Inverter problems

[Roammer]

We have a 2019 3721RL that has burnt out 4 inverters. We bring it to the dealer and they change out the inverter under warranty and say it's fixed and send us on our merry way. Only problem is 2 days later the inverter burns out again. Now mind you this inverter is only powering our res frig. After the last go round I put a meter to all the wires to see whats going on and found that the male plug end that goes into the inverter was reading 120 when were plugged into shore power. I tested the inverter and it has 13.7 v going in from the batteries and 120 at the female receptacle. So even with the inverter is off this plug is back feeding the inverter with 120 and burning it out. Dealer is clueless on how it fix this and Keystone Tech support says that because the inverter was changed out they can't help. Anyone have any ideas as to why that male plug would read 120v going into the inverter and how to fix this

[DutchmenSport]

I don't know if this will help or not, but this is what the inverter system should look like. From what you are describing, it sound more like the transfer switch is either wired wrong, or it's defective.

[Roammer]

Thanks Dutchmen, That was my next thought after following the wires. I found the inline transfer switch and will be taking it apart to check out the wiring.

[Roammer]

By the way, thanks for the diagram. i couldn't find it online so that explained alot.

[RMcNeal]

It does sound like the transfer switch. On shore power, you should have 120 VAC from the inverter passed through from shore power. When not on shore power, or power failure, the 120 VAC should be supplied by the inverter from your batteries. The transfer switch will determine the source, shore power or battery. Sounds like it is not working properly.

[Roammer]

Thanks, hopefully thats the problem and it will be a simple fix.

[rohrmann]

I would think the 120 in and the 120 out, along with 12 volts on the DC side is correct. Your battery should be connected all the time unless you disconnect it. The inverter needs to see 120 coming in and should always have 120 on the load side, whether it is just passing through or being inverted inside the unit. If there is 120 coming in, internally the inverter should see that and should not be needing to make 120 volts from the 12 volt DC side. If the 120 volt source is lost, regardless of why, the inverter will see that and internally switch to make 120 volts from the 12 volt DC battery feed. I’m thinking something else is going on, either the unit is undersized or something else, but all the voltages stated are correct. Maybe there is a problem with the fridge that is causing the problem.

[DutchmenSport]

Originally Posted by Roammer

... i couldn't find it online so that explained alot.

Try Here. Then scroll down.

[66 Galaxie]

AC In and AC out are hooked up backwards on the transfer switch. Look at the cover on the TS-15 it should have a diagram. The wire from your breaker box goes to the AC IN.

* Shut off the breaker
* Turn off inverter.
* Unplug the Molex connectors between the transfer switch and the line and load.
* Turn on breaker. Whichever Molex connector has 120v power is the AC IN.
* Turn Breaker off.
* Connect AC IN Molex to corresponding AC IN on transfer switch.
* Connect AC out to Fridge line.
* Turn on breaker and see if Fridge runs.
* If so, plug the transfer switch back into inverter.

I can get you an inverter and transfer switch if you want to send me a direct msg.

[Roammer]

Thanks for your input, That's my plan. Going to the dealers tomorrow since they can't seem to figure it out

[Roammer]

Thanks, I figured it was the transfer switch but your advice will make the job easier.