By Greg Gerber
RV Daily Report
SUN CITY, Ariz. — An RV technician trying to diagnose a problem with an older model RV watched as the unit’s Dometic refrigerator caught fire. His subsequent investigation traced the source to an electrical problem not related to the gas leak commonly cited as the source of refrigerator fires.
The flaw impacts RVs built in the mid-1980s to present with installed Dometic LP gas refrigerators, he told RV Daily Report. It is caused when RV owners attempt to use an adapter to connect a 30-amp, 110-volt RV to a 15-amp, 110-volt power source, whether in a campground or at home.
Adapter plug to allow a 30-amp cord to be used on a 15- or 20-amp power source.
Once this happens, the Dometic refrigerator control boards will melt down as the current seeks a new neutral connection, the technician explained. That causes the electricity to jump to the earth ground connected to the chassis via the incoming shore earth ground.
“Surprisingly, no fuses of any type blow and the Dometic control boards will catch fire,” he said. “Since they are made of plastic cases, they burn fast and quickly.”
“Many times we have seen the RV’s male plug’s 30-amp neutral side burned from bad connections caused by the RV not being bonded at the 110-volt box,” he explained. “This recipe for disaster is possible for any RV using the Dometic refrigerator prior to 2000, and possibly beyond.
“However, Dometic did replace the non-warranty board, heating elements and thermistor at my request for the customer,” he explained.
RV Daily Report consulted with two other experienced technicians, who both said it appears the scenario described above is plausible.
One of the technicians, Gary Motley, with Motley RV Repair in Oklahoma City, said he and one of his technicians analyzed the problem in conjunction with a review of Dometic’s home study course.
“Proper voltage and polarity are very important. This refers to 12-volt DC power as well as 115-volt AC power,” said Motley. “The use of a 30-to-15-amp adapter is not good when running an air conditioner.
“Over time, this can cause the connections to overheat and become corroded,” he explained. “When this happens, voltage can be lost over these connections. I have measured this while ‘playing’ in the shop and detected as much as a 9-volt drop.”
The Dometic home study course book specifically points the importance of a good neutral connection and not grounding it through the chassis, Motley noted. The manual also states all connections must be clean and tight.
“This is very important because a loose connection can produce too much heat which can create a fire,” he said.
Technicians looking into situations like this should investigate whether the refrigerator’s heating element was the correct size for that specific model and ensure that the output on the RV’s converter is showing the proper levels, Motley said.
“There are many variables that could cause the problem in this situation that are outside of the control of Dometic,” he explained. “I have never heard of this happening before.”
UPDATE: READ DOMETIC’S RESPONSE.
Article courtesy of RV Daily Report, the most comprehensive online RV industry news source.