fresh air fan bad resistor?, defrost fresh air Options

[Medtner3]

update: well, the fan was working now not even that is working. I think I might have fried the motor when I was hooking up the leads to test the fan through the resistor prongs I accidentally let the pos and neg cross ... when it rains it pours not going well today

Edited: I took my fresh air box fan out of the car and tested with a 12 V battery and it spins and works. But the resistor does not seem to work: I put 12V positive lead on the upper right pole where power comes in ( I get 11.84 volts on this terminal when the ignition was on) . ... as I understand it the other three poles are ground for the three fan speeds? So I connect each one to ground and the fan does not work

assuming I am testing correctly>>>> can you rebuild a resistor or perhaps clean it with contact cleaner and make it work again

https://forums.pelicanparts.com/porsche-911...ower-motor.html

https://forums.pelicanparts.com/porsche-914...roster-fan.html

[emerygt350]

Need some advice before I put my gas tank back in the car .

My fresh air box is not working well. The top slider does not go all the way to the left and does not go all the way to the right.

Most of all the cables in the valves on the drivers side and the passenger side valves seem very stiff and does move easily

Also, the fan does not come on. Is there a fuse for that? it's plugged in so I am guessing I need to pull the airbox and test the fan?

Have you cleaned up the top of the sliders? Often 50 years of cigarette ashes turns it into a mess. Fairly certain that is why your fan isn't working. Get some electronics cleaner, pull the ashtray and give it a good clean

[barefoot]

I'd pull the assembly out & look at the seals on the movable doors, they're probably turned to mush. Mickey (914 rubber) sells the whole rebuild kit while you're in there.

[Medtner3]

I'd pull the assembly out & look at the seals on the movable doors, they're probably turned to mush. Mickey (914 rubber) sells the whole rebuild kit while you're in there.

I already rebuilt it. stupidly forgot to test the fan while it was off, though.

I might have to pull it anyway because doesn't seem like the flaps are closing completely when the fan is in the off position

[Medtner3]

I sprayed contact cleaner on the slider on top and nothing. Does the car have to be running to work or just ignition in on position

There is 11.84 V on the plug top right which connects to the fan. Tried spinning the fan and nothing

[Medtner3]

[quote name='Medtner3' date='Jan 21 2022, 10:52 PM' post='2976512']
I took my fresh air box fan out of the car and tested with a 12 V battery and it spins and works. But the resistor does not seem to work: I put 12V positive lead on the upper right pole where power comes in ( I get 11.84 volts on this terminal when the ignition was on) . ... as I understand it the other three poles are ground for the three fan speeds? So I connect each one to ground and the fan does not work

Could someone confirm am I testing the fan correctly ... can you rebuild a resistor or perhaps clean it with contact cleaner and make it work again

[Dustin]

Resistors don't tend to fail. When they fail they burn. If a resistor fails you have a bigger problem somewhere else causing current to that resistor to be too high. Do you have a picture?

[Medtner3]

Resistors don't tend to fail. If a resistor fails you have a bigger problem somewhere else causing current to that resistor to be too high.

Okay but doesnt make sense one prong pos from battery and one neagtive/groudn to any of three other prongs to the resistor the fan should come on.

If I put pos and neg direct to the fan it was working then stopped working I may have crossed the leads and fried it I dont know

So it has to be the resistor unless there's something wrong how I am testing it

[Superhawk996]

Here is the pin out from the resistor



NOTE: disregard the Ground labeling. Somewhere I had a corrected version of this graphic but can't lay hands on it at the moment.


The fan speeds are then controlled by switching the ground path to on of the three other pins (low, med, high). See Haynes Manual for schematic.

Here are the operating parameters off my fan.

[Medtner3]

Here is the pin out from the resistor



NOTE: disregard the Ground labeling. Somewhere I had a corrected version of this graphic but can't lay hands on it at the moment.


The fan speeds are then controlled by switching the ground path to on of the three other pins (low, med, high). See Haynes Manual for schematic.

Here are the operating parameters off my fan.

that is what I had the pin that says "ground" is actually the power pin. I am frustrated dont know why the motor suddenly stopped working I must have screwed it up

I can buy a new motor on Pelican for $85 plus tax and shipping ugggh at least they are still available

[Superhawk996]

that is what I had the pin that says "ground" is actually the power pin. I am frustrated dont know why the motor suddenly stopped working I must have screwed it up

I can buy a new motor on Pelican for $85 plus tax and shipping ugggh at least they are still available

Yup - agree. Power feeds to that pin. I'm sorry for the ground reference it was a nomenclature I was using for myself meaning that it was the common connection element that the other resistors connect to.

The High setting is a straight through feel (no wire wound resistor). If it won't run on high your motor is stuck.

Not uncommon for these motors to be beyond repair. DrPhil914 and I had a thread back in January regarding trying to disassemble the motor. It really isn't possible. The bushings wear and are not designed to be serviced. Same for the motor brushes.

If you're motor is stuck or dead, just buy the URO part and don't look back.

[Medtner3]

that is what I had the pin that says "ground" is actually the power pin. I am frustrated dont know why the motor suddenly stopped working I must have screwed it up

I can buy a new motor on Pelican for $85 plus tax and shipping ugggh at least they are still available

Yup - agree. Power feeds to that pin. I'm sorry for the ground reference it was a nomenclature I was using for myself meaning that it was the common connection element that the other resistors connect to.

The High setting is a straight through feel (no wire wound resistor). If it won't run on high your motor is stuck.

Not uncommon for these motors to be beyond repair. DrPhil914 and I had a thread back in January regarding trying to disassemble the motor. It really isn't possible. The bushings wear and are not designed to be serviced. Same for the motor brushes.

