Help with Electrical Problem please

[Mark Lane]

Hi All:

I have a 50 amp Motorhome with a hardwired Progressive EMS system. When I plugged into the electrical pedestal at the park yesterday, only one A/C would run.

I checked the Progressive display and it is reading for both Line 1 and 2 that it is drawing close to 120 volts, but the amp reading is very low. 4 amps on one line and 0-2 on the other line. Shouldn't it be reading much higher?

Do you know what would be the cause of such a low amp reading?

When I disconnect from the power pedestal and run my onboard generator, both air conditioners run fine.

I confess that I don't understand all I need to know about the electrical system and your help is very much appreciated!

Mark

[xrated]

Originally Posted by Mark Lane

Hi All:

I have a 50 amp Motorhome with a hardwired Progressive EMS system. When I plugged into the electrical pedestal at the park yesterday, only one A/C would run.

I checked the Progressive display and it is reading for both Line 1 and 2 that it is drawing close to 120 volts, but the amp reading is very low. 4 amps on one line and 0-2 on the other line. Shouldn't it be reading much higher?

Do you know what would be the cause of such a low amp reading?

When I disconnect from the power pedestal and run my onboard generator, both air conditioners run fine.

I confess that I don't understand all I need to know about the electrical system and your help is very much appreciated!

Mark

If everything runs fine with the genny, that may be an issue with your automatic transfer switch. I would check it out as a first place to look.

[wolfe10]

Originally Posted by Mark Lane

Hi All:

I have a 50 amp Motorhome with a hardwired Progressive EMS system. When I plugged into the electrical pedestal at the park yesterday, only one A/C would run.

I checked the Progressive display and it is reading for both Line 1 and 2 that it is drawing close to 120 volts, but the amp reading is very low. 4 amps on one line and 0-2 on the other line. Shouldn't it be reading much higher?

The voltage of 120 VAC is perfect.



The amp reading depends totally on what you are running in your RV. If nothing is on, zero amps are being used. If both A/C's are running both L1 and L2 will show higher readings since you are using more power.

What was on in your RV when you got the "very low" amp rating?


What did not run on shore power?

[bigchick]

i'm assuming the ems is wired into the shore power line before the transfer switch.

if everything works from the generator then you problem is between the ems output and the shore power input of the transfer switch.

the ems displays the voltage from its input side and the amperage that is flowing through it. since it shows voltage on both legs it is getting input power.

you problem is most likely a loose connection. it it could be that the ems is not passing both legs of its input power or the transfer switch in not passing both legs of shore power input to its outputs. or perhaps a disconnection in a junction box between the two. it should be quite easy to find by tracing voltage with a multimeter. and the correction is probably to reattach the loose cable and tighten the connection.

but you say you are not real familiar with electrical work. do not work on it while it is live unless you are confident with what you are doing. you would be working around live 120 volt circuits!!!

one thing you could do, again if you feel confident, is to completely unplug from shore power. then you could open the case of the ems and the transfer switch to visually look for a loose connection. you might find it and be able to fix it. if you don't feel capable your best bet might be to call a mobile rv mechanic.

you problem is is a very constrained location which should be very easy to find. it is resolvable!

[Mark Lane]

Thank you very much for your suggestions and guidance!

[Tha_Rooster]

Originally Posted by Mark Lane

Hi All:

I have a 50 amp Motorhome with a hardwired Progressive EMS system. When I plugged into the electrical pedestal at the park yesterday, only one A/C would run.

I checked the Progressive display and it is reading for both Line 1 and 2 that it is drawing close to 120 volts, but the amp reading is very low. 4 amps on one line and 0-2 on the other line. Shouldn't it be reading much higher?

Do you know what would be the cause of such a low amp reading?

When I disconnect from the power pedestal and run my onboard generator, both air conditioners run fine.

I confess that I don't understand all I need to know about the electrical system and your help is very much appreciated!

Mark

No way you could have airs running at 4 amps.
Are you sure you have power on L1 and L2?
Have you turned pedestal breaker on and off?

[Archer2]

Suspect problem in the shore power pedestal, the shore power plug, the Progressive decide or its wiring, the shore power cord reel connectors, the Automatic Transfer Switch or its wiring.
Are you reading the voltages/currents on the display on the Progressive power monitor or are you reading from the display inside the coach?
It sounds like you are dropping one of the 2 legs of shore power.

[Mark Lane]

Well, new wrinkle.

I didn't find any loose connections and both air conditioners worked fine on shore power until 1 pm today when the back a/c started clicking again trying to start the compressor.

Thinking it was some low voltage in the park during the heat of the day, I unhooked power at the pedestal and turned on the generator. But now that same air conditioner in the back still won't start the compressor. It tries, but shuts off immediately. It tries again at short intervals.

Does it sound like now, it was really an air conditioning problem all along?

Should I consider changing the control panel in the air conditioner?

Thanks for your guidance.

[chuckftboy]

Might be as simple as a bad run capacitor or start capacitor on the a/c that is dropping out. If you have a bad run capacitor the compressor will draw high amps and eventually go out on its thermal overload.

[2004Horizon]

Everything above is possible.

Off hand, did you open your ATS can torque down your lugs?

Mark Lane:

What is your RV year and model?

Do you have a basement AC or rooftop?

Any idea on what type of ATS you have?

What generator are you running?

Note: If you have pre-2010 RV with an Onan QD7500/QD8000, then all these questions need to be answered.

[Mark Lane]

Thanks to all who helped with this issue. I have a RV Tech coming out this afternoon to look into all that you have suggested. I will give you an update when it is solved.

Many thanks for taking the time to help!

[TimmyB]

Originally Posted by Mark Lane

Thanks to all who helped with this issue. I have a RV Tech coming out this afternoon to look into all that you have suggested. I will give you an update when it is solved.

Many thanks for taking the time to help!

We had a similar problem at our "home" park in FL, where we stay for 7 months. Right after we arrived, we noticed one of the AC's kept turning off, especially when we would fire up the other one or the microwave or the dryer, etc. Both sides of the pedestal read correctly at around 120V. What we DIDN'T know was to check them together. Should have read 240V; it read .3V!!! They simply split one 120 line and ran it to BOTH sides, giving the impression that it was a 50A site. Our Hughes PWD50 was tricked into thinking everything was OK, but only at 30A. Make sure your pedestal is wired truly at 240. Might save you a lot of work.

[Mark Lane]

Hi All:

Thanks again for all your suggestions. Here's where I am.

The park checked out the electrical pedestal and said it was good.
The RV Tech did the following:
Checked all the capacitors (start, run, and thermal) and they all showed they were good.
Compressor tested as good.
Cleaned the coils thoroughly with a no rinse coil cleaner.
Opened the Progressive EMS and tightened all the lugs. (a couple would turn an 1/8 of a turn)
Opened the Automatic Transfer Switch and tightened all the lugs (again a couple of them would turn a slight amount).

It has not acted up again until today. The pattern is early to mid afternoon in the heat (Texas). It has a couple of false starts where it tries to click on, but fails. It repeats the process every minute or two and then the compressor starts and everything is fine.

Could the start capacitor test okay, but be slowly failing?

Thanks again for your input!

[wolfe10]

What is the AC voltage when this happens?