Camper Air Conditioner Repair
RV Air Conditioners Made Simple
Master Certified RV Technician
Air conditioner problems and questions are very common to most RVers. At our shop we are often asked to repair an air conditioner unit (referred to as unit(s) for simplicity) that an RVer feels is not working properly. Most often with a little work these supposed defective units can be made to work much more efficiently. This article is intended to inform the average RVer of some cautionary maintenance steps and to answer some common questions.
Because there are different installations and models of units I intend for this first section to be generic to any unit(s) and then I will go into the individual types.
A dirty filter caused this evaporator (cold exchanger) to gum up. A dirty filter will greatly reduce efficiency.
1. The most prevalent problem with RV units is the filters not being cleaned. It is imperative that filters are clean. Unclean filters reduce air flow which can create freeze up problems, electrical problems, and efficiency problems to name a few. One of the major undesirable results of a dirty filter will be a dirty evaporator. An over simplified definition of the evaporator is the set of fins the air moves over to change air from hot to cold. With a roof mount unit you will normally only see the evaporator from inside the coach looking up into the unit when the inside ceiling assembly and /or filters are removed. When the filters become excessively dirty the excessive contaminants are pulled through the filters and will begin building up on the evaporator fins. This build up begins acting as insulation which reduces the efficiency of the evaporator. This can also create situations where the compressor can become overheated due to the use of more electrical power than normal.
2. Unlike home split system air conditioners, RV units are not designed from the factory to be recharged. As a result you cannot check an RV unit using pressure gauges without installing valves. I am often asked by RVers to check the Freon® in their unit. My answer to this request is, “When is the last time you called a refrigerator serviceman to check the charge in your home refrigerator?”. Just like your home refrigerator a RV unit is hermetically sealed (not like Johnny Carson’s The Great Swami’s envelopes in the mason jar). Hermetically sealed is an accurate technical term. If you ever take your RV unit to have it serviced ask a lot of questions and have faith in your technician before you allow them to break into the sealed system on your RV unit. In very rare instances some high end RV’s do have a split system.
3. To check out a RV unit there are two major and simple checks that should be performed.
A. Temperature change.
In other words what the difference is between the temperature of the air going into the filter and the air coming out the discharge. The technical books say this difference should be a nominal 20° with the compressor running. I have seen it as high as 32° and as low as 16°. Some considerations for this temperature difference are:
• The two thermometers used to determine the temperature difference must be calibrated to each other.
• The books say the compressor should run for 30 minutes before the temperatures are taken.
• The temperature differential will be inversely proportional to the relative humidity. The condensation out of very humid air will build up on the evaporator just as the air filter contaminants mentioned earlier and act as an insulator.
B. Amperage check.
This check should be performed by a qualified technician using the correct meters and technical information that is pertinent to the unit being checked. If the amperage readings are out of specs you may be able to improve them with a fairly extensive maintenance. However the damage may be irreversible and the components of your unit will continue to deteriorate.