Question Turning on both AC kills generator. Runs fine when plugged in.

[Dona40]

I checked the acs each running with the microwave and it didn’t die. Is the back air only supposed to turn go through the 20 amp breaker ? I shut off the 30 amp breaker and only the front air would come on. Nothing else. I shut that off and turned on the 30 amp breaker. The front and back air would each work individually, all outlets and microwave. Maybe both airs are going through the 30 amp instead on one on each breaker?

Each A/C unit has it's own breaker circuit. The microwave (1100 watts) won't simulate the current of an A/C unit (2200 watts start up). Maybe hook up some electric heaters? They are usually around 1500 watts. Try to simulate around 4000 watts. Other than that, I don't know what else to check without looking at it. Did you say both A/C units work while plugged in to shore power?

 

[KellieB]

Each A/C unit has it's own breaker circuit. The microwave (1100 watts) won't simulate the current of an A/C unit (2200 watts start up). Maybe hook up some electric heaters? They are usually around 1500 watts. Try to simulate around 4000 watts. Other than that, I don't know what else to check without looking at it. Did you say both A/C units work while plugged in to shore power?

Yes both work on shore power. With generator on I shut off the 30 amp breaker and 1 air would work and nothing else. Then I switched the 30 on and 20 off. Both airs would come in individually. I thought that one of the airs would only work on each breaker? Both will work on the 30. When I used the microwave with each individually it said I was using 25 amps. But if I turn on both airs, with nothing else on The generator goes off. It used to run both airs okay. Maybe both airs are coming through the 30 amp together and killing the generator. Had new breakers put in last summer. Could the breakers be in wrong? Or the one air for some reason not going off the 20 amp, when both are turned on. The aco solenoid behind the fuzzes inside Buzzes and lights up and generator dies.

 

[Bob K4TAX]

The solenoids in the pictures are usually used in the 12V circuit to engage the starter on the generator. The relay in the center picture {to the right of the dog} is typically used to switch the AC line from the generator to shore power. As to arcing, it is not unusual for one to observe an arc within relay contacts when switching with a load. The relay as pictured appears to switch both the Line and Neutral side of the load between the AC shore power and the generator. That relay is switched with power from the generator, thus when the 2nd AC is turned on, the voltage drops, the relay buzzes, and the contacts will arc. The pictures with the terminal strips and fuses are all DC circuits.

With one AC running, typically running amps would be 11 to 13 amps. When the 2nd AC is turned on the starting current can easily be 20+ amps. It could be the resistance in the circuit is higher than expected and thus the voltage drop during the increased starting current drops the voltage, thus the current demand goes up. The generator at 5500 watts is capable of 45 amps but this is with resistive load. The starting capacitor on the AC may be old enough that the starting current is higher than normal. Only current measurement at the AC unit will determine this.

The bottom line to this.......... one needs to measure the starting current and running current of each AC unit. Then measure the voltage at the unit during starting and running. If the voltage drop is excessive during starting, likely so running the generator because when it "sees" a voltage drop or current increase the throttle has to open up, feeding more gas, to develop more power. This can be a period of low voltage while the generator catches up with the load. The shore power system has a much higher range of dynamic load as compared to the generator.

It will take some serious diagnostics to identify the issue and not just throw parts at it.

 

[Dona40]

Since you had some electrical work done, I would double check the polarity of the A/C circuits as most 115 AC devices will work with reversed wires. You could be getting shorting between the units coming from the gen. Just a thought.

 

[KellieB]

The solenoids in the pictures are usually used in the 12V circuit to engage the starter on the generator. The relay in the center picture {to the right of the dog} is typically used to switch the AC line from the generator to shore power. As to arcing, it is not unusual for one to observe an arc within relay contacts when switching with a load. The relay as pictured appears to switch both the Line and Neutral side of the load between the AC shore power and the generator. That relay is switched with power from the generator, thus when the 2nd AC is turned on, the voltage drops, the relay buzzes, and the contacts will arc. The pictures with the terminal strips and fuses are all DC circuits.

With one AC running, typically running amps would be 11 to 13 amps. When the 2nd AC is turned on the starting current can easily be 20+ amps. It could be the resistance in the circuit is higher than expected and thus the voltage drop during the increased starting current drops the voltage, thus the current demand goes up. The generator at 5500 watts is capable of 45 amps but this is with resistive load. The starting capacitor on the AC may be old enough that the starting current is higher than normal. Only current measurement at the AC unit will determine this.

The bottom line to this.......... one needs to measure the starting current and running current of each AC unit. Then measure the voltage at the unit during starting and running. If the voltage drop is excessive during starting, likely so running the generator because when it "sees" a voltage drop or current increase the throttle has to open up, feeding more gas, to develop more power. This can be a period of low voltage while the generator catches up with the load. The shore power system has a much higher range of dynamic load as compared to the generator.

It will take some serious diagnostics to identify the issue and not just throw parts at it.

Yes, I figured it has to be someone that knows a lot about electrical issues. I’ve called a couple of repair places, but they don’t act too knowledgeable. I thought the airs each ran on a separate breaker. Is it normal for both to work on the 30 amp. When I tested them they would both come on when on the 30 amp breaker. I’m trying to know as much as I can before getting someone to look at it.

 

[Dona40]

Each of my A/C units have a dedicated 20A breaker. I think that's how it should be. Not sure about a 30A service.

 

[KellieB]

Each of my A/C units have a dedicated 20A breaker. I think that's how it should be. Not sure about a 30A service.

I’m talking about the breakers on the generator