AC kicks breaker every few minutes BUT only when above 100 degrees

farrelltravis · 08-09-2011, 08:36 AM

Hi all! I am still new here, but thought this forum may be able to help.

For starters - The 5er is currently at an RV park and has been there for several months now. The AC has always ran fine, up until recently. We are in Oklahoma, so the heat has really been harsh lately.

Now in the past few weeks, when the temperature is above 100 degrees, the AC kicks the breaker every 2 to 5 minutes. However, when the sun goes down and/or the temperature drops, it will run fine. Again, nothing has changed, just the outside temperature.

Any ideas on why it is doing that???

Thanks in advance!

jimh · 08-09-2011, 09:09 AM

the heat isn't helping. the higher the temp, the more amps the compressor will need. (freon requires a higher pressure to condense as ambient temp goes up. compressor requires more energy to build the extra pressure).
my suggestion would be to go on top, take a water hose, and wash back thru that condensing coil (with the unit down). u don't have to pull any covers to do that. air flow is pushed out thru the coil so u could get a build up on the inside. it may help but won't hurt anything.
u could also be experiencing lower than normal voltage at the campground. that one i can't solve. the breaker may also be weak.

farrelltravis · 08-09-2011, 09:13 AM

Yeah, I think a ampage loss is what is happening too. I can't see how there could be a mechanical problem, but I wanted to get the opinions of people here on the board.

I am thinking about maybe testing the amps at the breaker when it cuts out.

When you say (with the unit down) do you mean powered off? Sorry about that, just didn't quite understand.

Thank you very much for the response, though!

jimh · 08-09-2011, 09:37 AM

just meant not running. u would be pushing water against the air flow.
i know home units pull the air in but it seems like when i went on top with mine while it was running, it pushed air out thru the coil.
should be able to check voltage from an outlet on the inside of the camper. that way u will be seeing what the a/c sees. every plug and adapter in the circuit between the shore power and the trailer is a potential voltage drop.
come to think of it, u may want to unplug and check and see if ur connections are showing heat. may just be able to feel of then and tell. i camped at one park, plugged in 50 amp. when i left, one of my plugs on the cord was discolored and the rubber was soft. cleaned my plug and haven't had the problem sense so suspect the contacts in the shore power socket were loose (causing some arcing).
if u have 30 amp, checking the voltage inside the camper is easy. if ur on 50, u may have to check several outlets to make sure u get on the same side the a/c is pulling from.

farrelltravis · 08-09-2011, 10:11 AM

Yeah, I will have to check that, thank you.

Kpinto · 08-09-2011, 10:36 AM

Quick question. You mentioned it is at a park and has been there. Is the camper under a cover? If so how close is the roof from the AC unit? I have seen this before, not enough clearence and the heat from the tin roof causes problems with the unit.

Bilcin · 08-09-2011, 10:38 AM

I had the same problem a few weeks back. The CG I was at had only 30 amp service and it was an older CG. Air worked perfectly until EVERYONE in the park was using their ac also. My breaker shut off every 10 -15 minutes before I finally left it off and went to the pool. Other campers who are seasonal renters told me that a slight drop in amperage from everyone using their ac will heat up the compressor and this will trip the the breaker, and some campers with regular refridgerators said some were damaged because of the drop in amperage. When the sun started setting the ac was on again w/o any problems. Does this happen with 50 amp TT also or is it mainly the 30 amp TT?

farrelltravis · 08-09-2011, 10:52 AM

Quote:

Originally Posted by Kpinto

Quick question. You mentioned it is at a park and has been there. Is the camper under a cover? If so how close is the roof from the AC unit? I have seen this before, not enough clearence and the heat from the tin roof causes problems with the unit.

The 5er is parked outside with nothing above it, just open air.

jimh · 08-09-2011, 10:54 AM

i haven't experienced it yet. just haven't been to the right park i guess. i have a 50 amp connection but am not always able to get 50. last campground i was adapted to 30 and the campground was full. was told voltage had been a problem for others the prior year. i had no problems.
i would think u could have the same voltage problems on 50 as 30. only difference is u would hope the 50 service was newer and wired adequately. i would suspect when some of the 30 amp services were built, the demand wasn't nearly as great as it is today.

farrelltravis · 08-09-2011, 11:03 AM

Bilcin, I can't speak for 50 amp, but ours is a 30 amp 5th wheel.

It has really been hot around here lately. Here in Oklahoma, we just set a new nationwide record for the highest average temperature for a month. The average for July was 89.1. That doesn't sound high, but it is the average which includes the evening temps also. That is actually higher than any of the 50 US states for any month of the year. Yesterday was 110!!

farrelltravis · 08-09-2011, 11:06 AM

So, it sounds as everyone agrees that it is a CG electrical issue, and NOT an AC or inside the trailer mechanical problelm.

