No A/C on 50 amp service

[BlackKnight]

I am trying to figure out why I can not get roof A/C to work on 50amp post power but both A/c units work on generator power. Never had a problem before and both A/C's worked fine till this point. I checked breakers in bedroom and fuses and found nothing. 2007 Monaco coach. Anyone had a similar situation? I can run the microwave and other 110 and 12v outlets. Thanks Steve

[wolfe10]

Steve,


From the ATS (automatic transfer switch) onward through wiring and main 120 VAC breaker box shore power and generator are EXACTLY the same.


So the issue is either with the shore power itself, any protection device you have on on the "shore power IN" side of the ATS.


I would start by verifying with a voltmeter that the shore power outlet is good. If you need the "how to check" let us know.


Next and also easy is, with all power off to check connections in your ATS.

[Skip426]

OK have you confirmed 120 volts at each hot leg at the post ?

Your microwave maybe operating off your inverter and the post power is dead or circuit breaker tripped there .
Have you asked your neighbors about power supply ?

EDIT: I see Brett , posted while I was typing , sorry about the duplication , but your description points to shore power not getting into coach systems .

[jacwjames]

X3 on checking transfer switch.

[BlackKnight]

so, I failed to mention I have used this post at my home for 2+years-never a problem-I have always used a Hughes 50amp surge protector. While electronics is like eating for others, I would starve to death. If you would help me, tell me what I need to check to go forward. I did purchase a new transfer switch almost a year ago but have not installed-I did check to make sure the exsiting transfer switch lugs were tight and no signs of heat or burning. Thanks

[TXiceman]

Check the transfer switch, but first you have to find it. Tap it with a plastic handle and see if it will release.

Ken

[twinboat]

Can you do a test without the surge guard device.
Do you have a cord reel ? It may be bad.

[Skip426]

You checked the connections in the transfer switch for tightness , so you know exactly where they are .

Do you have a multi meter to check for 120/240 volt in and out of the switch or a non contact 120 volt power tester .

Can you post a picture of your transfer switch ( cover off ) and we'll be able to tell you exactly where to check with the meter to confirm power flow through it .

[wolfe10]

Suggest you spend 30 seconds checking your shore power outlet with your voltmeter. Would hate to see you tear into your coach only to find out it is a shore power issue:


Two outer straights are the HOTS (L1 and L2)
The center straight is the NEUTRAL
The center round is the GROUND


So:


From either outer straight to either center= 120 VAC
Center straight to center round= 0 VAC
Outer straight to outer straight= 240 VAC


If those check out, do the same test at the "shore power IN" side of the ATS and then at the OUT side of the ATS


Generally colors are as follows, though they could be different:
Black is HOT
Red is the other HOT
White is NEUTRAL
Green is GROUND


So either black or red to green or white= 120 VAC
Green to white= 0 VAC
Black to red= 240 VAC

[Skip426]

Here's a diagram to go with Brett's description.

[BlackKnight]

Brett- I checked power at the post as you mentioned and all is fine 120 and 240. plugged in the surge protector(hughes 50amp) and checked across the ATS red and black 240v and 120 on l1 and l2. Unplugged the surge protector and hooked coach direct to the pole-no change. Went to the breaker panel in the rear bathroom, shut off all breakers and reset-no change. Switched mode on controller to fan only high manuel-no go. All works fine on generator power. What next?

[YC1]

Do you have a panel (EMS), that shows for example 50 amp or 30 amps when adapted down for a 30 amp service?

It is possible your EMS load shedding device is confused. Of course I do not know your setup so providing that information will help.

IF you have this there is a circuit board behind the AC breaker panel. Lots of things in there to hurt you so no jewelry and one hand in your lap while taking measurements.

The circuit board passes power through relays and when on 30 amp service they will unload devices to help prevent overloading the 30 amp service.

If the device is confused for some reason it might be unloading devices and your AC's could be at the top of the list to unload.

Here is a bunch of files with pictures that might help you sort it out. Look at the pictures of the AC breaker panel and let us know if you have something like it.

https://1drv.ms/u/s!Aqrv2TUdbV6xjl_O...H0evI?e=ijJU07

[2cyber71]

Do yourself a favor
1. Unplug
2. Turn off your Chassis, and house switches and inverter
3. Wait 30 minutes.
4. Turn on all your switches
5. Plug in
See it fixes everything

Believe me, this simple move can do wonders

[windsorbill]

My 06 came with an Intelliec EMS. The main board is within the circuit breaker panel. It has 'intellitec' printed on the cover.

Not sure what an 07 Knight came with. Post a picture of your circuit breaker cover. There is a 'reboot' procedure, if they are similar.