Cat 257B2 A/C noise,vibration

[Dug1973]

Good evening. Question about the A/C on my cat skidsteer. The air conditioner works, or at least blows a little cooler air than outside temp. But when you turn it on it runs normal and quite for a bit, then it starts making a “rumbling “? Noise, sounds like it’s coming from under the seat. I also notice when I turn ac switch on, the left joystick will move ever so slightly. So before I raise the cab I was curious what I should be looking for. Thanks

 

[Nige]

Have you tried disassembling the A/C ducting and giving it a good clean..? Have the A/C filters been replaced..?
A S/No would also assist. Is it an SLK-prefix machine..?

 

[heymccall]

Compressor is hydraulically driven. That's why you don't see a compressor when you open the back door.

 

[Dug1973]

Yes it is a SLK machine. And I was curious if it was a hydraulic compressor. But why would it make that sound? All other hydraulics function normally

 

[heymccall]

Do both condenser fans work?
My compressor would chug when the high side pressure climbed too high due to fan(s) failure.

 

[Dug1973]

Ok neither condenser fan works. Keeps blowing the fuse. I blew both fans out, full of dirt, so I’ll get new fuses and see what happens tomorrow. If o need to access the fans what’s the process?

 

[heymccall]

On my 248B (same condenser setup), I tilted the hydro tank forward, after raising and securing the cab.
Then, a bunch of fasteners. Including IIRC unmounting the condenser itself.

What I would do is, instead of undoing the shroud and condenser, I'd break or cut the fans at or near the mounting bolts (4 per fan). Then you can put a wrench inside the shroud to unbolt the 4, per fan, m6 nuts. Now, instead of nut and bolting them back like OEM (where the nuts required the shroud to be off) acquire 8 U nuts (fender nuts), slighty enlarge the 6mm holes so the u nuts latch on, then rebolt the new fans in.

 

[heymccall]

218-6250 is the p/n for a fan (2 required).
My cat dealer is $193 ea.
Aftermarket also offer the fan. It's just a 12v 10 blade SPAL fan. Like below.

 

[92U 3406]

I've rarely seen a B series unit with both fans working. They always seem to jam up or seize up.

 

[heymccall]

I've rarely seen a B series unit with both fans working. They always seem to jam up or seize up.

Hence the reason for u nuts. I've changed them on my 248B several times.

 

[heymccall]

Oh, forgot parts page image.

 

[Dug1973]

Thanks for all the help, I do appreciate it. Looks like a little shop time in my future!

 

[Dug1973]

One more question where can I find a owners manual for this machine? SLK08447. Manuals I’m seeing the serial number does not go that high. Seems like I can’t find parts for a 257B2. Are all B series the same?

 

[Nige]

I can help you there. You can download a manual in pdf form from Cat Publications.
Go to - https://catpublications.com/
When the popup appears click on "Continue as Guest"
Put SEBU8386 in the box and click Search. You should see the illustration below. $49 for a pdf download. If you want a CD or paper version there will be S&H charges to pay on top of the price.

 

[Dug1973]

Thank you, very helpful. Look forward to being part of the site.