SLIDE LEAK FROM HELL

Had that same problem, Side seals looked fantastic (And in fact were)

Took a look under the slide topper.

Top seal wiper was NOT contacting roof of slide out. Water wold enter under the seal, and then run down teh sides INSIDE the slide out.

Fixed the seal (Built up the roof using foam rubber tape till contact was made in this case) has not leaked since.

Monaco had a problem for awhile where the roof/slide topper junctions would leak. Very hard to find and nail down. Look for rusty screws or rivets in the runner. Just a thought. From what I've read this seems to have been more of a problem over the driver's window and passenger door.

I suspect the water is coming down behind the sweep and flowing into the bedroom. I found water running down behind the sweep of my slideout and soaking the carpet. I sealed the topper with some water repellent spray, problem went away.

Get a dealer to perform a "pressure test" if you want to be sure where your problem is.

We patched everything on our main roof to no avail. Though we only had a small leak (at the head of the bed), we wanted it fixed. We figured it out by keeping our slide closed during a rainstorm. No leaking - it was the slide roof seams. Not much water got under the topper but all of it was ending up in our carpet.

If you can make sure the floor is dry, try closing your slide and flooding that (out)side with water. If none gets in, it is the slide. Alternatively, try flooding the main roof with water. Try particular spots if possible. If the leak returns, there is a leak on the roof. Check all your seals and seams.

Good luck. They can be annoying as hell until you figure it out.

If it has been going on for some time, there is a good possibility that some of the wood on the slide has deteriorated. It might be best to pull the slide and fix it right, including all that has rotted. You can usually look under the bottom of the slide after it is extended and see if any of the wood has gone bad.
On my Monaco the canopy over the slide forms sort of a valley where the water coming off of the roof is supposed to channel to the right or left to get off of the roof. I would guess that is where the leak is. The problem is that you may also have damage in the wall above the slide as well as in the bedroom floor and the only way to find out is to remove the slide.

On our slides (not Monaco) there are little plastic cups flush with the floor. These are at the junction of the floor and the slide opening. These are meant to catch any water rolling down the seals or sidewall of the slide. During the manufacturing the carpet had fibers that were dipping down into these bowls. During heavy rains the water would wick up the carpet fibers and spread out. It was amazing how mach water came in. The carpet would be sopping wet for about a foot away from the bowls.

To fix the problem I cut back the carpet so it no longer dipped into the bowls. This stopped the problem.

Another leak was due to old window sealant where the window met the outside wall of the RV. The sealant had a series of gaps no more than a half inch long at the top of the window. The water would follow the frame of the window down and then drip down one of the wall studs and flow out under the inside wall panel and get the carpet wet. Again the carpet would be sopping wet and extend out over a foot from the wall. This would only happen during heavy rains and with wind blowing towards the window.

It's amazing how much water seems to get in from tiny gaps.

Check the roof. Water does not necessarily flow straight down.