Discolored Extension Cord Plug
Dear RV Doctor:
In the June 2015 “House Calls” column (page 20), a reader queried about discolored cord contacts. I have a similar issue where the female receptacle on a 15-foot, 50-amp extension cord has turned brown, presumably due to heat or spark gapping. There is no sign of damage on the male plug for the coach main power cord, but at times the connection between the two has been overly hot. Do you think the discoloration signals it’s best to replace the extension cord?
Bertram Pryor, F422173
Norman, Oklahoma
Judging from the photo you supplied, it appears that your extension cord has sustained some damage. High amperage draw; dirty, worn, or loose contacts; high heat; and low incoming voltage all can lead to the problem you’ve noticed. Water instrusion at the plug cap (moisture seeping into the contact points) also can hamper the proper transfer of electrical energy.
You’ll notice the 50-amp plug cap on the end of the shore power cord is molded to the cable. This is a National Electrical Code (NEC) requirement placed on the coach manufacturer. However, from your photo, the extension cord does not appear to have a molded plug on the receptacle end (and likely not on the male end). Since that extension cord reveals that the contacts have become fatigued and possibly corroded because of exposure to high temperature, I recommend a new extension cord that is RV-approved and equipped with molded plug caps at each end. It is probably a bit more expensive, but scrimping on safety-related items is not recommended. Always obtain the best you can find.
The male end of your shore cord looks somewhat corroded. I also recommend cleaning and treating all male and female electrical contacts and connections with DeoxIT at least once per camping season. You can read what I have to say about DeoxIT at http://goo.gl/KIkPy.
Incorrect Refrigerator Heating Element
Dear RV Doctor:
The AC heater went bad on my RV refrigerator, so in its place I hooked up a defrost heater from a household refrigerator. It started cooling, but then I heard the liquid boiling, so I unplugged it. What would happen if I plugged it back in and left it plugged in?
Don McKown
Via Email
Do not plug it back in without an approved, properly sized heating element in place. The wattage rating of a heating element is based on the size of the refrigerator cooling core. The defrost heater from a residential refrigerator probably is way too hot for the boiler section of an absorption refrigerator. Allowing a nonauthorized element to continue to heat the boiler could cause the siphon pump in the boiler section to overheat and become blocked.
Overheating that section of the cooling unit can cause a litany of other problems as well. It will be necessary to replace the heating element with the correct part number based on the make and model of that refrigerator. All heating elements are not created equal.
Delamination Concern
Dear RV Doctor:
We returned to the RV scene after about 15 years and bought a Thor Motor Coach Hurricane with the Triton V-10 engine. We had the rig checked by a friend who has been in the RV repair business for more than 20 years. He assured me it was good, especially since it had only 29,000 miles. However, there are some very small areas showing what I call “microdelamination.” I work in Colorado and live in Arizona, so the rig has been in the heat for its entire life. I called Thor customer service; the technician said that all is well and there are no structural issues, only cosmetic. What is your opinion?
Brent Garrison
Colorado Springs, Colorado
Without actually laying eyes on the type of delamination you’ve described, it’s hard to form an opinion, unfortunately. I’d likely trust Thor and a 20-year veteran RV technician, especially if he’s a friend. But do keep an eye on it for further acceleration. It’s possible there’s nothing to worry about, yet you’d want advance knowledge if it shows a tendency to worsen over time. See whether those small areas actually grow over the coming season. Perhaps take a well-lit, high-resolution photo or two and send them to me. I’ll see whether I can discern anything negative as it stands now.
Chassis Battery Power Dilemma
Dear RV Doctor:
We have a 2008 Dynamax on a 2007 Freightliner chassis. Without shore power, we have no chassis battery power. All the batteries measure around 12.6 volts. And all batteries in the coach and chassis are new. Do you have any suggestions?
Harry Zakorchevnoy, F417406
Forestport, New York
Is it possible there is a battery disconnect switch for that low-voltage chassis system? Some applications include two disconnect switches that operate independently. In other words, one system can be activated while the other battery bank remains disconnected. Shore power battery charging could override both. Check to see whether the chassis battery bank voltage is indeed still measureable beyond the disconnect switch.
If the voltage does pass through, next I would consider a master fuse or circuit breaker somewhere that protects the entire system. If the master fuse or breaker is blown or tripped, shore power will work, but battery power will not. And though I’ve not studied a Dynamax wiring schematic, it’s possible the ignition key has to be activated in order to power the chassis components. Unfortunately, this is the best I can offer without taking some measurements and inspecting the systems. Perhaps another Dynamax owner will offer another remedy.