There should be a fuse on the power converter board for each of the appliances. First step, due to your description above would be to locate the fuse on the board for the heater and replace it. Let us know the result.
After checking the fuses (check all of the fuses), Check your Battery voltage with and without the 120 volts plugged in, if the voltage drops there is a problem with the converter.
Next, try running the furnace on just the 120 volt system by disconnecting the battery.
Also, check your voltages at the fan using battery only, battery with 120 volt, and 120 volt only (pay special attention to polarity, if polarity reverses during one of the tests, that is your problem).
My guess is that your Converter is somehow reducing your voltage below what is needed to run the heater, perhaps through reversed/crossed wiring. Another possibility is that there is an internal short in your Converter and it is creating an open circuit or has an internal short which is lowering the voltage when plugged into shore power.
Also, check your grounding, make certain all your grounds are well connected and not corroded.
Good Luck !!!
And...
Happy Scamping !!!
PS: I am about to embark on a similar electrical mystery tour with my own trailer.
Figure out which fuse is for the heater (It's number 8 on a Casita..... pink wire).... You have a hot side and a dead side at the fuse block without the fuse in place. Take a voltmeter and check the voltage at both sides with the fuse in and see if there are any inconsistencies
There should be a fuse on the power converter board for each of the appliances. First step, due to your description above would be to locate the fuse on the board for the heater and replace it. Let us know the result.
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After checking the fuses (check all of the fuses), Check your Battery voltage with and without the 120 volts plugged in, if the voltage drops there is a problem with the converter.
Next, try running the furnace on just the 120 volt system by disconnecting the battery.
Also, check your voltages at the fan using battery only, battery with 120 volt, and 120 volt only (pay special attention to polarity, if polarity reverses during one of the tests, that is your problem).
My guess is that your Converter is somehow reducing your voltage below what is needed to run the heater, perhaps through reversed/crossed wiring. Another possibility is that there is an internal short in your Converter and it is creating an open circuit or has an internal short which is lowering the voltage when plugged into shore power.
Also, check your grounding, make certain all your grounds are well connected and not corroded.
Good Luck !!!
And...
Happy Scamping !!!
PS: I am about to embark on a similar electrical mystery tour with my own trailer.
As Always,
Happy Scamping !!!
Figure out which fuse is for the heater (It's number 8 on a Casita..... pink wire).... You have a hot side and a dead side at the fuse block without the fuse in place. Take a voltmeter and check the voltage at both sides with the fuse in and see if there are any inconsistencies
Joe & Linda
New River, Arizona
2013 Casita SD 17'