If you're motor is stuck or dead, just buy the URO part and don't look back.

I will go that route, I guess mine was intermittent or already going bad. I will get a new motor then test again.

[Superhawk996]

Found the thread Drphil914 started.

Might have some info that will help you. Also has info on my motor (couldn't be fixed) and the URO replacment.

Also don't forget while you're in there, 914Rubber sells new gaskets and seals, and hardware to completely rebuild the fresh air box if you're in need.


http://www.914world.com/bbs2/index.php?sho...=351152&st=

[Medtner3]

Found the thread Drphil914 started.

Might have some info that will help you. Also has info on my motor (couldn't be fixed) and the URO replacment.

Also don't forget while you're in there, 914Rubber sells new gaskets and seals, and hardware to completely rebuild the fresh air box if you're in need.


http://www.914world.com/bbs2/index.php?sho...=351152&st=

I got all that the only thing I need is the rubber grommet where the wires go into the fresh air housing. I will definitely check out that thread . Tested my motor again this am and it briefly worked but I smell burning plastic ... not good so jerked the wires off.

I separated the motor from the fan which was very tricky used a hammer and punch and emory cloth around the impeller. Actually managed to remove the motor without breaking the fan.

the part of the motor that touches the brushes looks terrible. sanded it a little and got it to spin for a few seconds then stops.

Not wasting anymore time on this I am replacing the motor since does not really look rebuildable

[Medtner3]

Found the thread Drphil914 started.

Might have some info that will help you. Also has info on my motor (couldn't be fixed) and the URO replacment.

Also don't forget while you're in there, 914Rubber sells new gaskets and seals, and hardware to completely rebuild the fresh air box if you're in need.


http://www.914world.com/bbs2/index.php?sho...=351152&st=

I got all that the only thing I need is the rubber grommet where the wires go into the fresh air housing. I will definitely check out that thread . Tested my motor again this am and it briefly worked but I smell burning plastic ... not good so jerked the wires off.

I separated the motor from the fan which was very tricky used a hammer and punch and emory cloth around the impeller. Actually managed to remove the motor without breaking the fan.

the part of the motor that touches the brushes looks terrible. sanded it a little and got it to spin for a few seconds then stops.

Not wasting anymore time on this I am replacing the motor since does not really look rebuildable

well I figured out one of the brushes was frozen and probably why the motor was not working right. tried to get the brush out and it broke in half

[Dustin]

Did you ohm it out?

Ground is the right label for that pin.

If you have that resistor pack out of the car and a multimeter it should be pretty easy to confirm if that part is good. You can ohm it from ground to any pin and look for approximately the ohms on the chart for that pin. You can also just check continuity from ground to any pin.

[DRPHIL914]

Found the thread Drphil914 started.

Might have some info that will help you. Also has info on my motor (couldn't be fixed) and the URO replacment.

Also don't forget while you're in there, 914Rubber sells new gaskets and seals, and hardware to completely rebuild the fresh air box if you're in need.


http://www.914world.com/bbs2/index.php?sho...=351152&st=

Found the thread Drphil914 started.

Might have some info that will help you. Also has info on my motor (couldn't be fixed) and the URO replacment.

Also don't forget while you're in there, 914Rubber sells new gaskets and seals, and hardware to completely rebuild the fresh air box if you're in need.


http://www.914world.com/bbs2/index.php?sho...=351152&st=

I got all that the only thing I need is the rubber grommet where the wires go into the fresh air housing. I will definitely check out that thread . Tested my motor again this am and it briefly worked but I smell burning plastic ... not good so jerked the wires off.

I separated the motor from the fan which was very tricky used a hammer and punch and emory cloth around the impeller. Actually managed to remove the motor without breaking the fan.

the part of the motor that touches the brushes looks terrible. sanded it a little and got it to spin for a few seconds then stops.

Not wasting anymore time on this I am replacing the motor since does not really look rebuildable

Found the thread Drphil914 started.

Might have some info that will help you. Also has info on my motor (couldn't be fixed) and the URO replacment.

Also don't forget while you're in there, 914Rubber sells new gaskets and seals, and hardware to completely rebuild the fresh air box if you're in need.


http://www.914world.com/bbs2/index.php?sho...=351152&st=

I got all that the only thing I need is the rubber grommet where the wires go into the fresh air housing. I will definitely check out that thread . Tested my motor again this am and it briefly worked but I smell burning plastic ... not good so jerked the wires off.

I separated the motor from the fan which was very tricky used a hammer and punch and emory cloth around the impeller. Actually managed to remove the motor without breaking the fan.

the part of the motor that touches the brushes looks terrible. sanded it a little and got it to spin for a few seconds then stops.

Not wasting anymore time on this I am replacing the motor since does not really look rebuildable

well I figured out one of the brushes was frozen and probably why the motor was not working right. tried to get the brush out and it broke in half

(IMG:style_emoticons/default/agree.gif) lots of sellers on ebay, they are all the same, URO fan/motor assembly is what you need, its all one piece , and under $100. Drew at URO confirmed for us that it is counter balanced too, and i believe there is a one or 2 year warranty on that.
I found that on mine a previous owner had it apart and had the wires crossed in the connector, so just make sure your ground pathways for the different speeds are in the correct location. you already confirmed you have power, and your old motor was the issue. get the new seal that goes on the fan( the fan to housing seal) that is new from 914rubber, they are the only one that makes it. That will keep it from dragging and causing resistance too.
My fan works like new and i am amazed at how much air they push!.
- also get the new cables too , it makes a huge difference on the operation of the controller/sliders.

Good luck,

Phil