The Danby Air Conditioner in a Tab320s

grassgd

I use the AC in my trailer quite a bit and really didn’t have a problem other than a crack in the plastic drip pan until I improved the venting on the unit to ensure it will perform the best it can in very hot weather. 

The modification was very successful and the unit performs very good in 100 plus temps and direct sun. The problem that I see now is the humidity becomes excessive when the temps are moderate outside and the compressor only runs a short time before cycling off.  Once this happens the humidity climbs as the water remaining on the condenser is put back into the trailer since the fan runs continuously on the Danby AC along with the water vapor from us inside the trailer.

 

This is the classic example of an air conditioner which is over capacity, which the Danby is when outside temps are only moderate.  My modification to improve the cooling air circulation on the Danby condenser has actually made this problem show up more than ever.

Since the Danby AC only runs with the fan on all the time, I plan to modify the AC to only turn the fan on when the compressor is running.  I pull the AC out to determine how to accomplish the wiring change and determined a DPDT relay can be installed and controlled by the compressor to turn the fan on.  If I was replacing the AC, I would make sure the new unit could run with the fan in auto to cycle it on and off with the compressor.

While I had the unit out I began looking at the auxiliary fan NuCamp installed in the trailer to aid in the AC air flow.  To my surprise I found the fan as installed by the factory is pulling air out of the AC compartment and not into the AC compartment which is on the cool side of the condenser.  I don’t know if mine was just installed backwards or that’s how they intended it to be.

 I removed the auxiliary fan to reverse it and found the roof top vent was installed by cutting through one of the roof aluminum structural members.

 

 Also I noticed the roof top vent is essentially about an inch and a half diameter with a bug screen which was about 40% plugged. 

 

The vent is way too small for the size of fan used.  I judged the amount of air the fan blows with the roof vent restriction is likely cut in half after cleaning the bug screen compared to the fan with no inlet restriction.

It may be a couple weeks before I get the relay, complete the modification and test to confirm if this helps as much as I hope it does.  In the meantime, I hope this sheds some light for others experiencing high humidity in their trailers.  You have to understand basic AC issues which I’m learning the hard way.

Tabaz

Thank you for this post.  Very interesting information.  My Aux fan draws air from the ceiling vent into the A/C cabinet.  Also, the last time I looked into the vent opening, I didn't notice any aluminum bracing.  This would have really concerned me.  I'll definitely be checking that screen for obstructions.

Mickerly

We tested the Danby output temperature with the AC fan on and OFF. there was no difference, just more noise.. Didn't think about checking the screens for bugs. 

MuttonChops

A]   My fan was installed to pull air in (correct direction).

B]    My 1.5 inch Vent tube/cab also was placed to Cut the Roof Framing.

C]    I replaced the 1.5 inch vent pipe { 1.77 sq inch max air flow without bug screens } with a

       4 inch pipe and Radon Hood/Cap should provides  14 sq inch max air flow.

grassgd

Installed a relay to modify the wiring on Danby AC so the fan cycles on and off with the compressor.  Tested it out in my driveway and found it works extremely well at controlling the humidity.  Outside temps were not very high so the load on the AC was not high which is when the humidity problem is the worst.

The fan will not run fan only is selected by I never ran the fan only before anyway.

The relay coil is energized with the power from the thermostat that controls the compressor.  The fan high and low wires are run to the normally open contacts of the relay contacts so when the compressor is not running the fan is off.