Crappyjacks

I would suspect a bent jack, possible a dent or crease in the housing that is causing extra friction. Or, it could be a lack of lubrication. Does that jack run slower than the others? Is it making any sort of noise?

Evening k Mac

I would put that Jack on another corner and see what happens.
If you still blow the fuse that associated that Jack, then I would go with KD suggestion

Mike T

I agree with Mike.

Also - double check all electrical connections - make sure the screws are tight on the wires. If any wire nuts are used, take the nuts off and examine the wire ends for corrosion. Inspect the plug that makes the connection from the Jack to the body of the camper. I had one of mine fail as water got into it and corroded the connection.

I have had the same thing happen several times. In each case it was not long before the motor failed. When I pulled the motors off, they had water inside of them. The seals on the older Happijak motors can easily leak. In addition I had one jack fail due to corrosion. I tried sealing the motors and jacks with plastic bags taped on top. That looked really poor and due to the design I could not fit them well and still got water underneath. I also tried a thin bead of caulk and later added Gorilla brand duct tape. I think the tape is working. It has been 2 years since the last failure.

The issue now seems to be at least partially resolved. The new motors are placed above the jacks so at least the motor cannot directly accumulate water.

Thanks for the help guys, I was out doing my other fav. leaf peeping on the mtcy. this wknd. will try these suggestions. K mac

I have some 2005 model 4500s that have 30 Amp fuses, one for the left side and one for the right side. Mine were blowing right side fuse because I had two bent jacks. One had a 5/16 inch bow. Straightened them and no longer have a fuse issue.

Check your users manual, as 20 Amp fuses might be a bit small.