Fresh Air Blower Rebuild - Resistor Switch

[scottjk]

I'm rebuilding my fresh air blower from a 1983 SC. Upon disassembly I found one of the wires on the resistance spring assembly snapped. What do you guys recommend? Can it be fixed? Is there a replacement only part?

I've seen a guy install a digital control switch to the A/C fan assembly. Probably could retrofit a digital control for the fresh air motor but unsure at this point.

Also... what are the two wire springs attached to the fan blades? I'm assuming for some type of balance but it seems odd.

Finally... digging through the parts catalog I can't find replacements for the two rubber baffles inside the blower unit that regulate fresh air flow. Mine are cracked and I'm unable to completely shut fresh air off.

[Anjizkit]

Following.


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[CBA]

me too

[sparkysvega]

I bought these seals on 914rubber.com.
https://914rubber.com/flapper-valve-seals-in-blower-housing-1

[Dr J]

Originally Posted by scottjk

I'm rebuilding my fresh air blower from a 1983 SC. Upon disassembly I found one of the wires on the resistance spring assembly snapped. What do you guys recommend? Can it be fixed? Is there a replacement only part?

I've seen a guy install a digital control switch to the A/C fan assembly. Probably could retrofit a digital control for the fresh air motor but unsure at this point.

Also... what are the two wire springs attached to the fan blades? I'm assuming for some type of balance but it seems odd.

Finally... digging through the parts catalog I can't find replacements for the two rubber baffles inside the blower unit that regulate fresh air flow. Mine are cracked and I'm unable to completely shut fresh air off.

I would replace it with a more modern controller. Those springs are high current resistors. They put it at the entrance to the ac inlet to cool it down which, ironically, heats the air going into the AC. It just wastes current. You can try something like this:

https://griffiths.com/porsche/air-conditioning/911-930/porsche-911-930-climate-controls/

I believe the springs on the fan vanes are for balance.

For the rubber baffles, there is the one source listed above or… have a mousepad somewhere you can cut up?

[PeteKz]

Agree with what Dr J said. I don't like the foam rubber seals. The foam wears, compresses and deteriorates over time. Even though the original ones lasted a long time, after market foam parts tend to have about a 10-12 year life span and then they crack and fall apart.

Instead, I cut up some old inner tube into the correct shape donuts. I cut them a little oversize at first and them trimmed them to fit snugly. Works great, and I didn't have to wait for new seals to show up. Whatever rubber inner tubes are made of seems to last a very long time.

[wazzz]

Originally Posted by Dr J

I would replace it with a more modern controller. Those springs are high current resistors. They put it at the entrance to the ac inlet to cool it down which, ironically, heats the air going into the AC. It just wastes current. You can try something like this:

https://griffiths.com/porsche/air-conditioning/911-930/porsche-911-930-climate-controls/

I believe the springs on the fan vanes are for balance.

For the rubber baffles, there is the one source listed above or… have a mousepad somewhere you can cut up?

Yes you could replace this with a more modern controller, like the one from Griffiths, but it is designed for the AC blower and is controlled by a rotating pot that replaces the 4 position rotary switch. Quite an easy fit since they are both rotary controls.
On the other hand, the fresh air blower is controlled by a 4 position linear lever switch that is not so easy to match to the pot of a PWM controller, whether from Griffiths or from China. You would have to replace the pot with several fix resistors and control them with the lever switch positions. A bit of work.
Or you can stick to the old technology and reattach the spring resistor by whatever means. Also clean the blades underneath and make sure they are free to move and make contact when they heat. These are thermal blades made to protect the resistors by temporarily shorting them if they heat up to much. Ancient technology.

[targa80]

Originally Posted by wazzz

Yes you could replace this with a more modern controller, like the one from Griffiths, ………
On the other hand, the fresh air blower is controlled by a 4 position linear lever switch that is not so easy to match to the pot of a PWM controller, whether from Griffiths or from China……..
Or you can stick to the old technology and reattach the spring resistor by whatever means. ………..

I agree with wazzz, reattach the wire wound resistor to the post so the fresh air slider will operate as it was designed. Having a modern electronic fan speed controller that has the capability of taking the fresh air slider three speed input lines to control the fan speed would be nice.

[Dr J]

The way I solved this issue is unfortunately not available today. As part of my self-redesigned ac system, I purchased an evaporator fan motor from a company called retroaire which seems to be defunct. The motor had an extra tap and connected to the stock switch. The resistor pack was no longer needed and it did not use PWM tech. It energized part of the motor coil depending on the switch to provide the speed setting. To this day it works great. I hardly ever take it off the lowest setting.

Interestingly enough, my voltage regulator went out and the way I knew something was off was the fact that the evaporator fan was blowing really hard, particularly as I increased rpms.