ac compressor belt jumping off

NHbalerman · Sep 18, 2020

I just got this tractor a ford 6700 and the owner said the ac compressor belt would keep jumping off and I am working on the ac so how can this problem be fixed I thought i heard a solution to the problem a few years back but cant remember what it was, does anybody know how to fix it? Thanks

showcrop · Sep 18, 2020

Generally speaking belts jump off when pulleys are out of line. Generally speaking pulleys get out of line due to bad bearings. Does the belt run on any idlers?

Tx Jim · Sep 19, 2020

I also own a model 6700 that is difficult to keep AC belt in place. Does your tractor AC belt have an idler pulley. I've discovered belt remains in place longer if AC compressor clutch is disengaged before stopping engine from operating. I also utilize Gates "green stripe" belt which IIRC the # is 9450 BUT I need to check # after the sun comes up. I keep a spare because as you probably realize once the AC belts jumps off it's more difficult to keep it in place.

sotxbill · Sep 19, 2020

yes,, partially due to the long run between the belts and the jerking of the compressor pistons, the off side of the belt is jumping greatly.

This is worst at 1200 rpms or so and will usually jump off when passing that rpms...

keeping belt razor tight will lessen it.

Not turning on compressor on till your at 1900 rpms and turn it off before you throttle down will lessen it.

Adding the additional idler pulley to the existing bolts on the timing cover will fix it. This idler pulley will keep it from flopping in the middle of the span between the crank and compressor. I have done this on 3 different tractors now.

Changing over to the sanden compressor will eliminate it.

sotxbill · Sep 19, 2020

forgot.. also I paint the ac belt bright red, so that i can find it in the field when it jumps off...

yes, its that bad with out the idler pulley, and sometimes with the pulley will still jump off. I still have a 7710 with that setup that does it on occasion with the pulley. Luckly the others are finally new enough to have the newer compressor and life is good.

NHbalerman · Sep 19, 2020

Thanks for the help. It does have a idler pulley but it is the v belt kind I figured that a flat kind of pulley would work better

Matt in Oz · Sep 19, 2020

Had a 7700 do the same thing, it had a techumesh? compressor from memory. Welded a plate across the outside edge of the compressor mount drilled two holes and I think used two 3/8 bots into two blind holes on the outside face of the compressor with nuts and washers to tension against the plate. Fred Wearing had this problem with a 8700 and used this system. It lets you get the pulleys and belts square and tight.

Fred Werring · Sep 20, 2020

Here's a link to what matt from oz was talking about...gives you a picture.

Still managed to throw the belt once this summer while baling...couldn't find it, had a spare in the tractor. Not gonna bale hay in a cab tractor without AC (yes, I've gotten soft).

Don't know if you've got this problem or not, but I replaced the bottom bolts on the compressor with studs. I was losing compressor oil whenever I loosened the bolts to tighten the belt. Made the studs from all-thread, nothing fancy.

Good Luck

Fred
Compressor bracket

ac compressor belt jumping off

NHbalerman

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showcrop

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Tx Jim

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sotxbill

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sotxbill

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NHbalerman

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Matt in Oz

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Fred Werring

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