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Topic: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power (Read 583 times) previous topic - next topic
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Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
All,

Our air conditioner (and all rig AC power) shuts down after 2 minutes while operating on shore power. Then after 5 minutes, the AC power is restored and the air conditioner turns on, runs for 2 minutes or so and shuts down (with the AC power).  Five minutes later the power returns.  The air conditioner runs normally while on generator power. 

We’ve read on this forum that a possible remedy is tightening all connections and looking for loose wires on the power center.  Part of that info was turning off all power to the power center which entailed pulling the solar panel fuse followed by turning the battery disconnect switch off.  However the Solar Boost 3000i still shows voltage and amp readings.  Is there another step to be followed to insure all power is off? 

Also, an RV Tech suggested telephonically that it could be the transfer switch.  Any advice is very much appreciated.
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
 
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #1 –
Can anyone tell me where the transfer switch is on a 2015 MB?
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #2 –

Hi Don; Do you have a built in power monitor? It sound like you do, and usually it isn't connected to the generator.
(a known and controlled power source). Also called a surge protector, has about a two minute delay before it lets power through from your pedestal at a campground. It doesn't like high or low voltage.  It also checks for mis-wired outlets.
   The buss transfer relay is connected so that when your generator is producing power it shifts the coach incoming AC to the generator. It does have a delay of about 20-30 seconds to let the generator engine come up to speed and warm up (and settle down) before being 'hit' with the generator load. Tough on those internal combustion engines.
    If the AirCon works ok on the generator, then there is something it doesn't like about your shore power source.  My guess is that it is too little voltage. Below about 105 VAC. It isn't the buss transfer relay.
    I carry this with me and test pedestal sockets before I plug in.  Taiss GFCI Outlet Tester New Advanced Receptacle Tester with Voltage Display...   The readout will tell you about some problems.    RonB

As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #3 –
Quote from: DandTE  - 
Can anyone tell me where the transfer switch is on a 2015 MB?
The ATS is part of the fuse/converter assembly.  It’s on the backside of the panel when you open the access door.  If am not correct, someone should shortly correct me for which I always appreciate.
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #4 –
Thanks for your advice. 

For more context:

- we have a Progress Industries portable EMS at the post. With the rig not connected to shore power, it reads 123v, 60hz, no error codes. With the rig on shore power, air conditioning and other electrical draws on, it reads 119v, 18A, 60 hz and no error codes. After 2 min, the AC power to the rig shuts off, and the EMS reads the original numbers and power is still applied the the 30 amp rig plug. After 5 mins, AC power turns back on in the rig.

-  we checked the wire connections on AC and DC  sides of the power center. All good.

- no problem running the air conditioning on generator

- a local RV tech took a look and was stumped by the LD electrical layout. So, the issue persists.

Thanks again for your suggestions and advice.

Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #5 –
Try running the A/C on shore power with the EMS disconnected. Using a plug-in EMS, the generator does not run through the EMS.
Good chance the EMS is bad or the power pedestal is not wired correctly.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #6 –
Tried Larry’s suggestion of by passing the portable EMS and plugging in directly to the post (30A). Air conditioner ran for almost 10 minutes, then the AC power cut off. The breaker at the post did not trip.  Tried it again on the 50A plug on the post (no EMS). Air conditioner ran for less than 2 minutes and the AC power cut out.

So, the AC power only cuts out when the air conditioning is on. 

Random thought:  House batteries are getting weak through age. Not sure if this has a bearing.
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #7 –
The A/C compressor has an attached thermo-overload switch that can cause this problem if the thermo switch cuts the power off when the compressor has not overheated.
Our LD's A/C had this problem when the A/C was new, it took repeated trips to a Dometic repair shop to demonstrate the issue and to get it replaced. I was not able to buy the switch, Dometic did not have them available to the public, only authorized repair shops could supply them. Things may be different now.

With the A/C's rooftop cover removed, the switch can be tested with a multimeter during the time the A/C has shut down. This is best done by a trained tech to eliminate the chance of being shocked, electrocuted, or causing damage.

Larry

 
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #8 –
Thanks, Larry.  Unless another suggestion comes along, I guess we will selectively cool the coach using the generator as allowed at the campground. We are in southeast Mississippi at the SELD Spring Get Together.  Temps in the mid-80s.  We will get it to a Dometic authorized repair shop soon.
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #9 –
Hey Don,
Everett also suggests the capacitor in the AC unit has gone bad. It is easily replaced. They will act similar to your symptoms. Generic capacitor is about $15 on Amazon, Dometic capacitor is in the $60 range, same capacitor just not branded for Dometic.  Try to not use AC if you don't have to it can cause more issues.  Also check any wiring for mouse damage.

Sand Castle (Theresa & Everett) Surfside
01'  26.5 Mid Bath,   2018 31IB
Michigan born and starting to explore the US with my  spouse and our furry friend. Enjoying joining LD group rallies.
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #10 –
Quote from: Ed & Margee  - 
The ATS is part of the fuse/converter assembly.  It’s on the backside of the panel when you open the access door.  If am not correct, someone should shortly correct me for which I always appreciate.

Does anyone have a picture or schematic of this area for clarity?

We continued trouble shooting and found that the AC power (shore power) also shuts off when the heat pump runs and when the microwave runs with an electric space heater on low (23A total).  So, it seems the problem is in the ATS area.  Again, everything runs fine on generator.

