Weird Electrical Issue

[onebud1]

I have a 31' 1999 Class C Designer. The last couple of times out, I have had this problem. While plugged into 30 amp shore power, when I turn on the electric water heater switch, the frig switches from AC to propane, and gives me the message LO AC. When the water heats up and the heater turns off, the frig goes back to AC. Running lights, TV, etc do not induce the same problem. Any ideas?

[Doug]

Thinking out loud

Maybe your heating element is on its way out and the resistance has increased to draw more than its share of power.
Seeing the 30 amp source drop to a certain level due to this increased draw by the electric element is causing computer to switch frig from ac to propane?

Just a thought.

Best regards,
Doug

[LkptRvPilot]

Yeah, I think I'm on the same page as Doug (except resistance would decrease for higher current draw). You can measure the AC voltage either at the fridge or water heater before and after the water heater kicks on. There should be a few volt drop when the water heater is ON, but not a large drop.

Also, off the top of my head, due to the age of your vehicle, corrosion on the wires at the connection points (check main plug blades for discoloration) or perhaps the resistors/caps on the fridge detect circuit are drying out and causing erroneous voltage readings. Just WAGs at this point until we get some voltage readings.

Does this occur when other large loads are applied (AC or microwave)?

Kris

[tnchuck100]

A water heater heating element will not increase resistance and draw more power. It does not act like a motor.

Your most likely cause is going to be a poor connection at the service pedestal or when the wires connect at the converter. Feel the plug at the pedestal. Is it warm or hot? Do the blades on the plug appear to have been overheated? At the converter are the wires from the power cord scorched or showing signs of overheating? If you find this to be the case you will need to remove the connections and cut of the bad wire ends to get clean copper. You may have to use a wire brush and sand paper on the terminals to clean those up.

Something is causing a drop in voltage. The water heater is about a 1500 watt load. But it, itself, is not causing the problem. It is merely the item that causes the real problem to become apparent.

[onebud1]

Looks like we are going to replace the power cable. Will let you know how that goes. Thanks for all the suggestions...

[skymutt]

In the for what it's worth category....I agree with TNChuck. You don't need to replace the cable. Just check the ends and replace whatever is corroded or shows signs of heat.

[onebud1]

Just wanted to say thanks for the suggestions and post an update. Replaced the Power Cable and Transfer switch (arcing inside switch...thank goodness it didn't catch fire). All is well now.