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Ran D. St. Clair · 08-16-2009, 09:54 AM

Hauling AC…

So much for not being in a hurry to spend money…. I purchased my air conditioner (Coleman Polar Cub, 9200 BTU, 9A), and generator (Honda EU2000i (17A maximum, 13.3A continuous). Naturally I was eager to put them together and see what would happen. Unfortunately the RV place where I bought them was booked up on installations for almost 2 weeks, so I decided to install the AC myself. The only part I was at all concerned about was getting it up on top of the truck.

The AC unit came packaged on its own small pallet, with a cardboard box cover including reinforcing cardboard at the corners, presumably so they could be stacked. The pallet had two fairly sturdy self tapping screws installed with plastic bushings that fit into holes in the sheet metal on the bottom of the unit. They did not hold the unit down onto the pallet, but they did act to keep it from sliding around on the pallet. After removing the cardboard top, I put several loops of rope over the unit and under the pallet to make sure they would stay together. I also reinforced the front cross piece on the pallet with a few sheet rock screws. I didn’t want the staples pulling apart for what was to happen next. I then tilted the pallet and the AC unit 90 degrees nose up and shook it around a bit to make sure it was going to stay together.

A friend of mine and I set up a single ladder up against the back of the truck at a comfortable climbing angle, and also so the top of the ladder extended past the top of the truck by only a few inches. We tied a stout rope to the front cross brace on the pallet and threw the free end up on top of the truck. We set the pallet on top of the ladder, which meant it was sitting nose up about 80 degrees, roughly balanced on the back corner of the pallet. I then climbed up on top of the truck and started pulling it up with the rope. Meanwhile my buddy was pushing and guiding it up the face of the ladder from below. The unit weighs about 90 pounds, but it was easy. In less than a minute it was at the top of the ladder where we gently laid it flat on top of the roof. I might have been able to do it entirely by myself, but having two people made it much easier and safer.

Once on top of the truck it was just a matter of shifting it into place and bolting it down. Just 4 bolts between a metal bracket that mounts on the ceiling opening and the AC unit above and it was weather tight. The previous work I had done to make the 14.5” x 14.5” opening and reinforce it with 2x6 rafters worked perfectly. I won’t bore you with the rest of the installation. The instruction manual was adequate, and it was pretty simple. Some of the self tapping screws didn’t want to go into the sheet metal, but drilling the holes out a touch fixed it right up.

I bought a heavy duty extension cord, 3 wire, rated at 15A, cut off the female end, and temporarily wired it into the unit for initial testing. The generator needed oil and gas, but it took longer to read the owners manual than it did to get it running.

I don’t have my clamp on AC and DC Ammeter yet, so I don’t have hard figures but I did learn a few things. The generator seemed to handle the air conditioner just fine, at least on a cool day, which is hardly a difficult test. There was also no other load on the generator, like a battery charger, so it was far from a worst case scenario. I was able to run the generator in economy mode and it was able to handle the compressor turning on without stalling the generator. When the compressor was running in high cool mode, switching the generator from regular mode to economy mode allowed it to slow down considerably, implying that it was not working hard to keep up with the steady state requirements of the air conditioner.

I was forced to run the generator in free air on the ground next to the truck. My generator bay needs to have a hole cut in it to allow exhaust air to exit. It has plenty of holes in it now, just not in the right places. As a result the generator was breathing some of its own exhaust and probably would have overheated if given the chance.

I don’t recommend this, but I wanted to see what would happen if the air conditioner was dealing with a really hot day, so I put the vinyl cover on it. Ok, true confession, I forgot that the AC cover was already up there. In about 5 minutes the back pressure built up in the compressor and the generator started surging. Shortly thereafter the red light on the generator came on and it stopped providing power. The engine was still running, and the circuit breaker never popped, so it appears that the internal electronic circuitry cut the power to the exciter winding. No permanent damage was done (as far as I know). I reset the generator by stopping and restarting it, and of course I removed the AC cover. It may have been stupid (OK it was stupid) but I consider it a valuable learning experience. I now know what an unhappy generator sounds like, even before the red light comes on and it cuts the power.

Unfortunately it was a completely uncontrolled experiment so I don’t know if it simulated a 90 degree day or a 150 degree day. I do know, however that the generator is the weak link in the chain, and that it will protect itself if pushed too far. The manual warns, however, that I should not rely on it to protect itself in this way, as this sort of abuse will shorten its life.

To be continued...

