Second AC isn't working

[TheDonger]

My 5th wheel has two AC units. The main one that is controlled by a wall thermostat works fine. The second unit is above the bedroom and has control knobs on it and doesn't turn on. It's like it doesn't have power but the breaker for it feels fine when I cycle it. It makes zero noise. It's a Coleman-Mach and I don't have a manual for it. Any troubleshooting advice is appreciated. Thanks!

[MrMark52]

Kill your shore power.

Open up the breaker panel and check all the wiring for anything showing signs of overheating and burns, and tighten all wire clamping screws (on breakers, neutral and ground buss bars).
Close the panel up, reconnect power.

Is your coach 30 amp or 50 amp?

Manuals are easily found with a little diligent searching - and it may be the one for yours can be found in the Files section, above.

Post back the model number of your A/C unit if you can’t find it.

Do you have a voltmeter, and do you have any idea of how to use it?

[TheDonger]

Originally Posted by MrMark52

Kill your shore power.

Open up the breaker panel and check all the wiring for anything showing signs of overheating and burns, and tighten all wire clamping screws (on breakers, neutral and ground buss bars).
Close the panel up, reconnect power.

Is your coach 30 amp or 50 amp?

Manuals are easily found with a little diligent searching - and it may be the one for yours can be found in the Files section, above.

Post back the model number of your A/C unit if you can’t find it.

Do you have a voltmeter, and do you have any idea of how to use it?

It’s a 50 amp. I’ve got a multimeter and can check the breaker connections but I don’t know where to check the other end. There doesn’t seem to be a model number on the exterior of the unit.

[Rockwood27]

Originally Posted by TheDonger

It’s a 50 amp. I’ve got a multimeter and can check the breaker connections but I don’t know where to check the other end. There doesn’t seem to be a model number on the exterior of the unit.

You need to take the outside cover off to find the model number.

Sent from my SM-A515U using iRV2 - RV Forum mobile app

[Tha_Rooster]

Originally Posted by TheDonger

My 5th wheel has two AC units. The main one that is controlled by a wall thermostat works fine. The second unit is above the bedroom and has control knobs on it and doesn't turn on. It's like it doesn't have power but the breaker for it feels fine when I cycle it. It makes zero noise. It's a Coleman-Mach and I don't have a manual for it. Any troubleshooting advice is appreciated. Thanks!

Do you have 30amp or 50 amp power?

[Captain8]

Typically with AC units there's a power wire going from the vent duct to a control module on the side of the roof AC box. Find this wire and check for voltage, either at the control box at the roof top or maybe under the vent if there's an electrical box.

If its getting 120V power make sure there isn't any other wires leaving that box. There could be 12V thermostat/load shedding device somewhere on the coach.

You also could have an issue with your 50amp as typically they'll put each AC on its own leg. You can test your plug to make sure you have 120V on each leg.

[TheDonger]

Originally Posted by MrMark52

Kill your shore power.

Open up the breaker panel and check all the wiring for anything showing signs of overheating and burns, and tighten all wire clamping screws (on breakers, neutral and ground buss bars).
Close the panel up, reconnect power.

Is your coach 30 amp or 50 amp?

Manuals are easily found with a little diligent searching - and it may be the one for yours can be found in the Files section, above.

Post back the model number our A/C unit if you can’t find it.

Do you have a voltmeter, and do you have any idea of how to use it?

Ok I’ve got a model number and found some suspicious loose wires. Can’t find my multimeter so I haven’t checked for power. The black/green/white wires in the picture go up top to the fan and compressor.
Model number 48204A876.

Any clue about the loose wires?

[MrMark52]

Originally Posted by TheDonger

Ok I’ve got a model number and found some suspicious loose wires. Can’t find my multimeter so I haven’t checked for power. The black/green/white wires in the picture go up top to the fan and compressor.
Model number 48204A876.

Any clue about the loose wires?

What loose wires? All I see are the black/white/green as you mentioned.

[TheDonger]

Forgot to add this pic

[TheDonger]

Originally Posted by MrMark52

What loose wires? All I see are the black/white/green as you mentioned.

The black white and green aren’t attached to anything. They’re loose.

[MrMark52]

Originally Posted by TheDonger

Forgot to add this pic

Attachment 394393

Originally Posted by TheDonger

The black white and green aren’t attached to anything. They’re loose.

This helps!

That Romex is what powers that unit, and connections should be made

Black to black

White to white

Green to bare wire (ground)

Is this a new 5th wheel to you? Those wires don’t just come loose and cap themselves.

[TheDonger]

Originally Posted by MrMark52

This helps!

That Romex is what powers that unit, and connections should be made

Black to black

White to white

Green to bare wire (ground)

Is this a new 5th wheel to you? Those wires don’t just come loose and cap themselves.

10 years old and new to me. I’m hoping there isn’t a reason that they’re unhooked.

[K7JV]

Curious, to be sure. You have the Romex with a black, a white and a bare as "Captain8" described. You also have the four un-terminated wires in the middle picture, above, that appear to be a part of a typical 120 volt circuit.

If it were me, I would try turning off that A/C's breaker, and it would be best if you could verify that no voltage is present on the Romex cable between the black and either the white or the bare conductor. If you can't confirm that, it would be best to turn off or unplug your shore power source. Then I would connect white to white, black to black(s) and bare to green in that group of un-terminated wires.

Turn on the power source and/or the breaker, with everything still opened up the way you have it, and see what works or doesn't work. Worst case, if the A/C unit is failed, or has a short in it, the breaker should protect you and everything.

If you try that, let us know. It is curious. It does not look the way the manufacturer would have left it. Rather, it looks like someone took it out of service for some reason. Someone told me once that all electrical devices have a supply of smoke hidden in them. As long as the smoke doesn't leak out, you're good. Hopefully you won't let any of the smoke out when you power it up. ��

[TheDonger]

Originally Posted by K7JV

Curious, to be sure. You have the Romex with a black, a white and a bare as "Captain8" described. You also have the four un-terminated wires in the middle picture, above, that appear to be a part of a typical 120 volt circuit.

If it were me, I would try turning off that A/C's breaker, and it would be best if you could verify that no voltage is present on the Romex cable between the black and either the white or the bare conductor. If you can't confirm that, it would be best to turn off or unplug your shore power source. Then I would connect white to white, black to black(s) and bare to green in that group of un-terminated wires.

Turn on the power source and/or the breaker, with everything still opened up the way you have it, and see what works or doesn't work. Worst case, if the A/C unit is failed, or has a short in it, the breaker should protect you and everything.

If you try that, let us know. It is curious. It does not look the way the manufacturer would have left it. Rather, it looks like someone took it out of service for some reason. Someone told me once that all electrical devices have a supply of smoke hidden in them. As long as the smoke doesn't leak out, you're good. Hopefully you won't let any of the smoke out when you power it up. ��

Tried it and got nothing