Rv ac trips breaker on hot days

Topic: AC tripping in extreme heat...need suggestions!

Posted By: bren0035 on 07/06/17 08:31pm

Ok, I'm new to this forum and usually don't need to ask for this type of help as I have a good group of people that have been trailering for many years and are good at answering my questions. I'm at a loss and wanted to see if anyone on here had some ideas. Here are the details for all you trailer Dr. out there.

I just bought a used 2007 KV Sportsmen (38 ft) travel trailer. We restored the interior of the trailer and before going out camping I checked everything I could, i.e., fridge, lights, water, toilet, sink, etc. We bought this trailer to use in Havasu/Parker Dam, CA. The temps in the summer are constantly in the 110-118 range so it gets hot and stays hot all summer.

I have two AC units on my trailer. The guy I bought it from installed the second (rear) AC on its own seperate breaker and upgraded the electrical to 50amps. THE PROBLEM I HAVE IS I CAN'T SEEM TO KEEP THE MAIN AC TO STAY ON!!! The back one will stay on all day and night and blows freezing cold air, but the main one has issues running during the day, BUT will stay on at night with little issues. It trips the breaker around 11-12pm during the day and will keep tripping every time I reset it. Once it gets to be around 8-9pm at night and the sun is down, I can flip it back on and it usually stays on all night or sometimes will trip once or twice, but then will stay on all night and blow cold air.

I thought it might be pulling too many amps because it was dirty so I got up on the roof the following trip and cleaned it real good. I also replaced the breaker. Still trips! I placed a fan on the internal breaker box thinking that maybe the breaker is getting over worked and hot, but it still trips. I'm thinking it has to do with heat as it trips right when it gets extremely hot, but why would it still trip if the AC inside was still cold? Will the AC trip if the external unit get too hot? Why does the back one stay on all day and have no issue?

I've also tried turning the back one off and letting the main one work and pull amps by itself, but the same thing happens. It's hard to trouble shoot because at one point the AC will work for many hours without problem.

I've had some people say to try putting that unit on a 25-30 amp breaker and put it on the bottom of the box so there's some space in the breaker box and allows for better ventilation. I'm fearful that I could allow the AC to fry itself, but believe the idea was that the AC was trying to run harder to keep up with the hotter temperature. Again, why would the back one have NO issue at all. They are both Coleman.

Sorry for the long post, but I need to figure this out or staying out there will continue to be a huge frustration for us. The back one can't keep the trailer cool during the late afternoon.

Thoughts.

Posted By: krobbe on 07/06/17 09:12pm

Can't really troubleshoot it without knowing the voltage and current when it trips. When voltage decreases, current increases. The breaker trips when the current goes high enough to exceed the trip rating of the circuit breaker. Don't change the circuit breaker with a higher rated one. They are there to protect the wiring from overheating and burning down the trailer. If voltage and current is normal for that circuit, replace the circuit breaker with the same current rating. They do wear out. Especially when they experience a few overload trips.

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Posted By: jyrostng on 07/06/17 10:06pm

Those units blow the air through the back coil from the inside out. The part of the coil that gets dirt on it is on the inside facing the fan. When the ac unit isn't able to blow enough of the heat out, it makes too much pressure, this overloads the compressor, causing the amps to rise. Make sure the rear coil is clean and the fins are straight and not folded.

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Posted By: yillb on 07/06/17 11:36pm

jyrostng wrote:

Those units blow the air through the back coil from the inside out. The part of the coil that gets dirt on it is on the inside facing the fan. When the ac unit isn't able to blow enough of the heat out, it makes too much pressure, this overloads the compressor, causing the amps to rise. Make sure the rear coil is clean and the fins are straight and not folded.

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Why Is My RV air conditioner tripping the breaker?
Why does my breaker trip when it's hot outside?
Why does my AC trip in the summer?

Listen to this guy, almost guarantee that's your problem.

Posted By: FrankShore on 07/07/17 04:37am

Could you go back to or call the former owner? He should have some sort of trick that will get it up and running. Or if dealer bought, call the dealership and explain your problem, etc

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Posted By: colliehauler on 07/07/17 06:02am

yillb wrote:

jyrostng wrote:

Listen to this guy, almost guarantee that's your problem.

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Posted By: dfletch on 07/07/17 06:06am

I had a similar problem on my old MH. Unit would draw more current on hot days. I got a gallon of coil cleaning fluid from commercial AC supply store diluted it as directed and used a garden sprayer. Got on the roof removed the Cover and soaked the coils then flushed with fresh water. You would be suprised all the junk that came out of the coils. Used shop back to suck up excess water and junk. AC worked much better after that.

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Posted By: dodge guy on 07/07/17 08:01am

I don't have an issue with the breaker tripping, but the last few years I noticed the A/C wasn't working as good as it was the first few years. So I got up on the roof and opened up he A/C and found about a quarter of the coils in the corners covered in gunk. I brushed them, blew it out from the back side and brushed some more then blew it out some more. Then I rinsed them out. It was loaded with dust in between the fins/tubes. I hope it's back to normal where it will cool the entire trailer on a 95deg day. I'll see in 2 weeks when we go out west!