08-16-2009, 09:54 AM	#28
Ran D. St. Clair Senior Member Join Date: Apr 2009 Posts: 212	Hauling AC… So much for not being in a hurry to spend money…. I purchased my air conditioner (Coleman Polar Cub, 9200 BTU, 9A), and generator (Honda EU2000i (17A maximum, 13.3A continuous). Naturally I was eager to put them together and see what would happen. Unfortunately the RV place where I bought them was booked up on installations for almost 2 weeks, so I decided to install the AC myself. The only part I was at all concerned about was getting it up on top of the truck. The AC unit came packaged on its own small pallet, with a cardboard box cover including reinforcing cardboard at the corners, presumably so they could be stacked. The pallet had two fairly sturdy self tapping screws installed with plastic bushings that fit into holes in the sheet metal on the bottom of the unit. They did not hold the unit down onto the pallet, but they did act to keep it from sliding around on the pallet. After removing the cardboard top, I put several loops of rope over the unit and under the pallet to make sure they would stay together. I also reinforced the front cross piece on the pallet with a few sheet rock screws. I didn’t want the staples pulling apart for what was to happen next. I then tilted the pallet and the AC unit 90 degrees nose up and shook it around a bit to make sure it was going to stay together. A friend of mine and I set up a single ladder up against the back of the truck at a comfortable climbing angle, and also so the top of the ladder extended past the top of the truck by only a few inches. We tied a stout rope to the front cross brace on the pallet and threw the free end up on top of the truck. We set the pallet on top of the ladder, which meant it was sitting nose up about 80 degrees, roughly balanced on the back corner of the pallet. I then climbed up on top of the truck and started pulling it up with the rope. Meanwhile my buddy was pushing and guiding it up the face of the ladder from below. The unit weighs about 90 pounds, but it was easy. In less than a minute it was at the top of the ladder where we gently laid it flat on top of the roof. I might have been able to do it entirely by myself, but having two people made it much easier and safer. Once on top of the truck it was just a matter of shifting it into place and bolting it down. Just 4 bolts between a metal bracket that mounts on the ceiling opening and the AC unit above and it was weather tight. The previous work I had done to make the 14.5” x 14.5” opening and reinforce it with 2x6 rafters worked perfectly. I won’t bore you with the rest of the installation. The instruction manual was adequate, and it was pretty simple. Some of the self tapping screws didn’t want to go into the sheet metal, but drilling the holes out a touch fixed it right up. I bought a heavy duty extension cord, 3 wire, rated at 15A, cut off the female end, and temporarily wired it into the unit for initial testing. The generator needed oil and gas, but it took longer to read the owners manual than it did to get it running. I don’t have my clamp on AC and DC Ammeter yet, so I don’t have hard figures but I did learn a few things. The generator seemed to handle the air conditioner just fine, at least on a cool day, which is hardly a difficult test. There was also no other load on the generator, like a battery charger, so it was far from a worst case scenario. I was able to run the generator in economy mode and it was able to handle the compressor turning on without stalling the generator. When the compressor was running in high cool mode, switching the generator from regular mode to economy mode allowed it to slow down considerably, implying that it was not working hard to keep up with the steady state requirements of the air conditioner. I was forced to run the generator in free air on the ground next to the truck. My generator bay needs to have a hole cut in it to allow exhaust air to exit. It has plenty of holes in it now, just not in the right places. As a result the generator was breathing some of its own exhaust and probably would have overheated if given the chance. I don’t recommend this, but I wanted to see what would happen if the air conditioner was dealing with a really hot day, so I put the vinyl cover on it. Ok, true confession, I forgot that the AC cover was already up there. In about 5 minutes the back pressure built up in the compressor and the generator started surging. Shortly thereafter the red light on the generator came on and it stopped providing power. The engine was still running, and the circuit breaker never popped, so it appears that the internal electronic circuitry cut the power to the exciter winding. No permanent damage was done (as far as I know). I reset the generator by stopping and restarting it, and of course I removed the AC cover. It may have been stupid (OK it was stupid) but I consider it a valuable learning experience. I now know what an unhappy generator sounds like, even before the red light comes on and it cuts the power. Unfortunately it was a completely uncontrolled experiment so I don’t know if it simulated a 90 degree day or a 150 degree day. I do know, however that the generator is the weak link in the chain, and that it will protect itself if pushed too far. The manual warns, however, that I should not rely on it to protect itself in this way, as this sort of abuse will shorten its life. To be continued...