Just when I thought I was out...they pull me back in

[working on it]

I finished my TTT on 6-16-13. So I thought. When test loading, at full (simulated) travel weight, I discovered that my calculations were way off on tongue weight. So I took measures to correct, but didn't like the junkyard look of the quick fix. Then I decided to move items around a bit, especially the 2nd water jug (moved from rear to front of cabin), and the battery (moved from rear to tongue box). Naturally, moving the battery made me have to reinforce the tongue box, and incidentally discovered a serious drain of power (battery was almost dead). After reviving the battery, running new cables front to rear, eliminating the power drain (inverter only to be hooked up when needed), and adding a master battery cutoff in the rear...I thought I was finished, for the second time. No such luck. To quote Michael Corleone in Godfather 3

Just when I thought I was out...they pull me back in

The gods of trailer building have me at it again...as I finished, I hooked up the electrical, and went into the cabin to reset the radio (unhooked for a month), and as it was 95-98 degrees in the garage, and hotter in the trailer, I turned on the A/C. % minutes later, the old problem of thermal overload started up again. The trailer would only cool to 89 degrees before the compressor shut down, and would rise to 98 degrees in the 15 minutes it took for the compressor to kick back in. I thought that I had licked that problem, and had, until summer heat made the heat transfer from the system over limits. Once again the exhaust temperature would reach 150, and the A/C would revert to fan only. So I (once again) tested the exhaust temp with opened ducting...it rose to 122 and stayed there. Tested that way, I ran it for two hours, nonstop, cooling the trailer to 65 degrees at 42% humidity (from 98 at 75%), while it was blowing 41 degree air into the cabin. Here I am again having to re-do the A/C ducting, by eliminating the internal heat-retaining rainshield inside my wall vent. If that doesn't finally do the trick, then I'll eat crow and eliminate my remote ducting, and just run the A/C venting straight back (may have to cut a hinged door in the upper left quadrant of the hatch?). Heres a link to my previous tribulations with the A/C http://www.tnttt.com/viewtopic.php?f=21&t=54945 Maybe some day, it'll be done. But I'll not say so, lest I remain jinxed.

[working on it]

UPDATE, 8-4-13 I hope this ends this problem: re-configured for the third (or is it the fourth?) time> A/C exhaust ducting and vent. As previously related, I needed to remove the vent from blocking the exhaust airflow (even though I had gutted it, the flow-thru wasn't enough); still needed it there to seal the hole, and cover the duct end, if only to match the other three vents already in place. I put in new pieces, aligned the duct as straight as possible, for a smoother airflow, and re-insulated and taped it gain. Then, the outside vent body was attached to the wall with a stainless piano hinge, and sealed with OSI Quad and rubber weatherseal pieces for rainproofing the duct when not used (ducting flows downhill to the A/C drainpan, just in case). Propped open when in use, and sealed and locked with a draw hasp when not. I added non-functional screws all around the perimeter to copy the mounting screw appearance of the other three vents. Just need to touch-up paint the OSI, and fabricate the actual screw-in vent prop.I don't even want to think about how many hours I've spent to this end...and I hope it is the end> A/C exhaust chapter closed. Pics:

[Junkboy999]

Man I hope I don’t have to go through all that when I start my build. I want my AC center mounted kinda like 2 Bits did his and the Little Swish Tear builder did theirs.

I’m wonder if you thought of this idea. I know it would be the 5 or is that the 6 make over ( ha hahah laughing with you not at you ) you would still need ducting and this would call for two removable ducts for the intake and outlet cold air. But will sure solve your heat problem.

I forgot what your inside looked like. But if you just had a slide out AC unit into the cab area it would be even simpler. Just kicking out ideas.

[Junkboy999]

Ok This might be the best option. Slide out AC this top corner . The slide out tray will include a drip pan like asianflava posted in your other thread ( linked above ). No ducting required, only need a good seal and a support outside when it is slid out. + it will free up storage space in your galley.




And one other thing. That plug configuration for the AC looks scary. Wichita had quite a few fires in the last two summer from people buy these small room Windows AC. They are safe but need there own dedicated 15 amp circuit.

