You didn't need a separate switch, lifting one of the heating control levers just enough to start he blower would suffice.

Pelican Technical Article: 911 Cooling Boost

The switch can be placed anywhere in the high side, IIRC Porsche once used one, screw-in stud type, attached to R/D.

Looked up SSI heat exchangers and I must say I'm puzzled, how does the engine shroud fan blow air through your SSI heat exchangers?

Plus, what about the heat control module function that helps to cool down the engine using the cabin heat blower?

++, Isn't it unwise to run the footwell blowers without the cabin heat blower creating positive pressure in/at the flapper valves?

You are correct, Mr. West. The SSI's are basically copies of 1972 911 heat exchangers, made in stainless steel. They eliminate the catalytic converter, and use the 72-style muffler. The main engine cooling fan is connected to the SSI's by duct pieces from older pre-electric blower cars. I, myself, just use the electric blower as a suction fan that pulls air through the condenser and blows it out the engine tin. You are correct, this arrangement eliminates the additional cooling function, but the fan would be on anyway. There is also a theoretical chance of sucking exhaust gases into the cabin at very low engine RPM's. In reality the foot well blowers don't pull all that well compared to the engine fan.
These mods are part of the heat back date process. It simplifies the system and does eliminate certain of the later models' features. For better or worse.
Dave

I simply mounted the fan to the condenser by pushing fins aside and running a bolt right through and using a fender washer on the non-fan side.

You're so smart!
Great idea. I always do things the hard way.
Thanks,
Dave

Last we heard your retroaire system was not quite up to snuff, had to rev-up the engine at times, have you made more improvements?

I don't remember complaining but I'm OK with the system. It's not fantastic but it does the job - never great when stuck in traffic. The fan and the sealing described above seem to have helped in that situation. Not certain it's ever going to be good enough for my wife in the San Antonio summer but it's a whole lot better than nothing.

My latest project (a backdated 83) has a single 964 condenser mounted in the front left fender with a 10" fan pulling air through air ducted from grills in the front facia but otherwise the same set up. I'll report on how it works out

Interesting, Laurence. I could not find a way to fit the condenser in the front wheel well of my 84. I was willing to pull the washer bottle,, overflow tank and even the fog light, but still I could not make it fit. I would love to see some details.
Thanks,
Dave

I just want to clarify. My Retroaire system works great in steady state performance. I get mid 30 to 40 degree vent temps in 90-95 degree weather. My problem is dealing with heat soak. My car is typically 140 degrees inside, and it take 15 minutes for the vent temps to drop into the 40's. I typically have a 20 minute drive home, so I am hot for most of the way. Once the system catches up, it seems to work just fine.
I will recheck my T & P's once the weather warms up, and report all, with and without fans.
Take care,
Dave

I didnt have any major issue. ill take photos when i have it up the lift. I couldnt fit the factory mounts or fan so I used a flat 10" fan i bought on ebay but the condenser itself fit with no problem. Mine is angled in the same way a 996/986 radiator might be (probably about 60 degrees from straight) and with help of neoprene and aluminium I have enclosed it so that one end of my centre oil cooler hole (I used a shorter oil cooler), my horn grill (remembering the car is backdated) and an extra opening cut into the bumper below the horn grill all feed around and into the front of the condenser. The fan is mounted behind the condenser and sucks air into the wheel well. Photos wil make this a little clearer. As I said earlier I havent tried it yet but I'll let you know.

Just ocuured to me that one other tyhing that may make a major difference is that, because my car is a backdate, I was able to remove the front bumper mounts. Probably couldnt have done it without doing so. That may be the key.

It is great you are going to put to the test the theories of Wwest. That is the true measure of any theory. Please report back you finding once it gets hot. Good work!

Nice little mod!

"Heat Soak" quick cool-down procedure, not that you don't already know, just covering the bases.

a) Max A/C.. of course.

b) Windows down 1/2"

c) Fresh air blower ON.

b, c, long enough to remove the HOT cabin atmosphere, maybe even for a slightly extended period to somewhat cool down the cabin interior surfaces.

Almost a shame we can't reverse the A/C airflow route to help move the HOT air up and out!

What about a Trinary switch? Did i miss that?

See post #18...SmileWavy

I have a brand new Trinary switch that I purchase but, never installed it. If any of you AC experimental types want it let me know via PM and I will send it to you for free. It is a Red Dot which I believe wwest is using. It also includes the plug coupler which makes it easier to wire in to the system.

I actually purchased two thermostatic switches that clip onto the discharge pipe from the compressor (1/2"). I selected 130 and 120 degrees, to choose which to turn on the auxiliary fans. I don't have them yet, but I don't have any hot weather yet either. One of those switches plus my binary switch should be the equivalent of a trinary.
Again I will report when hotter.
Thanks,
Dave

What about a Trinary switch? Did i miss that?

Dick,
See post before. The response crossed the question in cyberspace,
Dave