above, if the evaporator/heater core can only handle so much, a larger fan will actually reduce the heat transfer capacity (AC will become warmer and heating becomes cooler).

finally!

I noticed a few weeks back while it was very humid and AC blew some fog that the center vents blow a lot of air through the areas above, in between and below the vents themeslves. Went on the hunt at the local Lowes and found some weatherstrip, I think the below is the image of it from the Lowes site.

It is white and is made to form a V with 1/2 of its width having a thin adhesive on it. I cut four pieces the width of the vents themselves and put on the offending areas of the vents themselves. For the space in between the two center vents I used two pieces of it, attaching one piece to the other to make a W shape then attached to the bottom vent so either vent could be moved up and down. Painted the pieces black after testing and installed.

Seems to have improved air flow as well.

Tampa 928s

You need to Pm Zeus he had modded his center vent and increased air flow significantly.
Maybe he will chime in from what he told me it is now adjustable for both passenger and driver and blows like a hurricane.

finally!

Searched for posts by Zeus but no luck.. anyone have the link to the above?

Curious...

SeanR

With everything working correctly (actuators, cleaned evaporator, etc) the air should blow your hair around from the center vent.

Fabio421

https://rennlist.com/forums/members/45017-zeus-.html

Brent

Here you go Mark, Paul just did this for me last week. Split the vents to left and right as apposed to all left or all right. It really does make a difference. No more giving my wife all the air from the top vent. Paul did remove the flap behind his vents, but I keep mine.

SeanR

That's a great idea Brent, can you shoot a pic of the back side for us?

Brent

Not my idea Sean, all the credit goes to Paul (Zeus). I'm just another grateful recipient of this 928 community. I'll take some pictures of the back side of the vents and post them soon.

Brent

This is kind of funny. I was going to post a picture on the random picture thread and see if anyone could tell what's wrong with the pic. Oh well, I'm going to do it anyway.

So, the horizontal articulating track is cut on both sides of the center vertical piece. Removing two small pieces of the horizontal track, per vent. Do not cut too close to the vertical pin where it passes through the horizontal track. The center vertical piece is glued into place at the pin site. Paul used some type of silicone so it was easy to trim and could be completely removed if necessary.

Hope that make sense.