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Old 05-21-2016, 10:43 PM   #1
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A/C Trouble

Hey everybody.
We have a 2005 29FBS. Happy with the most of it, but fighting an A/C issue. Doesn't matter if it's on a/c or just fan, but after it's been on a half hour or so, the fan loses its speed and eventually stops and throws a breaker. Since it doesn't seem to matter if the a/c is on or not, acts like the fan motor to me. Thoughts? Anybody? Thanks in advance.
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Old 05-21-2016, 11:40 PM   #2
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Could be the fan motor or a number of other things. If the unit throws a breaker, it's pulling more power than it should. If you're handy with a multi-meter, then you can do some electrical testing. If not, then you can do some rudimentary troubleshooting using your eyes and ears.

For electrical testing, check your amp draw on the power lead going to the AC. You should be able to get a loop multi-meter around the wire in your breaker panel to test for amp draw. If you have a 13.5K BTU, you should only pull 14 amps max during run. If you have a 15K BTU, you should only pull 16 amps max during run. Startup amp draw will be much higher, but only for a half-second or so. Any more continuous amp draw than the norm is an indicator something else is wrong, which will eventually cause the breaker to over-heat and trip.

Also, check your incoming voltage. Low voltage will do funny things, so make sure you have AT LEAST 110 volts coming in while the AC is running. Typical voltage should be around 120 volts. If the voltage is low, your amp draw will be higher which would cause the breaker to overheat and trip.

Last---or really first----make sure you're hooked up to a good power source using appropriately sized cables. If the AC works fine in one location and trips at other locations, then it's likely a power issue.

If you don't have a multi-meter or aren't handy with electrical stuff, you can still observe a few things to get an idea of what's going on.

Try pulling the front of breaker panel and running the AC. Once the breaker trips, feel the breaker to see if it's hot. If it's hot...like so hot it almost burns you, that's an indicator of either low voltage, low amps, or much higher amp draw than normal due to a malfunction with the AC unit.

Inside the camper, pull the AC cover and check your filters. If they are extremely dirty, they may inhibit airflow which would cause the motor to work harder to pull air, thus causing more amp draw and overheating the motor and tripping the breaker. While your filters are out, shine a flashlight on the coils to see if they have an ice buildup or if they are dirty. If there's ice, it could be caused by poor airflow or it could be caused by low refrigerant. Poor airflow is typically caused by dirty coils or dirty filters. Low refrigerant means it's time to replace the unit.

If able, you may want to get up on the roof and pull the shroud. Run the AC, and then observe it as it slows. Kill power, and then see if you can spin the blades with your hands. Note---you have to kill the power first or you'll wind up being known as Lefty...or Righty...depending on which hand you used to spin the blades. If the blades spin, then the motor isn't seized up. If the blades spin but make a noise, even a slight rubbing noise, then the motor bearings may be shot and you'll need to replace the motor.

Check the outside coils as well (rear of the unit). If the coils are extremely dirty or coated in ice, it could cause poor airflow. The motor would draw more amps and cause the motor to overheat and the breaker to trip. If dirty, clean and try again. If coated in ice, that's a potential sign of low refrigerant which means the unit would need to be replaced. It's also a sign of low airflow.

Bottom line, the motor spins for 30 minutes, so it's probably not bad. It may be weak...but not bad. My bet is on the coils being dirty which causes poor airflow, which leads to coil icing, which leads to more amp draw, which leads to the fan overheating as it draws more amps, which leads to the breaker tripping.

Not that I'm not an expert on this stuff. If you're uncomfortable doing troubleshooting, then I highly recommend taking it to a professional
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Old 05-22-2016, 12:51 AM   #3
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some faulty info

"If the coils are extremely dirty or coated in ice, it could cause poor airflow. The motor would draw more amps and cause the motor to overheat and the breaker to trip."

If you block the coils the motor does less work moving less air and the amps goes down.
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Old 05-22-2016, 01:00 AM   #4
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Motors can go bad many ways, some fan motors use a capacitor that can go bad, others use a shaded pole motor with no capacitor. If there is a noise associated with the fan motor running, it could be worn sleeve bearings allowing the rotor to contact the stator, this can slow the motor and cause it to trip it's internal thermal overload, shortly after the fan stops turning, the compressor can go into a hi pressure condition that could trip a breaker.
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Old 05-22-2016, 07:33 AM   #5
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After church this morning I'll open the unit up and check it out further. There's a good quarter inch of end play in the motor shaft. It had been built up with mud dobber nests but I've cleaned the entire unit. When I turn the fan on, when it hasn't been running for a while (cooled down), it runs great. After a half an hour with just the fan on (no a/c on), it slows way down, then stops and sits there and hums. Surely if I left it on, it'd throw the breaker again, but didn't leave it run. So the compressor for the a/c must be a separate motor, since I can hear it pumping even when the fan motor stops. Looks like a pretty easy swap on the motor, this afternoon I'll get the number off of it and find one. I'll let you all know what happens. Thanks again
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Old 05-22-2016, 08:32 AM   #6
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while you are looking at it, try to find any numbers you might see on a tag to identify the ac unit. That unit may just have a bad run capacitor on the fan motor. Yes, the compressor has a separate motor from the fan, located inside the compressors metal shell with no access, it's one unit (compressor and it's motor)
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Old 05-22-2016, 09:39 PM   #7
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Click image for larger version

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So this is the tag on the rooftop. Google says it's a Coleman. The fan motor is smoked.
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Old 05-22-2016, 09:50 PM   #8
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The fan, with or without a/c, after about ten minutes slows to a stop and sits there and smokes. Along with the fan motor is there anything else I should be checking? Or replacing? The capacitor? Probably inside the sheet metal box. Can't find a manual for this unit online. Thanks again.
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Old 05-22-2016, 11:32 PM   #9
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http://bryantrv.com/docs2/docs/rvp/rvp6789mech.pdf


If the motor has speeds, the 2 brown wires go to the capacitor
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Old 05-23-2016, 06:43 AM   #10
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Thanks! I'll get it ironed out this week.
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