Three A/C Rig Question

[Captcolour]

A 15KBTU unit requires a 20A breaker and 12ga wire. You can not just replace a breaker with one of a higher amp rating to eliminate nuisance trips. To do so is asking for a fire and a denial of an insurance claim. The breaker is there to protect the wire, not the device.

Yes and verified as reported above that the wires are definitely 14 ga so breaker has to remain 15 amps. If the new A/C unit they are installing under warranty comes with the soft-start, then the 15amp circuit may work just fine. If the new A/C unit doesn't fix the problem, then I will push to have the wiring upgraded to 12 ga and a 20 amp breaker installed.

[Captcolour]

*Update* Just got the rig back from warranty work. They had to replace the AC/heat pump unit. Ran it for awhile when I got home and works fine on the 15 amp circuit. The new unit may have a soft start on it as it didn't seem to just blast on. Hopefully problem solved for the long term.

[BobLandry]

The new unit is at risk of failure. It may seem to run OK, but you are getting a voltage drop over the 14 ga wire and extended running on low voltage will damage the compressor. These units do not have the electronics to sense a low voltage condition and will continue running.

[Husker]

The new unit is at risk of failure. It may seem to run OK, but you are getting a voltage drop over the 14 ga wire and extended running on low voltage will damage the compressor. These units do not have the electronics to sense a low voltage condition and will continue running.

Nonsense, a voltage drop would not occur unless the unit attempted to draw more than 15 amps. In that case, the 15 amp breaker would trip, as it is designed to do. The unit cannot be pulling more than 15 amps because of the breaker, therefore, 14 gauge wire is sufficient.

[Tom Traveler]

Nonsense, a voltage drop would not occur unless the unit attempted to draw more than 15 amps. In that case, the 15 amp breaker would trip, as it is designed to do. The unit cannot be pulling more than 15 amps because of the breaker, therefore, 14 gauge wire is sufficient.

This may be just a bit more complicated. Circuits are designed to serve 80% of the rated capacity continuously. A 15 amp circuit shouldn't serve higher than a 12 amp load. The extra 20% is for starting currents, short term peaks, and safety margin. If Captcolour has Coleman-Mach 15 PS units in his 380FL (as we have in our 2021 380FL) they have a full load rating (continuous) of 11.8 amps on high fan, so you should be OK. However, you mentioned that this is a heat pump unit with heating capability. Under heating load, that unit is rated at 15.6 amps, well in excess of 12 amps and higher than the 15 amp breaker.

Have you tried the new unit with the heater yet? Grand Design should have put a 12 gauge wire and a 20 amp breaker on that circuit.

[Tom Traveler]

I've attached an excerpt from Airxcel's installation manual for Series 48xxx model RV air conditioners. It's clear this should be a 20 amp circuit.

[Captcolour]

This may be just a bit more complicated. Circuits are designed to serve 80% of the rated capacity continuously. A 15 amp circuit shouldn't serve higher than a 12 amp load. The extra 20% is for starting currents, short term peaks, and safety margin. If Captcolour has Coleman-Mach 15 PS units in his 380FL (as we have in our 2021 380FL) they have a full load rating (continuous) of 11.8 amps on high fan, so you should be OK. However, you mentioned that this is a heat pump unit with heating capability. Under heating load, that unit is rated at 15.6 amps, well in excess of 12 amps and higher than the 15 amp breaker.

Have you tried the new unit with the heater yet? Grand Design should have put a 12 gauge wire and a 20 amp breaker on that circuit.

This is just a heat pump (compressor only) without the option supplemental heater. So the 16 amps is not required for this unit. The original unit worked fine when operated as a heat pump. Never tripped the breaker and provided typical heat pump quality heat. Running the A/C would trip the breaker. I did not try the heat pump yet but don't expect it to be a problem.

As I said, if we start having problems again, then I will push GD to rewire to 12 ga and a 20 amp breaker. They replaced the unit under warranty so will see how it does.