Advice on vibrating a/c condenser fan

[badwater]

Happy fathers day!
I'm looking for some expertise on a very noisy front a/c condenser fan. A few things that we can eliminate:

1. The blower motor is new.
2. The squirrel cage fan appears to be undamaged - at least nothing visible.
3. I did put a few drops of lube on the fan shaft bushing
4. When I open up the housing and jump the leads to the fan motor, it can spin without vibrating, but eventually vibrates with no obvious change to the inputs.
5. There are a number of balance clips on the fan body, and I didn't find any extras in the housing, so there's no obvious reason for the fan to be out of balance. I kinda suspect that the fan is out of balance though.

Any way, let me know if you guys have any ideas. The A/C is still operating well, but the sound is at the very least unpleasant - kinda like driving my 911 around in a very large dentist office.

Thanks! Dave

[DRACO A5OG]

You do mean the evaporator blower fan, Yes? The one in the smugglers box or the one at the front belly section?

[kuehl]

Take the condenser motor and fan out of its housing.
Carefully secure it in a holding device, ie. a vise gripping the lower section (opposite wheel shaft end) ... don't squeeze it too much or you can deform the motor case.

Use a dial indicator mounted on a base and place the probe on indicator on the top of the blower wheel near the outer diameter. Carefully rotate the blower wheel until you find its highest point on the indicator, note this point with a pencil mark.
Carefully bend pull up on the opposite side (180 degrees across) of the wheel just few 1/16ths or so of an inch.

Rotate the wheel 360 degrees and check to see if the 'bend' corrected the difference. You are attempting to get the top of the wheel running flat as possible.

Be careful how much you bend the wheel, the center metal bushing where the motor shaft slides into is peened onto the top of the blower wheel.

After you have corrected any wobble carefully insert the assembly back on the plastic case and test it under power.

[badwater]

Draco, it's the condenser motor - next to battery, pushes fresh air through the front pan condenser. Thanks, Dave

[Discseven]

+1 on Kuehl's input. I had same with evap blower. Squirrel cage was out of square.

[badwater]

thanks for the advice guys. will get the blower out again this weekend and see if I can find the high spot! -dave

[badwater]

Gang, just sending out a follow up note. Per Charlie's suggestion, the blower was out of square and out of round. It was pretty easy to find the high spots and low spots and apply finger pressure to address those.

However, once we connected the straightened blower to power, it was still significantly out of balance. We used a crayon to gently find the high spots (i.e. heavy spots) on the spinning fan and started adjusting the balance weights until the fan could spin smoothly. It was about 2-3 hours of work, but the blower fan is running quietly now.

Full disclosure, I've built and trued lots of bicycle wheels over the years, so finding and adjusting high spots on a round electric fan was not too hard for me. Balancing a spinning fan? That was new.

Thanks to all for the suggestions, and I will do everything in my power to protect the squirrel cage fan from harm in the future...

[john walker's workshop]

Fuse that thing before it burns up your car.

[badwater]

right!

[86 911 Targa]

Originally Posted by badwater

right!

^^^^^
As John just posted, install one of these.




^^^^^
Before you have one of these.................

Good luck,

Gerry