View Full Version : Roof A/C dripping water inside coach

09-22-2016, 11:55 AM
Yesterday I got hit on the head by a big drop of cold water inside the Diesel Pusher. It was from the front A/C. Bummer.

It wasn't raining, but the A/C wax running, so it had to be condensed water from the evaporator coil.

Set front A/C to fan only and fired up the rear A/C. It can wait until morning.

Time to do some Internet research. Under the evaporator there is a little pan to catch condensed water. This has drain holes to drain onto the roof. All research pointed to the probability that these drain holes were clogged. Looks like the only way to get at them is from the top.

This morning at sunup I climbed atop the DP to remove the big plastic shroud from the front A/C. Screws wouldn't budge.

Can't find my#3 Phillips screwdriver bit, so off to Lowe's to get another. With the bit in a socket on a speed handle (crank-type socket handle) they came right out. Whew.

Off with the shroud, four big screws. Off with the evaporator cover, three big pieces of sheet metal, about thirty smaller screws. Thirty!

Surprise! Still can't really get at the drain holes. But with a flashlight I can see where they are. I can see them from above, so they're not clogged from above. Must be clogged from below. Scrape around under the edges of the A/C on the roof, fetching a lot of pine straw. Climb down and fire up the A/C. Climb up and mirabile dictu, water is running out on the roof, just like it's supposed to, where I scraped out the pine straw.

I needn't have taken anything apart. But as long as it was apart, I cleaned the evaporator coils with a brush even though they didn't really seem to need it.

Reinstall the sheet metal, all thirty screws (gotta lie on my side on the now-wet roof). Reinstall the plastic shroud.

Both A/C running now for about an hour, no dripping inside.

Moral: If condensed water drips from your roof A/C, before taking anything apart use a popsicle stick or a piece of small dowel or something to clean under the edges of the A/C on the roof. Had I done that first, I would have saved a lot of sweat. Learn something every day. At my age, forget it tomorrow.

09-22-2016, 06:46 PM
Glad you got it fixed, appreciate the info in case I have the same issue.

09-23-2016, 10:26 AM
In the process of replacing a Carrier Air V with a Coleman Mach 15,000 BTU if the technician ever brings it over and helps me lift it up on the roof.

The Drip pan does not have actual "Drain holes" what it has is a "Drip Lip" it is designed to hold a level of water for two reasons
1: To act as a water trap and prevent insects from entering via the drain channel
2: to aid in cooling (The drip pan runs under both the Evaporator AND the condenser coils, evaporation of water is very very efficient when it comes to cooling)

Two things I have found that cause either a light "Rain" or NIagra Falls (the latter when the fan shuts off) are

ON my Carrier's the "Drip Lip" is on the rear of the beast, past the condenser coils. if the FRONT of the RV is a bit low, the FRONT of the drip pan may be lower than the lip, and thus it drips inside (naturally) (On my Advent it's on the Driver's side by the way, Do not know where Coleman put theirs.....yet.)

IF the INTAKE filters get dirty, then the blower sucks hard enough to vacuum the water out of the tray and hold it in front of the evaporator coils. When the fan shuts off all this water it's been holding in suspension... FALLS (Niagra Falls)

Keep the filters clean, Level well. And enjoy the A/C while it lasts :)

09-23-2016, 06:27 PM
The air conditioner on my 5th wheel is mounted on a sloped roof. Debris collects in front, but is washed away from the sides in any good rainstorm.

But the pile in front can turn to compost if you don't get up there and clean that up now and then.

09-23-2016, 06:40 PM
In the process of replacing a Carrier Air V with a Coleman Mach 15,000

The Drip pan does not have actual "Drain holes" what it has is a "Drip Lip"

Your Carrier may have a drip lip, but my Colemans both have drain holes. I'll bet your new Coleman will, too -- although mine are 19 years old and the design may have changed.

09-24-2016, 11:13 AM
Will check it out if it ever gets here... And I'm getting tired of waiting for it.

09-24-2016, 11:27 AM
Will check it out if it ever gets here... And I'm getting tired of waiting for it.

I think you'll like it when it gets there, although some aspects of the design fail to excite my admiration as an engineer. For example, that sheet metal cover over the evaporator could have been designed to be secured with, say, four screws, without loss of security or rigidity. Or no screws at all, with latches instead. And having to remove four wood screws to change the ceiling air filter! Good grief.

In the main, the A/C units are actually one of the best-designed features of this motor home -- though that is faint praise. For example, I often wonder what cretin, what moron, what imbecile, what dolt at the Damon factory thought it would be a good idea to use carpet in the bathroom.