Home made
(Edit: Since the following post, I made another adapter that has three tubes rather than two. They fit fine by staggering them slightly.)
Okay, this is probably over-kill. I've heard many times that keeping avionics cool is a key to their longevity. Avionics aren't cheap as we all know.
Here's how I made my own blower:
The blower is a Sunon 97mm System Blower Fan. $21 from these folks
http://www.fanwholesale.com/sunon-97mm-blower-p-59.html
Mouse & Digikey have the same thing I believe.
It's brushless & has ball bearings. Puts out about 30CFM.
I made an adapter out of .020, traced out the opening, added tabs on each side that will allow it to fit over the blower opening. The blower opening measures 1-1/4"x2-1/4".
Before I bent the tabs, I located the hole centers. The holes need to be 5/8" dia.(since the Garmin stuff has 5/8 ports on the back for air inlets) I drilled the holes using a unibit. Bend the tabs down after the holes are drilled & check for fit on the blower.
I cut the 5/8"OD tubing to about 1-1/4" long & used my flaring tool to flare one end of each piece.
Mix up some JB-Weld or some sort of epoxy and apply a bead on the OD of each tube at the flare. Insert the tube from the inside of the adapter and align each tube to be perpendicular to the face of the adapter. Let the epoxy cure & paint to match.
Slip the finished adapter over the blower opening, drill two holes for screws through the tabs and into the plastic blower housing on each long side.
I originally made the adapter with two tubes but saw that it could have had three if spaced properly. I have a 430w & 327 and may pipe the third one over to the lightspeed box. EDIT: I did in fact, make a three tube configuration. Worked great!!
As I mentioned, the fan puts out 30cfm. I know I've choked it down some but it may still be blowing too much. (a 430w only requires 1cfm) So I may need to come up with a speed controller. (anybody got any ideas on that?)
I actually think you could use use one of these blowers to pump some air to you while taxing on a hot summer day....for the tipper folks anyway...