Rear AC - no amp use showing?

[J&SW]

OK, hope someone can explain this one. Went out to the rig to put the generator through its paces between vacations. I run it every once in awhile just to keep it exercised. Ran the front AC, and the main panel shows 9 amps use. Turn the front off and turn the rear on, and it shows . . . 1 amp use. The rear AC does run, and seems to be fine, blowing cool air. But, it does not show up as using any amps on the panel.

I then turn off the generator and hook up to external 120, and run the rear AC, and it shows 9 amps use.

Any explanation for this?

[John Mo]

I'd say you have a switch somewhere that selects where the rear air condition draws it's power. This is how mine is, but I haven't confirmed what the meter does in the two switch positions. On mine, the power cord plugs into a socket from the generator and the switch gets set to generator. This selects a separate circuit from shore power line for the rear air, though, again, I don't know if this separate circuit is independent of the meter. It seems like it would need to be. If I were to flip the switch to shore power and run the rear air, I would expect to see it register on the meter.

[Chief]

If possible, try running both AC's at the same time while monitoring the current draw. If the draw jumps to say 17-20 Amps, then both AC's must be operating properly.

[bouser]

The amp meter only reads the front ac on gen. It reads both on shore power.

[wa8yxm]

That one is easy.. You have a 30 amp rig right?

The Front A/C runs through the EMS, but on a 30 amp rig the rear A/C runs off the EMS only if it is selected AND you are on shore power.

If you are on generator power it's powered by the generator directly, In many cases you could even turn off the circuit breaker that feeds it and it would keep running (There is another breaker, the 20 amp one, on the generator that is protecting it when the generator is running)

But the reason it did not draw power through the EMS is the auto-transfer switch bypasses the EMS for the Rear A/C.

Also, you can run both of them at once on the generator since .. See above.

That is also WHY they do it that way in case you are wondering.

[doc]

Hmmm???

On 50 amp service the Energy Management System (at least on our previous Itasca Horizon) did not show the amperage being used. It did on 30 amp service. This was to help you manage loads and not overload circuits on the 30 service.

[J&SW]

I LOVE this group! Thanks for the quick and useful info.

Check - one more mystery solved.