Can you help with this electrical problem

[Sundog]

I am out in our 2004 Dutch Star. We seem to be having a power or regfrig problem. Symptoms are the A/c seems to be having a real problem keeping the coach cool. Only running 1 unit as both won't run at the same time so front and rear units cycles back and forth. Yes, we are on 50 amp service. Frig is warm. Frezzer is fine but frig is barely at 45 degrees. I have started the generator and disconnected the elctric cord to see if Gen can allow for better cooling and lower frig temps. A/C seems to be working better all ready. Temps in low 90s no direct sunlight on coach.

Thanx,

Sundog

[Sundog]

I am out in our 2004 Dutch Star. We seem to be having a power or regfrig problem. Symptoms are the A/c seems to be having a real problem keeping the coach cool. Only running 1 unit as both won't run at the same time so front and rear units cycles back and forth. Yes, we are on 50 amp service. Frig is warm. Frezzer is fine but frig is barely at 45 degrees. I have started the generator and disconnected the elctric cord to see if Gen can allow for better cooling and lower frig temps. A/C seems to be working better all ready. Temps in low 90s no direct sunlight on coach.

Thanx,

Sundog

[Hitchhiker]

Is the voltage low on the 50 amp service?

[Sundog]

No, voltage at the box is 110 plus on two legs and inside when testing outlets it is 110 plus (actual 118)

[Route 66]

As Richard posted, the first step to check the voltage at the pedestal.

If you don't have a volt meter, the campground can check it.

Verify that you have 120 volts on each leg.

103 is the minimum voltage that is acceptable.

EMS units will cut off at this voltage to prevent low voltage damage to your rig/appliances.

[Route 66]

118 is fine.

How low does it go with the AC and fridge running.

[GaryKD]

Hi Sundog,
It is important to know.
1. The voltage on both legs of the 50 AMP service with a light or no load.
2. The voltage on both legs of the 50 AMP service with both A/Cs and anything else you have running.

Can you provide this info?

[Sundog]

I'm not an EE but I just checked the interior outlets and they are showing 115+ volts. I don't know how to check the volts from the pedistal without unplugging the coach. But when un pluggeged the 50 amp service shows 118+ on both legs and the 30 amp service shows 118+ volts. Does this help?

[RVDude]

Help me understand why both HVAC units will NOT run simultaneously? They should. And, what exactly happens when they "cycle back and forth"? What is the HVAC input and output air temps after it has been running for 15 mins or so?

The refer will take many many hours to get cold. So, your refer genset test may not provide any meaningful info. If it is a LP refer, switch it to LP and see what happens - overnight.

Low voltage is not really going to cause noticeable low cooling in the AC units, it'll just cause them to overheat and burn out. UNLESS the voltage is so low that the compressor fails to start - that probably is sub 100v under load. So I think I/we are not understanding what you are saying and there is somethig else going on.

Low voltage to the refer may cause poor cooling due to the lower heat applied to the absorption unit. But again, the refer will take overnight to settle to a set temp.

[Bruce W]

This might be related to another question I saw. It was talking about using one of the adapters that plug into 2 30amp receptacles and has a single 50 socket on other end. As I understand it a 50amp circuit normally has to 110v legs 180 degrees out of phase. On the adapter it is possible to plug into to 2 30amp sockets each on the same phase. The symptoms they were getting with the 2 legs of the 110volts on the same phase sounds similar to yours

[Bruce W]

Check the phases by measuring voltage between the 2 legs, 220v=out of phase/ 0v=inphase where you are plugged in. 2 in phase legs could overload the current on the neutral leg possibly IMHO resulting in your symptoms .

[Sundog]

Here is a current summary of what in the heck is going on..........The refer has been running since last Thursday and was fine when we left home. It does switch to LP while on the road and no problems. The only time we thought we had a prblem was after we parked here in Chatanooga. The A/C cycling back and forth is best descibed as both units running but only one with its compressor running and actually coolong while the other is just running its fan for air circulation. I ran gen instead of 50 amp service and did see a difference after about an hour. Then I switched to the 30 amp service (not using the 50 amps) and ran only the front A/C. This front unit seems to run fine and keeps us very comfortable (wouldn't do that before on 50 amp with both units running). Also the refer seems noticably colder this morning. I can't imagine why there would be such a difference between 50 amp service and 30 amp service. I would expect it would produce the opposite results. Any thoughts? Am I giving you a clear picture of what is going on? Sorry for the "non technical" descriptions.

[hondo122]

Can you change sites? Maybe a pedestal problem.

[Spikester]

Sounds like you have narrowed your problem down to the 50 Amp feed off of you pedestal or a defective leg connection on your 50 Amp power cord.

By running your generator with satisfactory results you have eliminated the generator side of your transfer switch and all things downstream.

By switching to the 30 Amp feed from the pedestal with satisfactory results you have eliminated 2 legs and the ground/common on the pedestal and your power cord.

The only thing that remains is the third leg on the pedestal, power cord, or its connection to and your transfer switch. This is also indicated by the operation of your AC units when plugged in to 50 Amps from the pedestal. If you had a bad supply leg one would operate satisfactory the other may operate erratically as they are not wired to the same legs.

As suggested switching pedestals will isolate your problem further, if problem goes away its the pedestal, if not your cord or the cord side of your transfer switch. I suspect the pedestal especially because this is the first time this has manifested itself, but could be a loose connection on the incoming side of your transfer switch.

You done great with your troubleshooting so far. Good luck in your quest!

Spike