Interesting Article on AC flow improvement

[Phattey]

Don't know if folks have seen this, and I hope I'm not violating any Copy Rights from the PCA website, but here goes...Not sure what year car he's talking about. But if it'll help on my '87 I'll try it.

This is a cut and paste..

This is not a question, but a tip for all those who, like myself, live in areas where decent air conditioning is not only desired, but a necessity. I find that the problem with the a/c in these older 911's may not necessarily be a higher than normal discharge temp, but low airflow at the dashboard registers. There is a floor discharge outlet right in front of the console that discharges cold air from the evaporator and diffuses it straight out onto the front seat occupant's calves. The problem with this set-up is that A: This air is coming directly from the evaporator housing and is at its coldest, so your legs get the coldest air while your upper torso and head feel the heat and humidity, and B: This vent acts like giant leak in the system, causing a large pressure drop downline at the dash registers. The result of this is low flow at the dash registers. To remedy this, I removed the diffuser, made a plug from a trimmed plastic spray paint can cap, pushed it into the duct, then re-installed the diffuser to keep it from popping out. I now have much better airflow at the dash registers, making my car much more enjoyable to drive on hot days, with no permanent modifications to the a/c system and at very minimal cost and effort.Please pass this on to other members.

[Hugh R]

Also, if you look at where the a/c air return is below the passenger floor board, that is a terrible location. My return has a flapper door on it to keep dirt out. I removed the flapper door, 2 screws, and took the floor board and mat out and improved flow a lot. I may make a new floor board with a hole cut in it, and a similar hole in the floor mat to improve the return air flow.

[scottb]

What you're describing is the theory behind Griffith's Kuehl Vent. It takes the cold air that would otherwise cool your legs, and brings it out into the cabin. I have one, and it's a nice improvement.

[preeble]

I thought that cold air only came from the dash vents? Does cold air also come out the floor vents as well? If so, is it configurable?

[Andras]

No, not from the floor vents, but from the "butterfly" behind the gear shift.

Look behind there (you might need to use a flashlight, since it's dark down there), and you will see a plastic piece shaped like a butterfly. This can be removed with two screws, and then the air flow will be directly at you chest, hence improving your AC.

[RickM]

This has been discussed in the past. The offending part is commonly referred to as the "Bowtie"

Some merely remove while others install a Griffith's/Performance Aire vent system or fab one up from junk yard components.

Here's a link with pics. In this thread there is a reference (and another link) to Don Plumleys pictoral. Any new A/C Center Vent / Bow Tie removal projects completed?

[Phattey]

Hmmm...

I must be crazy...it appears my "bowtie" seems to have 2 openings to it. One seems to blow air out, at my calves - while the other feels like it is drawing air in...kinda like its a return thing...

What am I missing here...I thought the bowtie threw air out to the passenger and drivers legs. Mine seems to be just driver side with what appears to be an intake on the passenger side.

Sorry for being a Dumb@ss....I just gotta' know...

Phattey

[Hugh R]

I have an a/c system that is apparently an Italian design (not very good either). Its a ROW car and deesn't have a bowtie, just solid sheet metal. My system blows fresh air out the windshield and vents under the dash, but not the dash ones. My a/c blows through the windshield, dash and underside of dash vents.

[jgporsche]

Seems like a good idea. I will try that tonight. Thanks!

[88911coupe]

I just pulled the bowtie off and left it open...sounds like I have probably screwed this up. I'll just block it off since I want more air coming out of the vents.
Also, on a related note, has anyone got any suggestions on how to increase fan capacity? Are there better, aftermarket fans available to fit in the smugglers box area?

[DonMo]

I found a simple solution. The Kuehl vent is really no different than any dash vent. I went on ebay and found a adjustable center vent, used a rubber connection piece that I found at your local Lowe's and used the two screws under the ash tray to mount it and voila. Fifteen dollars and I have adjustable air.