AC Issue

This website has been my best source of information and has really helped me get started RVing. I really appreciate the comments and information given.

I have a 2015 2910D. We had relatives in town and needed the extra bed so we parked the RV in the driveway as we have done many times before. I hooked it up to shore power and city water as usual. When my guests started the AC (I’m in South FL - 86 degrees today) the breaker blew in the house.   It never happened before so I reset and tried again with the same result. So I unplugged the shore power and fired up the generator and started the AC. It (AC) groaned for a few seconds and then the generator started sputtering and died. Fired the generator back up and tried again with the same result. The generator is fine and works perfectly until I fire up the AC. Seems the AC is trying to pull too many amps – not good. Any thoughts?

I've only had the unit about 6 months and bought a warranty with the purchase. So I'm not worried so much about the cost but the aggravation is aggravating,

The A/C alone will pull close to 15+ amps on startup so unless you have a 30amp outlet to plug into, it can easily blow the breaker on a standard household outlet (15amp).

In addition, if your coach batteries are heavily discharged, the charger can also draw a lot of power... Thus between the 2, overloading the generator also.

Were I you, first thing I would do is look at the state of charge on the house batteries.  If they are real low, I would let the converter charge them for several hours before attempting to run the a/c.

There are other possibilities too, the a/c compressor could be frozen or shorted but to be honest, that's unlikely... Although not impossible.

A crooked a/c unit just might be sensitive to a startup.  You have guests inside so I assume you are already level, but I had to say it anyway.

I would try to get the generator running a while with NO load until warmed up and running smoothly.  Then try starting the a/c.  If you can get the two working together, then try shore power after you have cooled down the interior.

For shore power, ideally you would use the PC-supplied 30 amp cord with a stubby adapter direct to a regular 20 amp outlet in your garage or house.  Hopefully you have a 20 amp outlet in close proximity.  A 15 amp house outlet is bordering on being insufficient, especially if you have other items in the house actively on that same circuit.  If using an additional extension cord after your PC cord, it really needs to be 12 gauge and short as possible.  I carry an extra 30 amp extension cord in our PC for just this reason.  You would be surprised how a regular orange utility extension cord adds enough resistance to interfere with a/c start-up, resulting in a tripped circuit breaker.

I appreciate the feedback.  I will double check everything but I have used it at least five times before parked at the same spot in my driveway; same cord, same house outlet, same everything.  I’ll try again tomorrow and will let the generator run for an hour before I try. The battery indicator gauge says that the batteries are fully charged, but I will visually inspect and check them as the gauge might not be the best indicator. I haven’t even looked at the batteries as the dealer assured me that they did a full inspection.

While plugged into shore power turn on the a/c fan manually with the thermostat set high so the a/c unit does not start.  With the fan running move the thermostat until the a/c comes on.  That will reduce the start up amps and hopefully start the a/c. 

Check the oil in your generator.  The generator should start the a/c.  Can you run the convection oven? That is another large amp draw.

Ron

A household 20amp receptacle/plug have the 2 power carrying blades at right angles to each other.  15amp blades are parallel to each other.

See attached pictures of 20amp "household" plug and socket.    Normal household duplex outlets are rated at 15amp although I have seen where people have replaced the 15amp breaker with a 20amp breaker.  Which is not a safe practice.

While plugged into shore power turn on the a/c fan manually with the thermostat set high so the a/c unit does not start.  With the fan running move the thermostat until the a/c comes on.  That will reduce the start up amps and hopefully start the a/c. 

Check the oil in your generator.  The generator should start the a/c.  Can you run the convection oven? That is another large amp draw.

Ron

Ron/Sarz has some great tips. 

The other Ron

So I drove the RV down to AutoZone and had the batteries tested. They are in good shape and fully charged. Got home and started the generator. I noticed that the microwave didn’t come on immediately as before. After about 10 seconds the microwave and lights came on and everything worked fine.  I ran the generator for about 40 minutes and then turned on the AC. Again the generator died. I turned on the fan and gradually the AC. The AC unit sounds like it wants to start but the generator dies. I restart the generator and 10 seconds later everything works except the AC. I’m taking it in Monday and I’ll post the results.

