8 cylinder front engine iconic vehicle
  • User avatar
  • User avatar
  • User avatar
User avatar
By ChrisZ
#154214
Well, after getting the AC system perfectly balanced with R134a for the next couple of years I drove to SITM and promptly had problems.

First issue was an hour in when the AC died. Blew warm, 96 degrees outside, yuck. Pulled over and rather than pull the climate unit to see what was up with the darn relay I just bypassed the AC compressor at my external relay under the hood (years ago I rewired so the climate relay would only engage a second 20a relay under the hood by the expansion valve and THAT would be the thing to power the AC clutch). Used a 7.5a fuse to do the bypass and AC is working!

However I also bypassed the freeze switch so I had to run the front blower full blast. Worse things happen so off I went in total comfort. Right up to Banner Elk when the blower started to seize up.

Great.

Decided not to pull the blower at SITM instead I pulled the AC control unit, popped the top off the relay, cleaned the contacts with 1000 grit sandpaper and sure enough everything is working again. Since the relay is only switching 200ma instead of a very inductive 5a load it should last forever.

However blower was still not happy. So I drove home with the rear AC on full blast and that seemed to do it. Had to turn on the front AC from time to time to keep the front evaporator from freezing up and the fan was very loud and unhappy and only ran at full speed.

Once home I pulled the fan. Doing so isn't bad, as someone mentioned you just take off one side of the roof, hold it CAREFULLY and pull out the unit. Oddly enough the inside bolt was NOT present, weird.

With the fan off I opened the box, took out the fan, and tapped off the fan cage with a drift. I could see the problem, the lower bearing had seized to the shaft and made a mess out of the bearing housing. Ah well, time to fix the motor.

You can take these motors apart. The secret is to use the right size chisel right where the front motor bracket is hooked to the main body. Tap gently and work the sides out of the slots around the peening. Then once off pull the bearing off the darn shaft (another drift against the axle with the bearing supported in a vise) then clean up the armature shaft on the wire wheel. Get it nice and happy and shiny and the bearing will slide on again.

Then it's grease, get the bearing back in the cage, tap down the sides of the cage to hold it again, use a locking pliers to compress the peened sides of the main motor assembly, then tap in the front motor bracket and re-peen the motor sides. It makes sense when you do it.

Fired it up, put fewer washers on the front and got the motor spinning happily with one washer and the circlip. Figured I'd try 2 washers so I popped off the circlip, put it down, put the washers on, couldn't find the circlip. Motor was also jamming in one direction.

Yep, magnets picked up the circlip and sucked it between the magnets and armature. FUCK! Well have to take off the BACK of the motor.

Same basic idea except you need to pull back the brushes to take off the armature and do NOT PULL THE ARMATURE OUT BY THE REAR BRACKET! PUSH THE FRONT OF THE ARMATURE SHAFT FROM THE FRONT OF THE MOTOR, NEVER PULL FROM THE BACK. The armature is held in the magnetic field and will rip the brush holders apart.

Yep, there was the circlip. Oi.

Anyway with the back off I pulled the armature out of the rear bearing (pull back on the brushes first), greased the rear bearing, then put everything back together. Motor ran at 13.7 volts, 3 amps with no load which isn't bad.

Then I put it together, put the cage fan back on the shaft, put it back into the housing, fired it up, tore up the housing a bit because the fan was too low, pulled it apart, tapped the fan further up, put it together and everything WORKS!

Fan is back in the car but it's dark so I will test it tomorrow. The brushes were about 50% used so I will probably have to replace them in 20 years. Will try to remember that.

Overall the electric motors in these cars are pretty serviceable. Go slowly, never try to force or yank at things, and take your time. I could have bought a $200 used motor on Ebay but it probably would have needed a rebuild as well, and could have had a seized bearing as well....

Picture of the motor apart.
Image

Image

Image

Image
Hey_Allen, MFranke liked this
User avatar
By worf
#154276
Interesting.
User avatar
By ChrisZ
#154356
Installed. Good news, the fan is blowing nicely at full blast. Bit of a vibration, could be that I haven't screwed it down or that the front bearing is going to vibrate a bit. Could be a problem, will see how it goes.

Bad news: Speeds 1,2,3 do nothing. Which means the resistor pack probably has burned contacts from trying to run a shorted fan at lower speeds where it could not turn. Out comes the fan again to pull the resistor pack....
User avatar
By Mrmerlin
#154363
Chris you dont remove the fan to remove the resistor pack. just push the duct boot out of the way ,
use a wire to fish it out,
put a towel under the duct so you dont loose the screws.

and i would call Roger and buy a complete new fan motor for your car its slight modding and then its a drop in order a new long screw as well
MFranke liked this
User avatar
By ChrisZ
#154388
Oh, Rog has a new fan motor? I may just get that and keep it in reserve for when/if this one blows up again. I'm curious to see how long the repair lasts.

If you have an original fan motor it's pretty simple to disassemble it, clean the armature up, and re-grease the bearings. Almost a PM type of activity and after 30 years they all probably need to be overhauled (like the window motors.)

Proper repair would be to insert a sealed ball bearing in there, that fan on the end puts a lot of stress on the lower bearing assembly. Then again as someone said at SITM: After 30 years greases pretty much become glue regardless.

Meantime swapped out the resistor pack, one of the resistors had opened. Have a spare so not a big issue. Now fan runs properly at every speed even super low... Let's see if the fan pulls 20a then I should be able to calculate the wattage values for replacement resistors....

Image
MFranke liked this
User avatar
By ChrisZ
#160759
Yeah, the jammed motor bearing basically toasted it.

That said I swapped in a new motor from Roger ($200 or so) and it looks pretty good: Same as the old motor, balanced, works fine. While I had the motor and housing out again I took a vacuum and cleaned under the fan unit. That spot right in front of the fan had an INSANE amount of junk washed in there. Leaves, sticks, dirt, had to knock it out with a long screwdriver then vacuum it up.

Hopefully it didn't rust under there but I'd say pulling that fan every few years and cleaning under there is pretty darn critical.
By MFranke
#162365
In case it could help anyone, or for the more visually oriented, I made 3 videos showing these procedures. 1st is removal from and reinstallation in the car.; 2nd is bench removal and replacement of the motor from the blower housing; and 3rd is bench repair of the original motor, with new brushes and a new commutator.


User avatar
By ChrisZ
#164129
That's really helpful: I didn't need to take the whole hood off, just the one side while removing/installing then leaving the bolts in otherwise to keep the hood from blowing away. Makes re-aligning it a good bit easier.

Working like a charm! God I love AC when it's 95+ outside.
MFranke liked this

Thank you, that is good information on Hammer's gr[…]

VIN look up?

Roger can do it Monday when he’s home. We[…]

Oil Sender

Will you be at Frenzy?

GTS Brake Ugrade

I call them shims;) You could also call them dam[…]