Rickg, That is a good one !

Cool, thanks!

What's the difference between "shielded" and "sealed"?

I presume that only one's needed...

The sealed bearings have a seal like your wheel bearings have. A moisture and dust proof flexable seal. Shielded have thin sheet-metal type "shields". They'll only protect from dirt and low-flying birds from getting in. Better than what's in the fan now, which is "open". They have they're balls hanging out in the open .
I used sealed for the longevity. But I'm hoping the extra turning friction won't cause the motor to draw too much extra amperage, which won't be a good thing either. If in doubt, go for the shieled and dunk them in a can of clean oil before using. They should already have oil in them, but just to make sure. Wipe em off good as you can and put em in.

__________________
past MB rides:
'68 220D
'68 220D(another one)
'67 230
'84 SD
Current rides:
'06 Lexus RX330
'93 Ford F-250
'96 Corvette
'99 Polaris 700 RMK sled
2011 Polaris Assault
'86 Yamaha TT350(good 'ol thumper)

So when I pulled the fan apart one of the brush holders was completely burnt up. I mean melted down one side almost to the point that it was completely gone.

I took the old brush, wrapped it in plastic (ziplock style) and then formed a new side for the brush holder out of JB weld... God I love that stuff!

Got a brush that with some major modifications (cut in half, then filed a lot) was made to fit the holder.

Mounted it all up and tested it on the bench and things were looking good. Tried to test it last week with the AC on and making the run up to MT B but couldn't get it to start running even with the car at about 95 degrees indicated. So I gave up...

It has been until today that it has been hot enough again to try it and the darn thing wouldn't turn on. No power even when I short across the thermo switch on the dryer. Been thinking and thinking what could it be???!!!
Duh, start with the simple things... Fuse was blown.
OK, so I replaced the fuse and now with the AC on when the car hits about 82 on the gauge the fan kicks in. Screaming more than my old Piper Cherokee used to do at full throttle but that's another story...

So now the fan runs but the fan does not seem to want to turn off once it is running. If I shut the car down for 15 minutes after all is cool then restart the car the fan does not come on but if I shut off the AC and just let the car idle once the fan is running it just keeps on blowing. The temp is down below 80 or at least it's stabilized on the thermostat cuz it has never run that cool before.

Anyway, this does not seem normal and in my mind points to the thermo switch on the AC system as a possible failure point. If this switch is bad it might also explain why the brush holder got hot enough to melt but I could be wrong...

Is this normal operation that even after the car has cooled but is still running, it does not shut off or do you think I have a bad switch? Turns on but just won't turn off.

Your input as always is greatly appreciated.

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique

Okay, I'll simplify this post.

The aux fan comes on as expected. After turning off the A/C though it does not shutoff, even when the car is registering a colder temp than it normally runs at.

Only after turing off the key adn letting it set for at least 15 minutes then it does not come back on.

Is this normal?

__________________
'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique