Odd behavior of AC condensation draining

[Belegedhel]

I have installed a brand new dometic low profile AC on my trailer and used the "factory" condensate catch and drain pan. I installed the AC during the early stages of a full monty, so I am confident that there are no kinks, or other interesting features to my drain hose. This work was done a couple of years ago.

So when I was running my AC recently, I noticed that after running for a few hours, no water was coming out of my condensate hose. If I turned the AC off, water would literaly pour out of the drain hose in a steady stream for several minutes. As an experiment, I decided to not turn off the AC and see what would eventually happen, expecting the condensate water to eventually start dripping into the interior of the trailer, but instead it started running down the outside.

It appear that there is sufficient vacuum created by the moving air to keep the condensate from flowing down the drain tube. Anyone else experienced this? Any suggestions for a cure?

thanks in advance!

[HowieE]

Air flow is most likely the problem but I doubt it is vacuum. To create a vacuum that would hold a 7 ft column of water is extreme. More likely the air flow is holding the water back from getting to the drain, a wave.

[Belegedhel]

Hmmm...You might be on to something--does sound more plausible than a vacuum. Guess I'll have to drop the ceiling unit again and try to see where air might be getting into the drain channel.

[HiHoAgRV]

I have the same issue with the same AC unit I installed on the rear of my 34'. That's been 5? years ago? The original AC on the front of the trailer never has this issue.

As soon as the AC fan shuts off It makes a huge gusher of water, most of the time the hose will drain it all but on occasion it will spill inside the trailer. The gusher isn't random, its every cycle that has run enough to pull humidity out of the air.

At the time there were a number of threads regarding the same problem on New 'Streams and if I recall, the problem went away with a small redesign of the AC unit. I'm betting that the airflow keeps an extreme amount of water hung up in the system, when the fan stops it all dumps into the catch system at once.

[Belegedhel]

I was surprised that if I left it run long enough, the water would begin running down the outside of the trailer, suggesting that it was making it into the catch pan, but that something about the airflow was keeping it from going down the drain tube. I guess I should try my experiment again and ascertain exactly where it is coming from in order to get on the roof. I was just assuming it was coming out of the weep holes in the pan, but maybe it was draining from the AC itself.

[kdickinson]

If it's not too late there is an option on several newer A/C's in which you can add an active pump. I paid the extra $100 for the pump and it actively pumps the condensate out of the holding pan at start up. On average it seems to pump ~ 2-tablespoons and up to ~ 1/4 cup of water each time the A/C starts up through the day. The original A/C we had (Armstrong) used to leak into the trailer and of course the drain tube from which it leaked was directly above the bed. When we replaced the A/C last year I felt the additional cost of the pump was justified

[B00merang]

I had this problem a year ago...except my AC would discharge a lot of water into the camper. Turns out my (FC's) tubes were clogged. Used high pressure air to blow them out. The second thing I was told by my AS dealer is to leave the fan on "Auto"...I had it set on low and the unit's plumbing would freeze up. Maybe look whether either of these two issues could apply to your situation. jon

[HowieE]

Originally Posted by B00merang

The second thing I was told by my AS dealer is to leave the fan on "Auto"...I had it set on low and the unit's plumbing would freeze up. Maybe look whether either of these two issues could apply to your situation. jon

The position of the fan switch should not effect the unit freezing. ACs freeze up because of a low charge. A unit with a low charge will allow the suction pressure to drop below the freezing point on the coil and if the load is low across the coil it will freeze. Generally a unit is charged with enough refrigerant to keep the coil temperature around 40 degrees. This temperature is enough to cause condensation and thus humidity reduction while cooling the discharge air.

[GammaDog]

I have precisely the same issue with water dripping (or streaming) into the trailer after long AC cycles in high humidity. It's always on the curb side of the AC unit. My condensate tube is not blocked because I also get drainage from the tube on the street side just in front of the front tire. I'm planning to have it looked into at my next service appointment.

[Jim & Susan]

We've had the problem of the condensation running down the side of the Airstream a couple of times while out camping. Turns out we were just a little out of level, so the pan was "crooked" or "slanted" just enough to throw everything off. The original Armstrong is still working in ours, so no new items have been added. Got a few drips out of the line under the fridge, but the majority of the water ran down the side.

Jim

[HiHoAgRV]

It's pretty common down here in the south for the units to freeze up in high humidity/low fan speed. Both of my trailers do it, my neighbors does it and a co-workers does it. High fan speed keeps the coils above freezing, low speed...well...not so much.

2 weeks back we had back to back nights of freeze up between 2 trailers, the common item was who ever cooked in the camper, had a freeze up. All it took to restore operation was flip from low-cool to hi-fan for :10.

I awoke to warm temps and a funny growling fan sound, knew instantly wuz up.

It's no fun at 2:00 am. Crawl out of bed, try to recall what knob does what, flip to high fan, wait for the fan to sound normal (air flow increases), once again try to recall what knob turns the unit back to "cool" and crawl back into bed..."Ouch"...sorry honey, didn't mean to awake you.

[Jack46]

I written about this issue before, but we experienced condensation drip into our trailer from both heat pump units in heat mode, but not cool mode. We recently had the two units serviced at the Jackson Center plant during our relocation west. Result is that now only the rear unit leaks into the trailer in heat mode, the front unit seems fine. We now have an appointment this fall for the local Denver dealer to pick up in Airstream's warranty for the work.