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Posted By: jyrostng on 07/07/17 09:24am

When cleaning the rear coil, protect the fan motor from water spray. The bottom of the motor is open, too much water in the motor and it will short out. A plastic bag around with tape usually protects it.

The sheetmetal shroud around the rear fan is usually attached with screws and you can slide it forward to get to the rear coil better, you"ll be amazed sometimes that the unit can work at all as stopped up as the coil is

Posted By: humblerb on 07/07/17 10:30am

Had the same issue a couple of years ago (trailer is now 5 years old). Replaced the breakers, never had another issue. Got to believe factory are cheap (although the replacements we were able to find didn't seem to be much better quality).
As krobbe mentioned, once the "throw" a few times, they wear out very fast.
We just replaced them all at the same time and no electrical problems since.

Posted By: OldSmokey on 07/07/17 10:42am

bren0035 wrote:

Ok, I'm new to this forum and usually don't need to ask for this type of help as I have a good group of people that have been trailering for many years and are good at answering my questions. I'm at a loss and wanted to see if anyone on here had some ideas. Here are the details for all you trailer Dr. out there.

I just bought a used 2007 KV Sportsmen (38 ft) travel trailer. We restored the interior of the trailer and before going out camping I checked everything I could, i.e., fridge, lights, water, toilet, sink, etc. We bought this trailer to use in Havasu/Parker Dam, CA. The temps in the summer are constantly in the 110-118 range so it gets hot and stays hot all summer.

I have two AC units on my trailer. The guy I bought it from installed the second (rear) AC on its own seperate breaker and upgraded the electrical to 50amps. THE PROBLEM I HAVE IS I CAN'T SEEM TO KEEP THE MAIN AC TO STAY ON!!! The back one will stay on all day and night and blows freezing cold air, but the main one has issues running during the day, BUT will stay on at night with little issues. It trips the breaker around 11-12pm during the day and will keep tripping every time I reset it. Once it gets to be around 8-9pm at night and the sun is down, I can flip it back on and it usually stays on all night or sometimes will trip once or twice, but then will stay on all night and blow cold air.

I thought it might be pulling too many amps because it was dirty so I got up on the roof the following trip and cleaned it real good. I also replaced the breaker. Still trips! I placed a fan on the internal breaker box thinking that maybe the breaker is getting over worked and hot, but it still trips. I'm thinking it has to do with heat as it trips right when it gets extremely hot, but why would it still trip if the AC inside was still cold? Will the AC trip if the external unit get too hot? Why does the back one stay on all day and have no issue?

I've also tried turning the back one off and letting the main one work and pull amps by itself, but the same thing happens. It's hard to trouble shoot because at one point the AC will work for many hours without problem.

I've had some people say to try putting that unit on a 25-30 amp breaker and put it on the bottom of the box so there's some space in the breaker box and allows for better ventilation. I'm fearful that I could allow the AC to fry itself, but believe the idea was that the AC was trying to run harder to keep up with the hotter temperature. Again, why would the back one have NO issue at all. They are both Coleman.

Sorry for the long post, but I need to figure this out or staying out there will continue to be a huge frustration for us. The back one can't keep the trailer cool during the late afternoon.

Thoughts.

first, make sure the coils are nice and clean.
if you still have issues then I would suggest replacing the compressor run capacitor, as they age the electrolyte inside dries out and the result is more amps drawn from the compressor and more heat, this will eventually trip the breaker.

if that doesn't fix it then the breaker might be tired.. LOL

Posted By: jyrostng on 07/07/17 11:00am

I see you have 50 amp service but how it it connected? always use the shortest and largest cord you can use and NO adapters.

Posted By: bren0035 on 07/08/17 10:21pm

Thanks everyone. I did clean out both units. I didn't use a hose but brushed and vacuumed both coils and they were very dirty. It still tripped. Should I try using water? Could I have missed enough dirt for it to still have trouble? The condenser coils didn't look too badly bent but I only saw one side as the other had the shroud and fan in front of it and couldn't imagine how that side could get messed up.

Posted By: bren0035 on 07/08/17 10:24pm

I'm on 30 amp service but the trailer is on 50 amps so I can't run everything at one time, but I still trip the breaker with just the one main a.c. on. Is the compressor run capacitor a part that is sold desperate from the compressor?

Posted By: time2roll on 07/08/17 11:03pm

I assume it is the 20 amp branch circuit that is tripping? Or is it the 30 amp pedestal?

Have you measured voltage in the RV?
The air that works draws power from the main 50 amp panel on its' own 20 amp breaker, correct?

Since you have replaced the 20 amp branch circuit breaker I have to start thinking the main air is drawing too much power (amps) due to low voltage or poor mechanical condition. You may need a new air conditioner. Best shot IMO is to call a mobile RV mechanic.

