Air Control Diaphragm : Anyone tried to repair it?

[visionguru]

About this thing, the hot air motor. I took it off, and tested it with a vacuum pump. According to Honda service manual, this thing should be able to hold vacuum. Clearly there is some sort of leak with this diaphragm. The result is: the hot air door never opens.
From reading previous posts, it's a common defective parts, which leave us with TWO options:
(1) Buy a new one from Honda dealer and replace it.
(2) Let it be. For folks living in warm weather, it doesn't make a big difference. But for us with very cold weather, this can be a big problem when starting up in the morning.
As far as I can understand, this "motor" is simply a rubber diaphragm (like a rubber balloon). When the air is drawn by the vacuum, it pulls the rod upward and thus pull open the air control door. When the vacuum is bled by some valve, more air comes into the diaphragm, and the rod drops, thus closes the hot air door. seems very simple. If there is any leak, it has to be the rubber that is leaking.
Has anyone tried to repair it? From what I read online, people use Plasti-Dip rubber coating to repair torn rubber diaphragms in a motor cycle, which should be very similar to this diaphragm. I am thinking of getting a can of those, and give it a try: open it, spray, and then close it. This rubber coating stuff sounds pretty useful (coat tools, water proofing metal surfaces, or even re-enforce the rubber boots, like CV boots, Ball joint boots).
What do you guys think? Any experience to share?

[A20A1]

I'm sure you can find simmilar diaphragms or uncrimp the edge of the broken diaphragm an rebuild it. Even a different diaphragm doesn't pull the door all the way up, it should be enough to start bringing in some warm air.

how are you getting that coating on the diaphragm? Are you going to spray from under the diaphragm near where the rod comes out?

[visionguru]

I'm sure you can find simmilar diaphragms or uncrimp the edge of the broken diaphragm an rebuild it. Even a different diaphragm doesn't pull the door all the way up, it should be enough to start bringing in some warm air.
how are you getting that coating on the diaphragm? Are you going to spray from under the diaphragm near where the rod comes out?

At first, I thought I could spray from rod hole while pushing it up. But if I spray too much, the rod will be seized with the metal housing. Looks like I have to open it (with pliers?).


When I apply vacuum to the diaphragm, the rod goes up about 5mm, and then drops, at the same time, the vacuum drop to 0. Looks to me, the rubber inside the diaphragm has a small crack that only leaks air when the rod moves up a little bit. I am pretty sure that if I can open it (without damaging this thing), I could easily repair it using Plasti-Dip rubber spray.


This diaphragm costs $30 (with shipping). It's not too expensive, but if I keep spending money on little things like this, it could be very costly to keep a car of this age.


I haven't got time to buy the Plasti-Dip spray yet, and we got pretty bad weather here in Chicago. For now, maybe I just stick something in and keep the hot air door 75% open at all times.


Plasti-Dip seems to be a great product. We can use it for small cracks on the rubber boots or other diaphragms. I'll keep my progress posted. Wish me luck.
Thanks.