A/C blower switch & 3d scanner and printer anybody have?

So Ordering a Air Con blower switch from the usuals i discover that the switch they sell after reading posts in this forum is the positions are different. I believe it’s the same switch we use in some of our AC units in the boat industry that I can pick up for about 15 bucks. I have one of those and I’m using it temporarily. I disassembled the OEM Ranko switch. And discovered the plastic cams basically get melted from the Excess heat on spring contacts , Went to much current is being drawn through them.
I’m working on a Diagram to use a single three output relay to go to blower and resistor. Thus taking the load off the wiring through the switch. Bottom line is if somebody has the ability to scan these plastic cams and we could remake them a lot of the image image image Oem Ranco switches can be rebuilt. Let me know if anybody is interested and I will send them the plastic cams to scan.

Probably easier to manually model than try and scan with consumer technologies.

What is the cam made of? What temperature and forces is it subject to?

If you model one (try tinkercad) I can print you one.

Im guessing its nylon by the feel and hardness. Its just subjected to the tension contact spring. Heat is an issue in its current wiring design , like the headlight switches they are running the load thru the switch. So the raised follower on the contact spring melts into the cam.
Hence why Im going to reconfigure mine to have the switch just control relay.
Ill give that program a try. Ive never done but always wanted to delve into. These should be relatively easy to measure.

Tinkercad is super easy.

I’d have guessed nylon is the proper material here. I can print in nylon but never have. I believe I have a sample spool that I could try. Abs or PETG may be other options that are more readily printable.

Let me know, happy to try nylon :slight_smile:

I’d have guessed something like Bakelite would be better, but I’m certainly not a materials engineer. Besides the material degrading, the problem I have is burned points. And it’s a lot of work to go in and dress the points to get the switch to work again. I guess the manufacturer didn’t expect the same switch to be in use 50 years later, so the system was designed for low cost, not infinite life. That’s why I bypassed the original switch and added a rheostat to control the blower.

Edit: There’s been a lot of progress in plastics during the last 50 years, maybe a plastic like Ultem would be appropriate. The trick is cost effectively manufacturing a limited number of pieces from it.


If you have an undamaged part, it would be quite easy to use to make a silicone rubber mold, then simply cast new parts using a suitable plastic casting material. No special tools or experience necessary.

All the information and materials needed to do it are available here:

Ray L.

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I was thinking of what can be printed on a desktop 3D printer. There are some exotic materials available but Nylon is probably the sweet spot.

yes the issue is at least with my switch, the raise portion where the contact arm rides on the cam has melted indents into it. you can see them in the picture. Getting the base measurements of each piece should be easy in Tinkercad, but ill have to really learn quick how to create the stepped cam portion. lol

An hour with some needle files and a small hacksaw and you can make one from whatever insulating material you choose, like some high temperature plastic.