Community Forums

denforent · 07-08-2021, 01:24 PM

My 01 Monaco Dynasty AC units trip the breakers on hot mid-day sessions. The Main unit trips more often than the rear unit... so I swapped the units at the breakers... they still trip. I do not run the units at the same time and I think the incoming voltage reads under 105 on a decent extension cord when this is happening... often as low as 103+ so I believe it's all low voltage issue. Would upgrading the breakers be a reasonable solution? The wire gauge to both units looks light to me but I'm a guitar picker so what do I know? These are original units (old) so??? Thanks for ideas

CRV2 · 07-08-2021, 01:31 PM

The best solution is to get an RV 50a (or 30a if yours is 30a) extension cord. When the voltage drops, the amps go up, so replacing the breakers isn't the answer. Not too mention, you really shouldn't run your A/C's on 106v or less and the lower you go the more damage you could cause to them. This is because as the volts go down, the amps go up, and as the amps go up the windings in the A/C compressor become increasingly hot, which in time can and does ruin the compressor which of course is expensive to replace (you have to replace the entire A/C), especially two of them and this is more likely to damage older A/C's but certainly will damage a new one as well running on low voltage.

So, new extension cord 10awg or heavier, monitor the voltage and don't run the A/C less than ~106v is my recommendation. ~CA

**Lt Dan** · 07-08-2021, 01:33 PM

When the voltage runs that dangerously low the amperage draw increases causing the breakers to trip. Running the A/Cs at that low of voltage drastically increases the chances of burning out a compressor or fan motor. Anything below 108 volts is beginning to get too low. What wire gauge size and length extension cord are you running?

KanzKran · 07-08-2021, 02:02 PM

Units are old, so may need a thorough cleaning. They can draw excessive current when the coils are loaded up.

The run capacitor(s) may also be tired, which may result in higher current. Start capacitors don't have any effect on running current once it's up to speed.

Circuit breakers with thermal trip triggers can and do age such that the threshold (time at overload) sags. It's better than them not tripping when they should. New replacements are very cheap, but if you replace them, get the same brand, series, and ampacity as the originals.

The cord is questionable, as you didn't state what it is exactly. You should be using a good quality 30A (or 50A) shore cord, with clean contacts.

US utility voltage is supposed to be 120V +/- 5%, and the NEC recommends* no more than 5% voltage drop in feeder and branch circuit wiring, which makes it 126-108V at the air conditioner's leads. Low voltage draws more current in constant-power loads like induction motors in air conditioners, and 103V is too low to start with, so that may be your problem right there.

Oh, and the skinny wire should end up in a sheath at some point, which will have wire gauge markings on it. 20A branch circuits to A/C units (an assumption, since it's old) should have 12 gauge wiring. If it's 14 gauge, it should be on a 15A breaker, and that could be a problem as that's too low for a continuous load the size of a typical A/C unit.

Lotsa things you can look into.

*It's recommended, but not code enforceable.

swduns · 07-08-2021, 02:07 PM

I'm not certain as to changing which breaker your referring to, the RV breaker feeding the AC unit or the house breaker the extension cord if fed from

Note that the circuit breaker is primarily an over current device protecting the wire that is attached to it. A 15A breaker should be used with #14 wire minimum, A 20A breaker should be used with #12 wire minimum, etc.

if you have #14 wire and change to a 20A breaker, then the wire could have more amps pulled through it than its rated for and potentially it could cause a fire. You should not arbitrarily change a breaker size unless you know what your doing.

Using a larger wire size extension cord to feed your RV from a house circuit will reduce the voltage drop and thus increase the voltage at the RV. It is fine to use a larger wire size on a circuit, just not a wire size not appropriate for the over-current protection.

Alternatively you can use a auto-transformer (aka a buck-boost transformer, hughes autoformer, voltage booster).

RustyTools · 07-09-2021, 05:28 AM

If you're getting low voltage on the 'incoming line' (which sounds like you might mean at the coach), it may not be the extension cord. What is the voltage at the pedestal or building outlet?

Xmcdog · 07-09-2021, 05:47 AM

As said above, you have a low voltage issue. Over heating of the compressor windings is opening the internal thermostat in the windings. This is a safety stat to protect the windings and should not be relied on for extended periods. Correct the voltage and you should be fine.

barmcd · 07-09-2021, 07:17 AM

Are you plugging your RV power cord into an extension cord? If so, how long is it? What gauge is it?

RamiDav · 07-09-2021, 08:14 AM

denforent, you are correct about it being low voltage. Continue with low
voltage and you'll be buying new A/Cs.

Changing breakers will probably be a waste of time and money.

If you are at an RV park you should move, at home find someone that can
help with properly sized wiring ( extension cord )

BTW what are you calling a decent extension cord and are you operating
on 30 amp or 50 amp?

Ray 03 Windsor

puttin · 07-09-2021, 09:26 AM

Besides a little a/c maint. get an Autoformer. All of your appliances will work more efficiently. Some of the best money I ever spent.

96 Wideglide · 07-09-2021, 09:39 AM

If your in a park, I'd be moving on before I did permanent damage to my A/C's.

Running them on that low of voltage is tempting fate

!

barmcd · 07-09-2021, 11:26 AM

Quote:

Originally Posted by denforent

My 01 Monaco Dynasty AC units trip the breakers on hot mid-day sessions. The Main unit trips more often than the rear unit... so I swapped the units at the breakers... they still trip. I do not run the units at the same time and I think the incoming voltage reads under 105 on a decent extension cord when this is happening... often as low as 103+ so I believe it's all low voltage issue. Would upgrading the breakers be a reasonable solution? The wire gauge to both units looks light to me but I'm a guitar picker so what do I know? These are original units (old) so??? Thanks for ideas

Did you guys see this? It sounds like he's plugged into an extension cord which will absolutely affect the input voltage if not sized correctly. 50 Amps needs an 8 gauge minimum, 6 would be better.

RamiDav · 07-09-2021, 11:59 AM

Quote:

Originally Posted by barmcd

Did you guys see this? It sounds like he's plugged into an extension cord which will absolutely affect the input voltage if not sized correctly. 50 Amps needs an 8 gauge minimum, 6 would be better.

I saw that and hope he will let us know what kind of extension cord it is.

Ray 03 Windsor