by Jack Bradshaw – Foretravel
One of the most important things needed in your coach and often taken for granted is your roof air conditioner. I know some of you are slowing down for the winter or in a place where your roof air is not needed, but it won’t be long before it will be needed again. So I thought I would give you a little info on how it works and some maintenance tips to keep it in top working order.
There are only a few things that should be done to maintain the efficiency of today’s RV air conditioner, but those few things are very important. I thought it might help to understand the mechanics of the air conditioners’ operation. In order to produce a dramatic temperature change, the air conditioner takes advantage of a principle of physics: when a liquid evaporates, a significant temperature drop occurs. The air conditioner compresses the refrigerant; the refrigerant becomes hot and is then circulated through a high-pressure condenser coil. A fan blows away the heat, and the now-liquid refrigerant is circulated through a restrictor to the evaporator coil. When the liquid refrigerant passes through the restrictor (either as expansion valve or capillary tubes), it is allowed to evaporate into the larger chamber of the evaporator, which lowers its pressure and gives a drop in temperature. Simple, right?
To better understand refrigeration and air-conditioning systems, we must recognize that there is no such thing as “cold”. Cold is an adjective describing a noun -a cold drink, a cold breeze, etc. Heat is a noun, and it is heat that must be dealt with by absorbing it into a medium and moving it to another location. Heat is absorbed from the air by the evaporator, moved to the condenser via the refrigerant, and then discharged by exchange into the outside air.
Now that we know the basics of operation, let’s get to some maintenance tips. I was taught many years ago that there are three important points to remember about air conditioners: airflow, airflow, airflow. You get the idea! The blowers, the coils, and the air ducts are all designed for a specific amount of air volume. When restrictions are present, dramatic changes in efficiency occurs. First and foremost, the filter in the return air register should be clean. There is a very simple way to determine when the filter needs cleaning if it is dirty it needs cleaning. This may seem simple but it is important to keep a clean filter. Frost and ice forming on the evaporator often are caused by a combination of recirculation, low fan speed, a dirty filter, high humidity, and an unrealistically low thermostat setting.
Every year or two, the condenser should be inspected. If airborne particles such as pollen or cottonwood seeds accumulate on the condenser, it won’t be able to discharge the appropriate amount of heat due to the reduced airflow. If the condenser can’t get rid of the heat, it will affect the amount of cooling available. Remove the cover and make a visual inspection. Any debris can be removed with a soft brush or blown away with low-pressure compressed air. While the cover is off, get rid of any little critters nest. Also, inspect the condenser fins for damage. Fins crushed by a tree limb or by hail can be straightened with a fin comb.
Well, as you can see, some simple preventive maintenance can keep you cool for many days while traveling around.