What I learned from an RV Air Conditioning Service call.

Over 100 degrees already in Austin Texas (May 2011). Even too early for most Texans.

First time we used the RV air conditioner and cared. We purchased the unit in the fall of 2010 so no real need to use the air conditioner, and not enough hot weather when we did "test" it to actually notice. [ Amazon link is a representative RV air conditioner ]

Our RV is a 2010 Open Range 399BHS. We love the RV and its been a great RV so far.

But when we turned on the main air conditioner (we have one in the front bedroom, and one in the living area which we would consider the "main" air conditioner) we found that PRACTICALLY speaking, the main air conditioner, while it does put out cold air, could not cool the RV down at any temperature. In other words, if you set the thermostat for 70 degrees, unless the outside air was darned close to 70, it was going to never shut off the main unit.

I called the local Austin RV repair person that we normally used and had him check it out. The main reason for this is that I have no capability to assess what is abnormal versus normal.

Here is what I learned.

* In the Open Range 399BHS, there seem to be two ducts that run lengthwise from the front of the unit to the back of the unit. There are several vents all along the camper.
* The "cutouts" (see the pictures below) which allow the air conditioning unit to pump air into the ducts are VERY VERY small. Rick our repair person, did use some duct tape to try to open the cutout bigger, but was limited by the Open Range design.
* The ducts in the BACK of the unit put out more air than the ones closest to the unit. I thought this odd, but Rick said that the air flow will often go directly over the vents and won't put out air until a little pressure builds up.
* The way that many of these air conditioner guys measure if the units are functionally working properly is to measure the temperature at the vents. They did so on mine and said the temperature was 20 degrees below the room temperature which is considered to be normal/proper operation.
* By turning ON the front air conditioner in "fan only" we could build up enough pressure in the overall ductwork to push the cold air out of the bedroom into the rest of the unit.
* Rick said that with our current Open Range, there was little that could be done as it looked to him as if the design was the primary limitation.

It was very good to know that the systems were functioning properly and we'll learn much more about what some of these things mean on our energy bill this summer.