[working on it]

Junkboy999-Thanks for your suggestions, but let me address why I couldn't apply either of your two solutions, one by one. In your first picture: the slide-out is in the "galley" area, so no controls are accessible by the user in the sleeping area. Also, my wife specified that she didn't want to have to move the A/C in and out anyway (I had proposed a slide-out, or a completely removeable unit, but she said that I should be able to figure a way to permanently mount one facing rearward..so "game on"). Once the decision was made for an internal "galley" location, I was determined to be able to enable it to be run with the hatch closed, for hatch item security (on park power; the rear mounted-generator makes that impossible when it must be used, but the using generator assures that one is "on guard" anyway, as it must be re-fueled periodically). That decision forced me to use ducting I had thought of using a lift up door, as shown in your drawing, but with my louvered vent housing mounted as a match to the other three functional vents on the trailer. But since I had already gutted the vent, I went ahead and made it a lift up cover (I simulated the gutted rainshield with foil tape, to make it weatherproof when not opened). And on to the second suggestion, 2nd picture : having the A/C sticking thru the sidewall of the cabin wouldn't work for me either, because there is not enough wall space for it (my wife demanded two doors, and two side windows).. And finally, the drip pan in the galley also catches any water entering the ducting, so that base is covered, and the scary wiring has had a dedicated surge strip added to control all elements>A/C, duct fan, chassis cooling fan< of the A/C system(the A/C unit has its own built-in breaker as well) . Any other 110vac circuits (all low amperage draw) run thru a separate GFCI. I've tested everything running at once, and never had a breaker trip, nor detected a warm wiring circuit. I appreciate the heads-up, though. As a summation, since I've tested the open duct (without cover), I see no reason that the vent in the lifted position would cause any recurrence of the back-pressure/heat retention problem that had plagued me before. But I have an ultimate (fifth version) in mind...a second hatch (cut in the galley hatch), that would allow the full A/C exhaust a straight path rearward, with no bends ([a.]back-pressure), metal work ([b.]heat retention), or louvered vents (more of both[a & b]) in the way. This would free up some galley space for a shelf, or cabinet, but we'll see. Perhaps on build #2 (probably a 5'x10').

[working on it]

New update, a year later (than 8-4-13): Very hot in my metal-skinned garage today, 105 degrees ambient air temperature (in full sun), perfect for a HOT test of the A/C ! I've already used it successfully on two outings, one hot and humid, the other much cooler (I only ran it for a few minutes, then decided it wasn't needed). I've also tested it many times at home, before and after wiring changes/upgrades. Today I made my sealed hatch test, under very hot conditions, to see if it would be self-regulating and self-cooling. Self-regulating: compressor cycling on-and-off to maintain comfortable conditions inside the cabin- with no further adjustments needed by occupant. Self-cooling: the A/C chassis is totally sealed from the outside; only the sidewall vent allows ambient air in, and with the 110vac case fan blowing that air into the chassis louvers to aid the A/C to cool itself, without a heat build-up inside (if too much heat builds up inside the hatch, the A/C will suffer thermal shutdown, and the stored Coleman lantern/stove/fuel cans and generator with gasoline stored inside would also become dangerously heated, too). Sealed the hatch. Started with the air temperature inside the garage at 105...cabin air 101.... A/C ran 10 minutes, and shut-down! I forgot to open the exhaust vent! Opened that, let everything sit an hour to get back to ambient, then started again. I let it run on full for thirty minutes, then entered the cabin, and turned the control back to where I had tested it before (#5 of 10). I forgot my phone, so I quickly retrieved it and took a picture of the temp/humidity. I let the A/C do it's thing for two hours (with me relaxing inside), and took another photo.

hi ambient air temp test.jpg (123.43 KiB) Viewed 1057 times

As shown in the photos, the temperature remained constant at my preferred 75 degrees, the humidity fluctuated with the compressor cycling (averaging 47%), and the outside temperature (probe located in the sealed galley...actually continued to fall). Ambient air temp in the garage itself remained between 102-106 (near the exhaust outlet). So, I guess I don't have to worry about overheating the galley, as long as the proper vents are opened, and the ducting is intact. And, once again, I checked the drip pan (which I went to great lengths to construct and install, to keep the galley dry), and found absolutely no moisture. That was why I purchased the LG 5k windowshaker, my 8k unit at home produces no excess moisture (other than what it uses for self-cooling), so no drips (runs, or errors!). And it cools as well as other brands, that drip all over the place. All in all, overcomplicated, but it works like I wanted it to.

• combustibles in galley
• exhaust vent must be opened!
• axial fan (inside ducting) a key component
• casefan aids in cooling chassis
• vent in sidewall allows airflow with hatch sealed
• drip pan for possible? drips
• sealed ducting routes exhaust outside galley