Thanks.
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #11 –
Hi Don, if the AC breaker, Main 30Amp, trips in the coach consistently, then there might be a problem with that breaker.  I believe that in your year the factory included an incoming power monitor.  So that could also be contributing to the problem.  Surge current starting up the roof heat pump, may be exceeding limits of the main breaker. That's why 'soft start up' circuits are so useful.
   This thread started by Greg (HiLola) should help:  AC Not Working  and reply #47 and #49 resolve the problem.
    That it runs fine on generator, I can only think that maybe the generator AC current or voltage is a little different?      RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #12 –
Thanks Ron.  To be clear, no breakers are tripping.  The house (shore) power cuts off then returns with, no intervention by us, in 2-5 min.

Quote

On Apr 23, 2024, at 1:11 PM, RonB
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #13 –
Quote from: DandTE  - 

We continued troubleshooting and found that the AC power (shore power) also shuts off when the heat pump runs and when the microwave runs with an electric space heater on low (23A total).

To be clear, no breakers are tripping.  The house (shore) power cuts off then returns with, no intervention by us, in 2-5 min.

A 23-amp draw when running the heat pump, space heater, and microwave at the same time seems low, it should be in the 30-amp+ range. I do not know how much power the A/C uses in heat pump mode but would assume it is the same or similar as when cooling mode.
In most LDs, running the A/C, microwave and space heater at the same time would trip the power Center's main breaker.

Does your LD have an EMS device? If so, I would suspect it is the problem, especially after hearing there is a 2-5 minute delay in re-establishing the power.

Larry.

Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #14 –
Thanks, Larry.  The 23 amp load was for the microwave and space heater.  The heat pump draw is similar to the air conditioner - 18-19 Amps (includes fridge and other minor draws in the coach).  These loads were observed on the portable EMS.

Based on your recommendation last week, we ran the coach with and without the EMS on both the post’s 30 and 50 amp outlets.  We have also used two different smart plug cables and three different AC shore power sources.  All combinations yield the same result when a “large” load (18-23Amps) is applied through different appliances.  On generator, all loads appear to handle normally.
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #15 –
Quote from: DandTE  - 
Does anyone have a picture or schematic of this area for clarity?

We continued trouble shooting and found that the AC power (shore power) also shuts off when the heat pump runs and when the microwave runs with an electric space heater on low (23A total).  So, it seems the problem is in the ATS area.  Again, everything runs fine on generator.

Thanks.
JOR posted a couple of photos of his transfer switch on the back of his converter.

Kendall
Kendall & Donna
2019 TK  "RIMRIDER"
2023 Jeep Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #16 –
Hey, this is very helpful.  Thanks.
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #17 –
May have diagnosed the problem…

So, we got into an RV dealership and, working alongside the tech measuring voltages, when the power cut off there was no voltage coming into the ATS.  But there was voltage at the head (female connection) of the smart plug power cable.  Taking the male smart plug receptacle off the RV exterior wall and measuring voltage at the back of the receptacle where the hardwire to the ATS begins, we found no voltage.  So, we called Smart Plug support and found out that our plug (8 yrs old) was one of the earlier designs that had a thermo-coupler in it.  So, it appears that it was cutting out with the heating of “heavier” power loads and cooling down in 2-5 min to restore power.  The support guy said they have experienced this symptom with the early designs.  They have since taken that coupler out of the design.  The part to replace the backend of the male receptacle is coming from Amazon on Monday. So, we will see if this is the fix.

Thanks to all for your advice and suggestions.
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #18 –
That is a cause I would assume none of us knew about or guessed it would have, but now we do.

A thermal cutout seems like a strange device to include in a power plug when there are already breakers in both the Power Center and the power pedestal.
For being a "Smart Plug", without a light or other fault indicator, it seems like a dumb addition.

Loving our 22-year-old Marinco marine plug, I never had an issue with it.
Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #19 –
I agree with Larry! Many plug in cables have a light at the end connector to signify power being present. To put in a thermal fuse, they could as easily have added a green/red LED to signify that power was interrupted intentionally, and that it was designed to do that. My 'dogbones' have that feature.  Think of the money and aggravation that would have saved!   RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #20 –
It seems that the inventor of the Smart Plug was a boater who was very concerned about electrical fire and added that as an extra “safety” feature.  Ironically, the boating community’s equivalent to the RVIA would not endorse it because of Larry’s logic.  So, Smart Plug removed the coupler for the boating endorsement and market share.  Turns out that the design removed the coupler in 2017.  So, if anyone has a Smart Plug that pre-dates 2017, file this experience away for possible future use.

We ended up going to the Smart Plug in 2016 because our Marinco overheated and had a melt down.
Don & Tery
2022 MB 27.5 towing a 2017 Wrangler
Re: Air Conditioner Cutting Shutting Down After 2 Minutes on Shore Power
Reply #21 –
This is secondhand, so take it for what it's worth, but...

A very knowledgeable boater friend told me that Hubbell-type (e.g., Marinco) shore power connections are a common cause of boat fires. In a damp and sometimes salty environment, they can corrode and overheat, and your very expensive boat burns to the waterline at the dock, often taking other boats with it. It wasn't just boats that experienced this--viz. DANDTE's meltdown experience.

The SmartPlug system was designed from the ground up to avoid this risk. The heavy-duty electrical contacts and sealed physical connection were one way to accomplish this, and the thermal cutout (not "coupler") included in the original design was another way of preventing overheating. I agree with Ron that they should have included an indicator to show when the thermal cutout had activated, rather than leaving users to guess. But the idea was sound.

"A thermal cutout seems like a strange device to include in a power plug when there are already breakers in both the Power Center and the power pedestal."

But a fuse or circuit breaker doesn't protect against overheating. It only responds to overloads and short circuits. The breakers mentioned can't prevent a fire at the shore power inlet. The thermal cutout in the original SmartPlug could. Again, the idea was sound.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"