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RV Doctor ColumnRV Doctor #322 Dear RV Doctor, I have a Dometic absorption refrigerator that works perfectly if stationary and level. For nine years it work well in motion and even then, when not perfectly level. The local RV repair shop tells me that the coolant level is low which requires a lot of money to replace the parts. They claim it cannot be recharged. The back side of the unit is reachable through an outside access vent. Any truth to this statement that it cannot be recharged? Bob James, ( Sacramento , CA )
Bob, the portion of the RV absorption refrigerator that is the usual culprit in such instances is called the cooling core or cooling unit. They can be recharged, but only with special equipment. There are only a handful of companies in the country tooled properly to do it. They cannot be recharged "in the field" by a local RV service shop. The normal practice, (for many years), at the dealer or repair center level, is to remove the faulty cooling unit and replace it with either a factory refurbished unit or an exchanged cooling unit from a supplier. In most cases, the recharged unit is just as good as new if properly charged with the correct amount of hydrogen gas, water and liquid ammonia and at the correct pressures. It is a fairly exact science. Your local dealer is most likely following what is considered to be "normal practice" concerning your faulty cooling unit. They must be exchanged so the shop can get credit when purchasing the new cooling unit. In other words, it would be cost prohibitive to buy a reconditioned cooling unit and not turn in the faulty one. Additionally, the refrigerator must be removed from its mounting location, oftentimes taken totally outside the RV, to have the cooling unit replaced. And unfortunately, it can be costly to replace the cooling unit on some refrigerators. At nine years old, you may want to consider a new refrigerator altogether. Keep in my, the cooling unit may be refurbished and charged properly, but all the other components; thermostats, burner, heating element, etc., are still nine years old. In my opinion, that's about the age when negative things begin happen with LP appliances. With a new purchase, don't forget, you'll receive a new warranty as well as all new components. But I would question the final troubleshooting deduction of that shop. If the refrigerator operates fine when level and stationary, the cooling unit is functioning properly. There may be some other factor contributing to the malfunction while traveling. This Doc would recommend a second opinion given your provided information. It may simply need a good cleaning and some tweaking of the LP pressure to promote its effectiveness over the highway. Give this one some thought before committing. (For a related question about absorption refrigeration, refer to House Calls a couple of issues ago).
Dear Gary, we have a Winnebago Adventurer. Our generator has 150 hours on it and it will only start if we manually hold the lever to keep the idle up otherwise it dies. We have changed all the filters. Any other suggestions? Thank you and we truly love hearing all the questions and your great answers; we all learn. Jan Carbone, ( Temecula , CA )
Jan, thank you for your kind words. From your description, it appears the choke, carburetor and/or the governor are out of adjustment. To be sure, the generator must be connected to a specialty device called a load bank. This tester will enable the generator to be set up properly while a varying, though measured, load is applied. Adjustments should only be made while connected to load bank. Perhaps someone tried to adjust the generator without one; this is a very common occurrence. Unfortunately, it is not possible to tune a generator engine by ear. Every mechanical adjustment will yield an electrical response that will affect the running of the generator as well as the output voltage and frequency. Some, but not all, RV service facilities are equipped with a generator load bank. It will be necessary to call around and find a shop with one in its tool crib. Many shops have a load bank but are not trained to fully appreciate its value when setting up or tuning up the RV generator. I do have a videotape which details the procedures for using a load bank on any RV generator. If your shop has an interest, have them contact me and I'd be happy to forward them the ordering information. No tweakin' without the proper tester!
Dear RV Doc, I have a year and a half old RV. I store it inside a metal building. It sat for about six months and when I went to use it the battery was dead. After pulling the caps the battery looked like it had been boiled to death from over charging. I usually leave it plugged in thinking the charger would stop charging. I have a Magnetek 7345 Converter. Did I damage the charger by leaving it plugged in all the time? Would I be better off disabling the Magnetek converter and buying an external charger designed to be plugged in all the time like the one on my boat? Should I just charge the battery a couple of days before a trip? I thought you should keep the battery charged. Is this correct on deep cycle batteries? Is there a way to check where the problem might be with the charger? All fuses that I can find are good and no breakers are flipped except the hot water heater I leave it off unless we are camping. Paul Kothe, ( Waco , TX )
Paul, there are differing views concerning leaving the RV hooked up to constant shore power, as well as a plethora of misconceptions that attempt to validate each view. It is my opinion a lot depends on the type of converter/charger that is equipped on your motorhome. For a generic, stock answer, I usually recommend not leaving the coach plugged in unless you are available to constantly check on the battery system, especially if your batteries are of the standard, wet cell lead-acid type. The typical, run-of-the-mill converter/charger has the propensity to overcharge the batteries when energized full-time. Most continue to charge well past the relative gassing voltage, thereby shortening the life of the batteries and creating a hazardous situation. Today, there are sophisticated, multi-step converter/chargers available that do allow unsupervised, continuous connection to the shore power. But older chargers simply did not have the technology available to allow multiple charging algorithms. Some had a "trickle" charging feature, but overcharging can still occur at any current rating once the battery voltage has reached 14.3 volts DC. In addition, the absorbed glass mat, (AGM) battery has increased the RVers electrical hope. Because AGM battery technology permits more positive plate material to be saturated by the absorbed mats in each cell, there is an automatic increase in the battery's capacity in virtually every area. More life cycles, reduced internal resistances, higher amp hour rating, more reserve capacity and deeper depth of discharge cycles are some of the improvements over other types of lead-acid batteries. AGM batteries are less susceptible to damage caused by overcharging, but unless your rig is equipped with one of those multi-stage, "smart charger," or unless you are readily available to check the specific gravity manually every four hours or so, I would not recommend leaving the unit plugged in all the time. A highly recommended, though somewhat costly, upgrade includes AGM batteries coupled with a multi-stage charging converter. The configuration I favor finds the existing converter left in place as the actual converter with the new multi-stage smart charger installed solely as the battery charger. Costly, but optimum.
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