blowing 30 amp fuse

[Featherfolks]

Hello,
I am experiencing this problem when I connect to my Honda generator and I turn on the furnace. I tried changing the sequence, generator, main breakers and then thermostat with or without battery connected, but am getting the same result????
Suggestions are much appreciated
Steve Conway

[Cavie]

Originally Posted by Featherfolks

Hello,
I am experiencing this problem when I connect to my Honda generator and I turn on the furnace. I tried changing the sequence, generator, main breakers and then thermostat with or without battery connected, but am getting the same result????
Suggestions are much appreciated
Steve Conway

need better info. Are you tripping the 30 amp main breaker? It is not a fuse. Are you tripping the generator breaker? The furnace is 12 volts, not 120. It is on a 20 amp breaker.

[JimD]

Will then generator run the other things in your rig?

[Featherfolks]

We have the Jayco 17x hybrid. The green 30 amp blade fuse is blowing not the main breaker. Everything else is working with the generator. The Honda generator breaker does not trip. We were away in Maryland for a week and ran the furnace off and on, no problem. No changes or additions either.
Thanks

[Cavie]

Originally Posted by Featherfolks

We have the Jayco 17x hybrid. The green 30 amp blade fuse is blowing not the main breaker. Everything else is working with the generator. The Honda generator breaker does not trip. We were away in Maryland for a week and ran the furnace off and on, no problem. No changes or additions either.
Thanks

Are you talking about the 30 amp "Reverse Polarity" fuses? that would be the only FACTORY 30 amp fuse. Pictures would help. We have no way of knowing what the Green 30 amp blade fuse does.

[JimD]

Are these the facts - when the thermostat is set so the furnace should turn on, the 30 amp fuse blows? If this is the case the fuse should blow whether a generator is running or not since the furnace is a 12 volt item.

Blowing a 30 amp fuse means there is a heck of a lot of current flowing. Something appears to have a dead short. I hate using the term "short" because it is often used when it shouldn't.

If the fuse only blows when the furnace tries to turn on, best guess is that the problem is in the furnace itself. The furnace is fed a constant 12 volts and if the problem was in the power feed line to the furnace, the fuse would be blowing all the time without the furnace being activated.

When you turn the thermostat on it sends a 12 volt signal to the furnace to turn it on. When the furnace receives this turn on signal it energizes a relay that connects the 12 volt power feed to the various components inside the furnace. It appears that your fuse is blowing as soon as that relay energizes meaning something upstream from it is shorted.

I don't think the control line to the furnace from the thermostat would cause the 30 amp fuse to blow. I think the thermostat would be protected by a much smaller fuse. This could be tested by disconnecting it at the furnace and then engaging the thermostat. This test would energize the control line but prevent it from engaging the furnace relay.

Most likely this will not be an easy fix.

[Featherfolks]

It's been really cold here in NJ. My 12 V battery has discharged and I'm going to see what happens when I switch it out for another fully charged battery and replace the fuse again. I think the 30 amp fuse is one of the reverse battery protection fuses. My battery is definitely NOT connected wrong.
Thanks
Steve

[ALJO]

When you connect to the generator turn the RV main breaker off. Since you might have a dead battery and the converter is right-o-way under load condition it might trip a fuse (reverse fuse), special if their an issue with ground fault condition (corroded chassis ground). A furnace need at least half the capacity of the battery before it goes into a fault mode.

[Cavie]

Originally Posted by Featherfolks

Thanks for the indepth response. It's been cold here in NJ. My battery has discharged. I'm going to try again with a fully charged battery and another 30 amp fuse. This fuse is a reverse battery polarity protection fuse.
Regards
Steve Conway

You must find the fault. You can not just change the fuse. There are 2 reverse polarity fuses. Did you change the battery wiring lately? Wiring is the problem.

[Cavie]

Originally Posted by Featherfolks

It's been really cold here in NJ. My 12 V battery has discharged and I'm going to see what happens when I switch it out for another fully charged battery and replace the fuse again. I think the 30 amp fuse is one of the reverse battery protection fuses. My battery is definitely NOT connected wrong.
Thanks
Steve

What part of reverse polarity don't you understand???

[Featherfolks]

ALJO, Thanks for your response. I was able to get the blower motor going with heat after replacing the fuse, switching out the battery and switching to a full tank of LP and doing a few thermostat resets.

[ALJO]

When camping without shore-power (or generator) as soon the furnace gives trouble it means the battery is to far discharged. I usual start the generator at 12 volt reading.
Let us know if you have any further trouble.