Thats puts me at ease a bit......until it is 130 degrees in the trailer!! Oh, the fun!

jimh · 08-13-2011, 09:32 PM

generally, if it is a problem in the park, u won't be alone.
that probably doesn't make u any cooler....

skgeorgy · 08-13-2011, 11:24 PM

Breakers exist in trailers in houses and trailers to protect the wiring inside of them from overheating and starting a fire. They are not for protecting devices from overloading. An a/c breaker shouldn't trip due to it working hard. There are fuses and other things in the device to prevent it from over loading. An a/c unit is rated for 20 amps shouldn't be able to run at more than that without the motor overloads kicking in first. The a/c unit will only cool the ambient air to I think around 20-25 degrees cooler than ambient air. So if it is 105 degrees out. You will be lucky if your trailer can get to 70 or 75 degrees. I have to agree that there is probably something wrong with the campground supplying the power. My guess is power surges and or voltage drop. There is no such thing as amperage drop.
Voltage drop can occur if demand is too much from the source or the campground supply.
Sorry if I rambled but I am a journeyman electrician and trying to explain it without getting to technical. Sorry if it doesn't make sense. Talking is easier than typing.

skgeorgy · 08-14-2011, 12:25 AM

Just though of a way to simplify the a/c overloading thing. If one covers the nozzle of a vacuum you notice the motor start of over work. Usually on fixes the obstruction before you break the vacuum. If you don't clear the obstruction the vacuum would burn out way before the breaker trips. Another way to look at is at home if one has a in window air conditioner. If the unit is too small for the room it is in, the room stays warm. No matter how hard the unit works. It could be going 24/7 trying to keep the room cool. The unit would fail before the house breaker trips. Electrical appliances are designed to not exceed its source capacity. If it is output is 15 amps it will not exceed 15 amps.
Hope this helps.

kablair · 08-14-2011, 09:43 AM

At the risk of trying to over-simplify....

Any electrical device, such as an A/C unit, requires a relatively constant amount of *power* to do the work asked of it. For electricity:

Watts (power) = amps x volts

Since volts is typically considered a constant, then devices can be rated according to their amp demand; which is how breakers are sized. This works 99.9% of the time.

However, if the voltage drops, then to maintain constant *power*, the amp draw must rise. Small changes usually go unnoticed as most devices have some tolerance to different voltages.

But, if the voltage drops enough (such as when trying to supply a whole park full of AC units), then the amp draw through your post will go up and can exceed your breaker rating.

An earlier post noted that, at higher temperatures, refrigerant requires more work (power) to compress it. I hadn't thought of that before, but if an electrical device is asked to do more work, then it will draw more amps through the post.

kbrown1075 · 08-14-2011, 10:09 AM

Attempted to delete my post with no luck. Corrected post follows.

skgeorgy · 08-14-2011, 10:10 AM

Thanks kablair for that. It was stuck in the back of my head and couldn't type it out. lol. Late night insomnia postings.

kbrown1075 · 08-14-2011, 10:12 AM

Quote:

Originally Posted by kablair

At the risk of trying to over-simplify....

Any electrical device, such as an A/C unit, requires a relatively constant amount of *power* to do the work asked of it. For electricity:

Watts (power) = amps x volts

Since volts is typically considered a constant, then devices can be rated according to their amp demand; which is how breakers are sized. This works 99.9% of the time.

However, if the voltage drops, then to maintain constant *power*, the amp draw must rise. Small changes usually go unnoticed as most devices have some tolerance to different voltages.

But, if the voltage drops enough (such as when trying to supply a whole park full of AC units), then the amp draw through your post will go up and can exceed your breaker rating.

An earlier post noted that, at higher temperatures, refrigerant requires more work (power) to compress it. I hadn't thought of that before, but if an electrical device is asked to do more work, then it will draw more amps through the post.

Thanks for this post. As I was reading the thread, this is all I had in mind. At the house, we kept blowing a capacitor in the DW's wine cooler and the DirecTV receiver would reset every once in a while. I took my Digital Volt Meter (DVM) and was measuring 108VAC (RMS). Problem found, now the fix. I called one of my buddies from the City Utilities and told him what I found. They came right over and what they found was that the transformer that we were feeding from had 5 houses on it and the transformer was over 40 years old. The transformer was there before everyone had AC in their houses, so when everyone was running their stuff, we were getting "brown power" (low voltage) which appliances needed more amps to produce the needed power. The wine cooler's cap couldn't handle the amp draw and would pop. The sat receiver would start to have a problem around 110VAC (I was familiar with the sat tv issue from my marine electronics days). The city utilities upgraded the transformer to a 35KW and now no more brown power. When it is cool out and there isn't much draw, I read about 122VAC at my new UPS with voltage input/output display and about 116VAC when it is hot and all the houses are running AC.

One other thing that can cause the breaker to trip in different places is a weak contact in the plug at the CG pedestal. If you have to use an extension from the standard 25 ft power cord, that can also cause a voltage drop, hence higher amperage draw. Gotta love Ohms and Watts. Great Laws (Ohm's law and Watt's Law)

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