Ventilating System no blow!, What am I missing? Options

[jsaum]

I'm trying to get everything working on my 72 914 including the fresh air blower and defroster control on the dash. I traced down the power going to the control selector lever for the three speeds, the red & white wire which does have 12 volts but it doesn't connect to anything! Am I missing a connector or a wiring harness that gets power to the blower motor from the dash? There isn't any bulbs or holders for the red and blue bezels on the control panel it seems like there should be more there!

Thanks for the help!

Jsaum

[BeatNavy]

I tore into my '72 fan housing too look at the resistors and other connections. Here's a picture of the resistor springs. When I measure the resistance across each, I got something from 4K to 8K ohms (the multimeter bounced around).



Here are the corresponding 4 posts on the outside. One, I think the upper right, is the 12v input. The others are ground connections that connect from the climate control grounds in the dash through these resistors and to the ground connection at the actual blower motor.



With the blower in the housing I was able to "bench test" it on the battery by connecting a 12v jumper to the upper right connection and then use a ground wire at the other connections. I found I had something like a slow speed when I grouned the right lower pole and a high speed when I grounded the lower left pole. Not sure how I was supposed to get a mid speed.

Then I hooked it up to the connector under the hood. Here's where the fun started. I get a little smoke when I put the climate control selector on low, a LOT of smoke when I put it on mid speed, and good, solid blower action (and no smoke) on high. Obviously I'm shorting something to cause the smoke. I'm not sure what gives. Need to think this through some more. Smoke near the fuel tank is not an ideal feature.

[BeatNavy]

I tore into my '72 fan housing too look at the resistors and other connections. Here's a picture of the resistor springs. When I measure the resistance across each, I got something from 4K to 8K ohms (the multimeter bounced around).



Here are the corresponding 4 posts on the outside. One, I think the upper right, is the 12v input. The others are ground connections that connect from the climate control grounds in the dash through these resistors and to the ground connection at the actual blower motor.



With the blower in the housing I was able to "bench test" it on the battery by connecting a 12v jumper to the upper right connection and then use a ground wire at the other connections. I found I had something like a slow speed when I grouned the right lower pole and a high speed when I grounded the lower left pole. Not sure how I was supposed to get a mid speed.

Then I hooked it up to the connector under the hood. Here's where the fun started. I get a little smoke when I put the climate control selector on low, a LOT of smoke when I put it on mid speed, and good, solid blower action (and no smoke) on high. Obviously I'm shorting something to cause the smoke. I'm not sure what gives. Need to think this through some more. Smoke near the fuel tank is not an ideal feature.

So I did some more testing, and it appears that I'm only actually getting smoke on the low setting. By explanation, of the four pictures in the post above, the upper right pole is the power input. The upper left is the low setting ground. The lower one opposite, just under the power pole, is medium. And the lower left one is high. At the connector in the trunk, the power line is always hot, and moving the fan speed select switch grounds one of the three poles - upper left for slow, lower right for mid, and lower left for high speed.

Clay Perrine helped me figure some of this out, like the fact that I guess the low speed actually grounds through both of the resistors while the mid only grounds through the bottom. The fan moving helps cool the resistors. Right now I'm getting smoke on the low setting and the fan is not moving. I can see that the fan may not be lubricated or moving freely enough to move on the low setting. So do I most like a) have a short there that's causing the smoke, or b) is it just the resistor(s) overheating without any fan action to cool them?

I'm ok without any low fan if I have mid and high at this point, so if I'm risking anything I can just snip the low resistor, I suppose.