Rain leaking into trailer via AC bolt

Thanks for all the suggestions. I think I'll just tighten all the bolts down for the time being. The rubber gasket doesn't look over squashed. No point going to a lot of wok if not necessary.

I wonder if a split washer under each bolt head would help stop the unscrewing ?

Perhaps you need to change the flange gasket or whatever the gasket is called under the air conditioner. Over time the bolts or screws loosen and have to be checked, once in a while.
The gasket shrinks.
Three years ago we got caught in a driving rain and water came in the front air conditioner. It wouldn't come in sitting still.
The gasket was shrunken or over compressed.
We don't have bolts down through the roof. They are just screws, through the roof, from inside, into the air conditioner. I haven't looked at it but this is what I've been told where they fixed it, best I remember. They take very good car, of the unit.

Those 4 hold down bolts should be 'snug'

torque wise.......about 40 INCH pounds.

Most folks don't have an INCH Pound torque wrench.....most have FOOT Pound torque wrenches

That's why 'SNUG'

Over-tightening the hold down bolts will distort roof gasket.
A new gasket is 1" thick and when installed should be compressed by half (1/2")

Over-tightening can also cause the drip pan drain holes to be blocked by making contact with roof.

5 yrs. old shouldn't need replaced.
It leaked due to loose bolts.
Loosen them then tighten just 'snug'

To replace gasket you have to pull the A/C unit up/out of roof opening.
That means disconnect electrical connections
Lift it up/out
Remove old gasket
Clean up bottom of pan and roof if needed
Install new gasket and reinstall A/C unit without getting gasket out of position/twisted.

X2 on above post and...if you have to replace the gasket some come with 4 plastic tabs now. If you get one with plastic tab. Tight is when you see tab start to visibly compress. Without tab I always went with what felt good and then see if it was good. No particular torque other than "snug" best I could find out. But once a year, give bolts a 1/8 turn tighten. Then once gasket is down to nothing then replace with new gasket. I gave over $30.00 for mine. Much cheaper on-line if you can wait and if condensation pan is not problem. If you take A/C out to put in new gasket and break any of those plastic air diverters on front and rear of inside a/c there real name is called (in case you have to order)is called "Louvers" and are about $16.00 each for each end. Mine was Coleman Mack. A/C out and back in was about 1 1/2 hours.

Good Luck

I've read a suggestion to tighten them every couple of years, if you see that you can, because the vibration and natural changes occurring in wood result in loosening. When it leaks and you can't tighten/compress the rubber any more, then it's time to replace the gasket.

How difficult? Don't know, but I "think" that you should be able to pull the old gasket from under the unit, and put a new one on in the same way. You may have to wedge something on one side, do this side first, then other sides. The unit is sitting in the metal tray, and the gasket is under the tray. There are no pipes or hoses to get in the way, only 120V wires.

Q4: Make sure the weep holes in the condensate pan are clear.

If they are clogged, clean them with a pipe cleaner.

Yup, you have to get up on the roof and remove the cover.