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Topic: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS (Read 503 times) previous topic - next topic
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AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
We haven't used our 2002 MB for several months.  I started it this morning and checked out various systems running under DC power.  When I plugged in to AC I have not AC service in the motor home.  Is there a relay somewhere that allows ac to operate?  I couldn't start the generator as the batteries are weak so I thought I'd plug in and charge the batteries, but no AC.  Any ideas of what I could check?

Thanks.  B. Nunes
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #1 –
Check the breaker for the AC.   This happened when I plugged in at my aunt's house a couple of years ago--I had juice to the rig & the microwave/hairdryer/etc. worked, but no AC.  Finally one of by brain cells kicked in & I thought "What would I do in the S & B house?  I'd check the breaker panel."  I did & that fixed it.  Good luck.

Lynne
Lynne
LDy Lulubelle, Green '05 31' TB
Lilly, the 4-Legged Alarm
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #2 –
Quote from: bnunes2002  - 
We haven't used or 2002 MB for several months.  I started it this morning and checked out various systems running under DC power.  When I plugged in to AC I have not AC service in the motor home.  Is there a relay somewhere that allows ac to operate?  I couldn't start the generator as the batteries are weak so I thought I'd plug in and charge the batteries, but no AC.  Any ideas of what I could check?

Thanks.  B. Nunes
Lynne is right to check the breaker in the LD. But how about the breaker at the source of your AC power? In a house, garage, etc? Check the breakers there.
Chris
Formerly: 2002 30' IB
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #3 –
Yes, I have checked all the breakers, thank you and there is power at the source plug.
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #4 –
Another possibility is a failed automatic transfer switch (ATS). That switch--actually a relay--is mounted on the back of your Parallax power center (the brown box below the sink). It's supposed to automatically route shore power or generator power to your AC outlets, but it can fail in one position or the other.

Here's something to try. Even though your batteries are weak, you may be able to start the generator when the Ford engine is running, as the alternator supplies a lot of power. If you can get the generator running, and if you then see 120 VAC at your outlets, then I'd suspect a bad ATS--stuck in the generator position and thus not allowing shore power to get through.
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #5 –
Does your rig have a hardwired surge protector?  If so, you could have power at the source plug but nothing in the rig.

As Andy said, it sounds like a bad ATS is the likely culprit.  While they usually fail in either Generator mode or Shore mode, I did have one that failed both ways.  If you can get the generator going and have power, but none with the shore power, it is almost certain to be the ATS.

Are your electrical skills up to working on the electronics?  If so, here are step-by-step instructions to check and to replace the ATS.  IF YOU ARE UNCERTAIN OF YOUR ABILITIES IN THIS AREA, DO NOT TRY THIS!

1) Cut the power.  Check with a meter to be certain there is no 120v power in the system.

2) Remove the brown power panel cover using a Torx head driver.

3) There are 4 hex head screws going into wood in the top left and right, and the middle left and right of the power panel frame.  Remove them.

4) Slide the power panel toward you until it clears the frame and you can tilt it forward to see the ATS mounted on the back.

5) Open the top of the ATS.  This is usually done by loosening or removing 1 to 3 screws on the ATS cover.

6) Looking down into the ATS, you will see 3 bare grounds connected to lugs on the side, and you will see three white and three black wires connected to six lugs.  I will call them 1 through 6, left to right.  One, two and three are black and four, five and six are white.  THIS IS POTENTIALLY DANGEROUS!  Turn the power on and use your meter to check voltage on the wires.  Check between #1 and #6, between #2 and #5, and between #3 and #4.  On my rig 1 and 6 are the power from the ATS to the power panel, 2 and 5 are the generator and 3 and 4 are for the shore connection. If yours is wired differently, make a note of how your wires connect, so you get it right at re-assembly.  With your rig connected to shore power, you should find 120v on the Shore connection pair, 3 and 4.  Once you find power there, check 1 and 6.  If there is no power there, the ATS is bad.  If you have power at 1 and 6, the ATS is working, and your problem is probably inside the power panel.  You need a pro.  If you have no power coming in from the Shore Connection,  your problems lie elsewhere, probably in your shore connection cable or its plug, its socket, or the plug on the wall of the RV.