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Posted By: bren0035 on 07/09/17 12:19am

I did plug in a voltage meter and when the a.c. was running well the volltage was around 113-114...when mid day hit and weather was heasting up the voltage dropped to around 100 and that's when the a.c. souls start tripping. If get a new a.c. unit if I was sure that was the fix and not just an electric issue. Also, the main a.c. is on a tandem 20 amp breaker in the main 30amp fuse box. The back a.c. is on its own 20 amp breaker that is separate from everything else.

I'm new to this but does low voltage mean the a.c. will pull more amps?

Posted By: colliehauler on 07/09/17 03:33am

Yes the lower the voltage the more amps it will draw and will eventually burn up the compressor. There are automatic devices that will shut the power off when it drops below a certain point to prevent damage. There is a Hughs Autoformer that boost voltage to a safe level as well, if voltage drops to a certain level it will shut down as well. I think 100 volts is to low. Normal voltage is around 120 mine under heavy load drops to 117 volts. A brush and air will not get the stuff inbetween the coils. You have to take the covers off and clean with water, power disconnected and fan motor wrapped in plastic so it does not get wet. There is another good thread open on the same subject explaining in more detail. Dirty coils can cause the unit to draw more amps as well.

Forgot to add the fins need to be straighten (carefully) if bent to get good airflow.

* This post was edited 07/09/17 03:45am by colliehauler *

Posted By: stevemorris on 07/09/17 06:43am

100 volts is too low.
yes, electric motors draw more current at low voltages
check the electrical connections between the power supply and the ac unit, ALL of them but especially within the ac itself
cleaning the ac properly is important too
somewhere in the system you are loosing voltage under high current load. check the voltage at several places starting with the shore power cord. check the voltage at other outlets while the ac is running, if all the outlets are showing low voltage then the main supply is poor. if its just on the ac circuit at the ac, then its the ac supply
check the connections where the shore power cord joins the trailer wiring, the flex line to the pedestal will be joined to solid copper wire in a box somewhere, mines under the dinette behind the hole where the flex cord enters the trailer, probably a couple of big Marr connectors in there

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Posted By: jyrostng on 07/09/17 09:21am

bren0035 wrote:

Thanks everyone. I did clean out both units. I didn't use a hose but brushed and vacuumed both coils and they were very dirty. It still tripped. Should I try using water? Could I have missed enough dirt for it to still have trouble? The condenser coils didn't look too badly bent but I only saw one side as the other had the shroud and fan in front of it and couldn't imagine how that side could get messed up.

That's the side the air blows against, it's where the dirt builds up, it doesn't get damaged except from cleaning. Without looking at it, you'll never know what's in there.

when checking the voltage, you must do it when the compressor has a load on the 120v line. Where you are losing the voltage will be making heat, the extension cord, any adapters, any plugs, when the unit runs, the voltage drop is producing heat somewhere, look for that heat.

* This post was last edited 07/09/17 01:54pm by jyrostng *

Posted By: time2roll on 07/09/17 09:41am

100 is too low by any measure. Yes an inductive motor runs at constant power so as voltage drops the amps increase. Too many amps will also do long term damage to the motor from overheat. Be glad the breaker has been tripping. You need a voltage booster.

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Keep that air off until one of these has been connected.

Posted By: jyrostng on 07/09/17 01:51pm

You really need to find the voltage drop, it's a fire hazard. Find the voltage drop, you may fix your problem.

Posted By: bren0035 on 07/09/17 10:01pm

Ok, I will try this next time I go out.

Posted By: Wes Tausend on 07/11/17 04:45am

bren0035,

It seems to me that the guilty AC is more likely to severely drag line volts down and trip a breaker when it tries to start. This older unit may have taken more amps (especially starting) even when it was new, and now it has an old, dried out electrolytic start capacitor to boot. So the most likely unit to fail a smooth start SHOULD be the older one. Make sure it's not trying to immediately restart right after a shutdown when refrigerant pressure is not yet bled down.

You could check individual run amps when both are running and see if there is a difference. Individual start amps will be harder to catch than run amps.

If such checks reveal that the AC fails on start, you might consider installing an easy start capacitor on the compressor motor like some folks do when they have a smaller generator (like a Honda 2000) that can barely run AC, but not withstand the heavy start draw.

Here's a simple, short youtube install for example. Such caps are commonly available online just for RV's, just google "easy start capacitors".

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Why Is My RV air conditioner tripping the breaker?

Well, an air conditioner usually trips the breaker because it's pulling in more amps than the breaker is rated for. That is, if you have a 20-amp breaker and the AC pulls 30 amps, the breaker trips. That's why breakers trip: to protect you from over currents that can damage equipment and cause fires (yikes).

Why does my breaker trip when it's hot outside?

High Air Temperatures Ambient heat in the air surrounding the breaker can impact the components, too. When outdoor heat causes the strip to flex and hit a contact, the circuit breaker will trip even though there is no excess electricity causing the heat.