Thanks for the suggestions.

Make sure the storage switch is not off with the batteries disconnected.  Reset the switch.  With the generator on check voltage at the inverter behind the drivers seat.  Voltage should be 12.8+ if switch is on and generator charging battery.  If a/c does not start you have done all you can.

Don’t forget to check generator oil frequently.  It uses oil while running.

Ron S

A household 20amp receptacle/plug have the 2 power carrying blades at right angles to each other.  15amp blades are parallel to each other.

See attached pictures of 20amp "household" plug and socket.    Normal household duplex outlets are rated at 15amp although I have seen where people have replaced the 15amp breaker with a 20amp breaker.  Which is not a safe practice.

Don, that's really only true of newer homes.  The T-shaped 20 amp plug is a fairly recent addition.  For many years, the same recep was used on both 20 and 15amp 110 volt circuits.  You really need to check the breaker box to determine the amperage of a given circuit in most homes, but as a former electrician, I can give you some hints.  Kitchen, bathroom, utility room, and garage circuits are normally 20 amps, and many local codes even limit them further to two recepticles per circuit. Outside GFI receps are also a pretty good bet because they are often the same 20amp GFI circuit that also feeds a bathroom or kitchen. 

Quote from: donc13 on November 07, 2019, 08:26:34 pm

A household 20amp receptacle/plug have the 2 power carrying blades at right angles to each other.  15amp blades are parallel to each other.

See attached pictures of 20amp "household" plug and socket.    Normal household duplex outlets are rated at 15amp although I have seen where people have replaced the 15amp breaker with a 20amp breaker.  Which is not a safe practice.

Don, that's really only true of newer homes.  The T-shaped 20 amp plug is a fairly recent addition.  For many years, the same recep was used on both 20 and 15amp 110 volt circuits.  You really need to check the breaker box to determine the amperage of a given circuit in most homes, but as a former electrician, I can give you some hints.  Kitchen, bathroom, utility room, and garage circuits are normally 20 amps, and many local codes even limit them further to two recepticles per circuit. Outside GFI receps are also a pretty good bet because they are often the same 20amp GFI circuit that also feeds a bathroom or kitchen.

FWIW, this was the type of receptacle that we had for the 20 amp service, and known as "The one you can plug the AC into" plug.    It was on its own circuit, and near the window. Might be a 'Florida Thang'.The larger window shaker AC's had a plug that one side was vertical, one horizontal. You could use the outlet for either 15 or 20, but only use the AC in that outlet.  I think todays window AC's are a lot more efficient and use regular 15A plugs.

Actually, THIS is the "one you plug the A/C into".  It's a 20amp 220V recepticle.  Note the horizontal hot-side blade.  Whatever you do, do NOT plug your PC into a plug that looks like that one!

I've never heard of running a special 20a 110v circuit just for a window unit.  110v window units usually don't pull 20 amps.  I guess someone could wire a dedicated 20am circuit for a 110v window unit if they wanted to.  But the whole reason they even make 110v window units is so you don't need a dedicated circuit to plug it in.

   Dunno. I know what was there, and was 110V.  Kissimmee / St Cloud Fl c1992-8. Houses subdivided into apartments. Guessing 60's to 80's construction? No central HVAC.  Huge older window shakers. They had the odd plug so they only worked with that outlet.  We had a Sears one.     18,000 btu IIRC, but that was MANY beers and several years ago... 


My plasma cuter uses the 220v 20a you picture, familiar with that. 

UPDATE:  Back from RV shop. Tech says "High voltage readings out of control board and fan has very low speed. Found bad run capacitor and control board. Replaced capacitor and control board with new and tested all functions, all working as they should". Total cost was $418 and warranty covered all but $30. I'll take that any day. 

Thanks for all the input.