AC Hacking a Figidaire 5000 BTU

[Rick G]

The reason your A/C froze up is that the that the return is too small a diameter. If you used an 8 inch duct ( a six inch might do it , but I would go with an 8 inch duct) I will not freeze up and you will not need the supplemental fan motor.

[Shadow Catcher]

Note that I described having a freezing problem, there are two likely causes for the coils to freeze up, low Freon or insufficient air flow and which I actually expected and anticipated the later.
The cure was to use the bilge blower to help air flow, easy to come by and not very expensive. It is by the way only running at about half speed using a PWM controller. One of my concerns in using the 4" hose was that I can use the same hoses and deck plates for the Eberspacher diesel heater.

[OverTheTopCargoTrailer]

a side ac unit.jpg (119.26 KiB) Viewed 8936 times

Above the window you can see the a/c is almost flush with the exterior ...
thats the way I want it , on the roof you can see the refrigerator vent - used to suck in the cooling air.



Now for my Crazy idea



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Now for the tricky part.... I want to cut a hole into the side metal upper most wall for a 12" tall x 16" wide 5,000 Btu A/C unit.....
On the exterior the A/C grill will be even with the exterior skin or stick out maybe 1/2" "Like above"
My whole set up will be 100% hidden under the solar panel " can't be seen from the exterior.
The pink is the solar panel cover "with the plastic" still in place to protect the cover.

a solar panel cover.JPG (88.44 KiB) Viewed 8936 times

On the inside the A/C will stick out into the trailer about 8-9" and will be installed inside a 24" x 30" cabinet.
Here you see the a/c inside a small cabinet - this draws air from the vent on the roof.

photo 1.PNG (91.91 KiB) Viewed 8936 times

The cooling air will be sucked in from under the trailer with a 4" hose & Bilge blower doing up to 320 CFM
while the A/C is operating the solar panel can be tilted forward - "OUTWARD" on the top 2-3" to allow hot air to escape.
The roof also has a rain gutter - so during rains no water can leak in....
the a/c condensate will run down the trailer exterior wall behind the panel.

During the winter months the a/c can be removed from the cabinet -
when in use I would just open or remove the cabinet door & have full solar a/c.....

I estimate with the supper insulation package full 3" thick R-15+ - that trailer should cool with 2,500 to 3,000 BTU estimated,
last year it worked to 95 deg with 5,000 BTU in full sun on the crappie insulation & metal ribs....OTTCT 1.0

I got this Idea from some RV websites - but they used a large 6" x 24" Refrigerator vent on the roof to supply the unit cooling air
the air was sucked in from the roof & then blown out the side wall- they did not use any blower fans.

Are you following my plan or need more pictures ?
I would like to get your ideas

I wanna keep as much hidden as possible


Thanks Jerry

[offroad]

The reason your A/C froze up is that the that the return is too small a diameter. If you used an 8 inch duct ( a six inch might do it , but I would go with an 8 inch duct) I will not freeze up and you will not need the supplemental fan motor.

so for this size of AC system we really need eight inch diameter lines to keep the unit from freezing up.

Some one could make a nice bit of extra cash, if they made a kit to do this for any owner. Hint Hint.

[Scooter6175]

why couldn't you use 2, 4inch return ducts?

[Shadow Catcher]

If you read the original I used a 4" bilge blower and it is at about half speed to assist air flow. One of the problems is the resistance of the air flowing through the duct. I used standard 4" pipe fittings and when you go up in size price goes up.

[Scooter6175]

I understand the use of the pump, I was just wondering why you couldn't add another 4 inch return line, thats all, not sure of the math but two 4 inch line would be similar in volume as one 8 inch line.

[pmowers]

I understand the use of the pump, I was just wondering why you couldn't add another 4 inch return line, thats all, not sure of the math but two 4 inch line would be similar in volume as one 8 inch line.

The cross-sectional area of a pipe is pi *radius^2. For a 4" pipe, r=2, thus the area is 4*pi or 12.5 sq. inches, and 8" pipe has a r=4, thus an 8" pipe is 16*pi (50 sq. inches) or 4 times the area. You would need 4 4-inch pipes to equal the area of the 8" pipe.
Rule of thumb for pipes (and pizza which is why I remember this ) is double the diameter, multiply area by 4.

[Shadow Catcher]

The goesinta and the goesouta gotta be the same size, it is a squirrel cage fan in the AC (on the inside).

[vanderhoof57]

Perfect idea for a big problem in tears. You could also install a recessed connector next to your hose and power connectors in order to connect to a regular a/c thermostat mounted on the inside of the trailer for better control. Just a thought!

[Shadow Catcher]

vanderhoof one of my concerns was to keep things water proof, simply, all control wires inside the intake hose. I actually did try a very expensive electronic thermostat with a remote thermocouple which would have been mounted in one of the cabinets, but I could not get it to play nicely with the AC. This set up kind of goes along with my "parts left out, stay home" philosophy.

[Sputterputz]

Does anyone see a problem plumbing this into a permanent tongue box? Vent the box to prevent overheating, but other wise the problems I foresee are noise transfer, (I can rubber mount the can to the tongue box, and could rubber mount the tongue box itself, and I would like to use a more permanent style hose, plastic or metal, between the tongue box and the trailer.. flex could be used inside the tongue box to the can connection.. I have room to make a reasonably sized tongue box 4 wide, 2' deep 2' tall.. Could allow me to have my battery and AC in there, with room for a wheel scotch or two..

sal

[rick e]

I hadn't thought of bringing the controls inside with me, have to look into that. All I need is on/off. I intend to slide out a drawer with the 5000btu on it with a duct into the cab. Return air will be outside air. I saw someone, somewhere in all the post I have read, had good luck with this setup.

[Shadow Catcher]

rick
One of the problems with not using a two duct system is that potentially you end up with wet cold air, and I have heard exactly that from those that did. CAG a couple of years ago was a 90 90 camping experience, ninety degrees, ninety percent humidity. The tear was nice and cool and, DRY!

I don't see any reason you could not do a tongue box install, but again one of the advantages is you can leave it home, and you can always park it in the tongue box.

The thermostat and on off switch are in the RadoShack project box.

[rick e]

Thanks for that. This entire thread is very good. I don't have much room up front on the tongue as that is where the battery will be. (close to the Chevy HHR battery which is in the back) I like my drawer under the galley to the side for the AC unit. If I have problems with humidity I can change the return to something like yours. Also I may spring for the remote control model.