Installing a/c: ventilation to keep the a/c unit from over heating

(Sorry this picture is supposed to be after the intro but I can't get it to stay  there) This is the fan I installed directly behind the a/c unit to pull the hot air out.

After installing the a/c unit and drain pan, I began addressing how to vent the area the a/c unit is enclosed in. I knew I needed to prevent the unit from over heating. When you're looking at upper 90's, 100% humidity, and heat indexes well over a 100 degrees, your a/c better work. It gets HOT in Alabama! It took me a couple of times to get it right. First, I just stuck a fan behind the unit to pull the hot air out the access door. This worked okay, but the wood paneling became hot to the touch and it didn't cool well. Then I tried turning the fan around (to pull fresh air in) and put fans in a vent located directly above the access door (to pull hot air out). This didn't work at all. The compressor would kick off in about 15 minutes. Next, I set it up as described in this post. It works great! The wood panelling right next to the unit doesn't even get warm. And, it keeps the trailer  cool even in the upper 90's. 

Next, I drilled holes in the shelf the fridge will sit on. This is to draw fresh air in through the top vent (the vent above the access door). 

I installed two small fans in the holes. The fans air flow blows  down into the compartment where the a/c unit is located. I used fans designed to use in computers. Where I originally had them installed, I needed very small fans which would pull a lot of air. With the fans installed in this location, I probably could have used something different. I bought these at Radio Shack and they were expensive. 

This is the compartment where the a/c unit sits. You can see the fans at the top of the picture. When I had to redo the ventilation, I had to take the a/c unit back out.

This is the view of the fans from above. The fridge will sit here.

I moved back a little for a better view. The fridge will sit on the top shelf and the a/c unit sits on the bottom.

I had to add a piece of paneling to separate the fridge area from where we hang our clothes in the closet. I installed some wood strips in the closet to attach the panel to. This is the bottom piece.

If you don't have a right angle drill, buy one. I used mine more than my standard drill. I like the rigid brand because you can register your tools and get a life time warranty. The warranty covers the tool and the battery. The battery warranty is what makes the deal. 

This is a test fit of the panel. This is the inside of the closet. You can barely see the clothes bar at the top of the picture.

This is a picture of the same panel but from the other side. This outlet is for powering my fridge and the two small ventilation fans installed under the fridge shelf. In an earlier post (Adding a/c: running the power), I mention a yellow cable running to the top of the closet for the fridge. This is where it ends up.

I wanted to be able to turn the two vent fans under the fridge shelf on and off. In the winter it would cause cold drafts. This is a picture of a small outlet box I installed in the back of the closet for an on / off switch.

This is a picture from the other side.

I ran some lamp wiring (with a plug already attached) through the box.

This is the cover plate and switch I plan to use.

I wired the switch to the fans. You can also see where the fridge will be installed 

This is the installed switch in the back of the closet.

This is an exterior view of the vent located directly above the assess door to the a/c unit. I don't know what it was originally intended for. Mine was sealed off with a piece of plywood. You can see the wasp nests. This is wear the fresh air enters behind the fridge. I removed the plywood (and the wasp nests).

This an interior view of the above vent. I had a screen made and installed it to keep the bugs out.

Finished up wiring the two vent fans and the switch. I just followed the directions that came with the fans.

Here's bigger view. Please note: the fans are pictured in their original location.  There's a picture earlier in this post showing the correct location. The next couple of posts will address permanently installing the fridge and a/c unit.

Installing a/c: installing the drain pan and completing the framing

When I test fitted the a/c unit, I noticed the front panel tilted funny. It looked like the unit was not level front to back.   That's when I realized that a/c units tilt down when installed in windows and the front panels are angled accordingly. I cut a strip of wood to fit on top of the the front brace for the a/c unit to sit on. This also allows the water which collects in the bottom of the a/c unit to drain correctly.

I drilled some pilot holes to prevent the strip of wood from splitting and installed with screws.

Here's a closer look.

I didn't want the unit to slide around while I drove down the road, so I tacked down some nonskid material. 

Here's a closer look.

I needed to keep the unit centered (left side to right side) in the cabinet, but I also wanted to be able to take the unit out if I needed to. It was a good thing I planned for this because I had to take the unit in and out a couple of times to correct ventilation issues. I bought some threaded furniture glides and rubber end caps (for chair legs). I trimmed the rubber caps    to about half they're length and inserted the metal glides into the caps.

I bought the correct sized tee nuts for the threaded glides.

Drilled a hole for the tee nut to fit into the side framing. The tape on the drill bit lets me drill to the correct depth. I didn't want to drill through the side panel.

I hammered the tee nuts into the side framing and screwed the glides into the nuts.

Here's a closer look. This is to tighten against the sides of the a/c unit to keep it from moving left and right while I'm driving down the road. I can also adjust the placement of the a/c unit from left to right by screwing this in and out. I placed these in the framing on both sides of the a/c unit.

I used a hole saw bit to drill the hole for my drain. The size of the bit is determined by the diameter of the drain pipe shown a couple of picture down. 

Drilled the hole. 

A closer look.

I put plumbers putty on the drain assembly I bought. I found the drain assembly at Lowes in the RV plumbing section. It can't be the kind that goes under the sink in your house. Those have a hole for the lever to raise and lower the drain plug.

Here I've placed the drain assembly in the hole I cut in the jelly roll pan.

Then I tightened the nut down onto the rubber washer and the plumbers putty.

Here's the view from the top.

Here's the view from the bottom.

I placed the drain pan where its going to go and shined a light down the drain.

This showed me where I need to drill the hole in the floor for the drain line to exit.

I drilled the correct sized hole through the floor of the trailer for the drain.

Before I permanently installed the pan, I placed a wood shim under the pan's lip to angle the pan toward the drain hole. This  lets the water run to the drain instead of sitting in the low end of the pan. The pan is a little flexible so this worked great. This is a picture of the shim I used not where it is installed. The shim is installed on the wood ledge just to the right of the pan's lip in the picture above.

This is a picture of the installed drain pan looking from the outside of the trailer. You can see how it's angled to drain toward the drain. You can also see the metal corner brackets I used to install the support framing the a/c unit sits on.

This is a view from the inside of the trailer. You can see the wood shim  mention a couple of picture ago installed just to the right of the pan. I used cable clips to hold the pan in place (pictured on the right side of the pan). 

Here's a close up of the wood shim and the cable clips.

I ran a garden hose through the hole I drilled in the floor of the trailer. The reason I used a garden hose is its flexible and I had it laying around. A guy at the local hardware store showed me the fittings I needed to attach the hose to the drain.

I installed the a/c unit. After I centered the unit, I tightened the threaded casters I'd installed earlier.  You can see them  pictured here tightened against the side of the unit. Notice the units power cord on the bottom left corner. I had to run the a/c unit's electrical plug through this gap before I installed the piece of wood the unit sits on. 

Another picture. You can see the drain on the right side going out the floor.

This a picture of the hose running under the trailer. I didn't want water dripping on the door side of the trailer, so I ran it to the other side of the trailer.

The end of the hose.

I drilled the center out of a brass end cap and got a filter to screw into the end of the hose to keep bugs from building nests in it and blocking it up. 

Here you can see the screen in the end cap.

Installed and draining.