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blang311 · 01-14-2021, 01:01 PM

So our air conditioner compressor froze up snapped the serpentine belt. On a I SL9 Cummins 400. Mechanic came replace the compressor and now issaying that the serpentine belt that he matched up with the old one for length is the wrong size. How could that be possible anybody ever run into this we are stuck on the side of the road

96 Wideglide · 01-14-2021, 01:12 PM

No number on the old belt?

That's what I used when I bought a replacement.

Cincy Steve · 01-14-2021, 01:14 PM

Freightliner chassis? They can email/text the correct belt number w/picture of the routing!

Jorgem2 · 01-14-2021, 05:40 PM

Make sure they are routing it correctly. Also, follow the diagram for that motor.
“Matching” a serpentine belt visually is difficult. It’s best to go by the part number on the old one if it’s visible.
Best of luck.

blang311 · 01-14-2021, 08:30 PM

So the part number was not visible, freight liner didn’t know the belt but did send the diagram. It was the same one I had. The tech was not experienced with rv repair and it was looking bleak. He finally went and came back with a handful of belts. He bypassed the new compressor and we were ready to leave, 7 hours and a lot of money later.

Solo_RV_Guy · 01-14-2021, 08:40 PM

Added to the "to do list" if purchasing a new coach: Pics of all belt/hose part numbers and pics of belt routing.

Sorry to hear of the additional expense and inconvenience, but if it helps, I've learned from your experience. Thanks for posting.

veraken · 01-15-2021, 05:28 AM

Get your ESN (engine serial number) and go to https://quickserve.cummins.com/info/index.html Register your vehicle. It's a great source for info on replacement parts. You can also call Cummins Customer Service ( 1-800-286-6467) and give them your ESN

This will tell you where your ESN is: https://www.dieselpartsdirect.com/fi...-serial-number

triplewide · 01-15-2021, 05:58 AM

Can you tell if the compressor is installed in the same position as the original? Did the new compressor mounts match the original?

sledhead · 01-15-2021, 06:07 AM

Not sure, but different coach builders may use different compressor manufacturers with different size pulleys and mounting, that could make a difference in belt length.

Gary RVRoamer · 01-15-2021, 08:58 AM

It seems evident that your mechanice didn't match the size correctly or the new compressor was installed in a different position. This isn't rocket science, but it does require meticulous attention to detail.

Cummins can't help - they didn't install the engine and add compressors or belts. Freightliner Custom Chassis shipped the chassis with the compressor in place, but without the compressor working. The coach builder hooks up the compressor to the dash a/c and does the final belt adjustments.

bpu699 · 01-15-2021, 01:03 PM

This is one reason I plan to carry extra belts with me when I travel...

blang311 · 01-16-2021, 06:19 PM

Thanks everyone, I can’t tell if the compressor is exactly the same because he took the old one with him as a core return. To make matters worse he could not get the AC hoses off the compressor so he cut the lines. I think it is going to be a challenge to get it all back working when we get home.

Skip426 · 01-16-2021, 06:49 PM

Sorry to hear about your problems .

But , every Cummins diesel pusher , I've seen; heard of ; up till now, the dash A/C compressor , wasn't driven by the serpentine belt .
The serpentine belt , drives the fan hub ( idler in case of side rad ) and a V belt from the fan hub , drives the compressor. As per pictures below.
The V belt ( yellow arrow) can break and damage the serpentine belt.( green arrow)
But because the alternator and water pump are driven by the serpentine belt , a quick replacement of the serpentine belt , will get the coach mobile ; without touching the A/C compressor .
If your belt routing is different than these pictures . I'd love to see a photo.

Roy-c · 01-17-2021, 06:30 AM

Your problem is the Tech that you had was inexperienced and in way over his head. Cutting the hoses is just plain inexcusable. At this point your only option is to go to a place that has experience with your vehicle and have the repairs done properly. Perhaps you can recover some $ from the first company. It is a shame that people on the road are at the mercy of these boobs.