7) Turn the power off.  MAKE SURE IT IS OFF!

8) I have worked on 4 ATS's, and all 4 attached differently to the power panel.  In one case I had to remove the breakers, drill out rivets, and drill new holes for the self tapping screws mounting the new ATS.  I found a Parallax link at http://d163axztg8am2h.cloudfront.net/static/doc/f6/f3/baa96cf1c020f6f561dfa1303f92.pdf that may be helpful.

The basics are, loosen the 3 white, 3 black and 3 ground wire lugs.  Loosen the strain reliefs.  Remove wires, then remove the old ATS from the power panel.  Attach the new ATS to the Power Panel.  Re-mount the wiring, doing the grounds first, then 1 and 6 for the power panel, 2 and 5 for the generator, and 3 and 4 for the shore supply.  Follow the torque settings for the lugs.  That is important.

Gee - I sure made that sound simple.  When I did it, it has NEVER been simple.  If it sounds confusing, challenging or intimidating, do not even try.  Get a pro to do it for you.  If you screw it up, you can fry your panel, fry your shore cable, burn up your rig, or fry yourself.  I say again, if this is outside your skill set, get a pro to do it.

OK, put the cover on the ATS, slide the panel back into position, put in the 4 screws and re-mount the brown cover.  You're done.

Ken F in NM

'08 MB
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #6 –
Thanks, Ken; very useful information! I get it; I won't touch the ATS, but I get it!  ;)

And, I definitely second the warnings to assess one's skill set very carefully before attempting a job that could fry the rig or send a jolt through one's person! Some fixes on the rig are in the "Here, hold my beer...." category, and some are not; jobs involving stuff that sparks, smokes, and/or blows up are best left to the pros! Knowing (and accepting) one's limitations can be a lifesaver!  :D

2003 TK has a new home
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #7 –
I think Clint Eastwood said it best . . .

https://www.youtube.com/watch?v=_VrFV5r8cs0
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #8 –
If Ken's explanation is not in the Companion, would someone please add it?  Excellent explanation, and thanks, Ken.  Having survived near electrocution while repairing a dryer, I'm fearless!  (Just kidding-- about the latter)
-- Jon, happy I inclined the rig for runoff during our SoCal rains
(Former) ‘06 TK “Albatross.” And (former) Vespa 250.   Alas, no more; both are gone.😕 Great memories remain! 😄
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #9 –
Quote from: Jon & Loni  - 
If Ken's explanation is not in the Companion, would someone please add it?  Excellent explanation, and thanks, Ken.  Having survived near electrocution while repairing a dryer, I'm fearless!  (Just kidding-- about the latter)
-- Jon, happy I inclined the rig for runoff during our SoCal rains
Jon, I have asked Don if he would add this to The Companion.
Chris
Formerly: 2002 30' IB
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #10 –
Kenneth Fears has graciously provided me with technical support for checking the wiring in the ATS, something that I wouldn't have ever thought about on my own.  You might remembered that Kenneth made this suggestion in one of his posts within the last week or so.  At any rate, Kenneth mentioned that loose wiring in the ATS will cause problems with the switch and can cause it to melt or worse.

I found a YouTube video (45 seconds) that shows a melted ATS and the narrator believed the cause was loose wiring.  Next on our agenda ... we're going to check the ATS wiring in our LD before we drive one (1) more foot! 

https://www.youtube.com/watch?v=hnj9HEgmqQ0

Hope this helps.
 
Re: AC Not working on 2002 Mid Bath/How to Replace an Automatic Transfer Switch (ATS
Reply #11 –
So today we dug into the control panel with the breakers and automatic transfer switch (ATS) according to Mr. Ken Fears' guidance.  All the screws in the ATS were tight as were the various wires in the breaker panel and in the 12V fuse panel.  The nut holding the 12V ground wire was not tight ... now corrected.  In addition, the single sheet metal screw holding the ATS cover was stripped and that is also corrected.   At the end of the day, we have some peace of mind about the ATS wiring and we were able to corrected a couple of items.  A good day for the home on wheels.