GMCforum
For enthusiast of the Classic GMC Motorhome built from 1973 to 1978. A web-based mirror of the GMCnet mailing list.

Home » Public Forums » GMCnet » No AC for my A/C! (Rooftop air has no 110VAC)
No AC for my A/C! [message #347177] Sun, 01 September 2019 19:46 Go to next message
ljdavick is currently offline  ljdavick   United States
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
Senior Member
I'm an unhappy, sweaty, middle-aged, suburbanite who can not seem to figure out why I have no power to the roof Air Conditioner. I have one roof air - in front - and it's a newer Atwood uint. Checking for power at the unit I found it was dead. I checked the overhead plug in the rear hallway ceiling - power. Still I checked the breakers. They operate as expected and current is running when on, not when off. So that's good.

My beloved PO had installed an automatic switch that draws power from the cord or Onan as available, but it looks like there's more to it than just that. I shoved my phone in to take some pictures that I'll post to the photo site that show a blue box called Gen-Switch and another blue box called PowerGuard both from Trans-Tech of Plano Texas. I suspect the issues I had with my old air conditioner may have been related to what I'm experiencing now.

A cursory web search brought up little for Trans-Tech of Plano, so I'm hoping someone here might have a memory of what this kind of thing is. Without air conditioning we are not happy campers.

Alternately what would you replace this with? Is there current tech that might be compelling enough to rip it out and upgrade?


Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
Re: No AC for my A/C! [message #347179 is a reply to message #347177] Sun, 01 September 2019 19:56 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
Senior Member
ljdavick wrote on Sun, 01 September 2019 20:46
I'm an unhappy, sweaty, middle-aged, suburbanite who can not seem to figure out why I have no power to the roof Air Conditioner. I have one roof air - in front - and it's a newer Atwood uint. Checking for power at the unit I found it was dead. I checked the overhead plug in the rear hallway ceiling - power. Still I checked the breakers. They operate as expected and current is running when on, not when off. So that's good.

My beloved PO had installed an automatic switch that draws power from the cord or Onan as available, but it looks like there's more to it than just that. I shoved my phone in to take some pictures that I'll post to the photo site that show a blue box called Gen-Switch and another blue box called PowerGuard both from Trans-Tech of Plano Texas. I suspect the issues I had with my old air conditioner may have been related to what I'm experiencing now.

A cursory web search brought up little for Trans-Tech of Plano, so I'm hoping someone here might have a memory of what this kind of thing is. Without air conditioning we are not happy campers.

Alternately what would you replace this with? Is there current tech that might be compelling enough to rip it out and upgrade?
Larry,

Is there any reason that you can't rip that thing out of there to get the A/C working and worry about the fine points later?

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: [GMCnet] No AC for my A/C! [message #347180 is a reply to message #347177] Sun, 01 September 2019 20:09 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
Senior Member
Larry, 0is your coach a Coachman, Royal ?


On Sun, Sep 1, 2019 at 5:47 PM Larry Davick via Gmclist <
gmclist@list.gmcnet.org> wrote:

> I'm an unhappy, sweaty, middle-aged, suburbanite who can not seem to
> figure out why I have no power to the roof Air Conditioner. I have one
> roof air
> - in front - and it's a newer Atwood uint. Checking for power at the unit
> I found it was dead. I checked the overhead plug in the rear hallway
> ceiling - power. Still I checked the breakers. They operate as expected
> and current is running when on, not when off. So that's good.
>
> My beloved PO had installed an automatic switch that draws power from the
> cord or Onan as available, but it looks like there's more to it than just
> that. I shoved my phone in to take some pictures that I'll post to the
> photo site that show a blue box called Gen-Switch and another blue box
> called
> PowerGuard both from Trans-Tech of Plano Texas. I suspect the issues I
> had with my old air conditioner may have been related to what I'm
> experiencing
> now.
>
> A cursory web search brought up little for Trans-Tech of Plano, so I'm
> hoping someone here might have a memory of what this kind of thing is.
> Without
> air conditioning we are not happy campers.
>
> Alternately what would you replace this with? Is there current tech that
> might be compelling enough to rip it out and upgrade?
> --
> Larry Davick
> A Mystery Machine
> 1976(ish) Palm Beach
> Fremont, Ca
> Howell EFI + EBL + Electronic Dizzy
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>


--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org



Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
Re: No AC for my A/C! [message #347182 is a reply to message #347177] Sun, 01 September 2019 20:36 Go to previous messageGo to next message
Tom Lins is currently offline  Tom Lins   United States
Messages: 372
Registered: February 2004
Location: St Augustine, FL
Karma: 1
Senior Member
ljdavick wrote on Sun, 01 September 2019 20:46
I'm an unhappy, sweaty, middle-aged, suburbanite who can not seem to figure out why I have no power to the roof Air Conditioner. I have one roof air - in front - and it's a newer Atwood uint. Checking for power at the unit I found it was dead. I checked the overhead plug in the rear hallway ceiling - power. Still I checked the breakers. They operate as expected and current is running when on, not when off. So that's good.

My beloved PO had installed an automatic switch that draws power from the cord or Onan as available, but it looks like there's more to it than just that. I shoved my phone in to take some pictures that I'll post to the photo site that show a blue box called Gen-Switch and another blue box called PowerGuard both from Trans-Tech of Plano Texas. I suspect the issues I had with my old air conditioner may have been related to what I'm experiencing now.

A cursory web search brought up little for Trans-Tech of Plano, so I'm hoping someone here might have a memory of what this kind of thing is. Without air conditioning we are not happy campers.

Alternately what would you replace this with? Is there current tech that might be compelling enough to rip it out and upgrade?
Larry
Are you plugged into shore power or are you running the generator?
If you are plugged into shore power have you checked to see if you have power on both hots?
Was the air conditioner working before and now it does not?


Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
YOUTUBE Channel: GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
Re: No AC for my A/C! [message #347183 is a reply to message #347177] Sun, 01 September 2019 20:55 Go to previous messageGo to next message
ljdavick is currently offline  ljdavick   United States
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
Senior Member
I've copied the pictures up to the photo site

http://www.gmcmhphotos.com/photos/g7242-110v-switches.html
<http://www.gmcmhphotos.com/photos/g7242-110v-switches.html>

Replies

Jim - It's a 1976 Palm Beach

Matt - Any reason? I can't think of one reason - (fat, modestly skilled, uncertain, time constrained, uncomfortable working position!)

Tom - Both with the Generator and on shore power. The air conditioner had worked (beautifully) in the past. There were times when it would work intermittently and I always figured it was waiting for the caps to load up or some other magic smoke.

It took me some time to appreciate the automatic Generator Switch, as I'd heard others talking about plugging in the Onan / shore power cable. I don't bother with that, I just plug in to shore power when it's available or run of the Onan when needed.


Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
Re: No AC for my A/C! [message #347185 is a reply to message #347183] Sun, 01 September 2019 22:31 Go to previous messageGo to next message
Tom Lins is currently offline  Tom Lins   United States
Messages: 372
Registered: February 2004
Location: St Augustine, FL
Karma: 1
Senior Member
ljdavick wrote on Sun, 01 September 2019 21:55
I've copied the pictures up to the photo site



Tom - Both with the Generator and on shore power. The air conditioner had worked (beautifully) in the past. There were times when it would work intermittently and I always figured it was waiting for the caps to load up or some other magic smoke.

It took me some time to appreciate the automatic Generator Switch, as I'd heard others talking about plugging in the Onan / shore power cable. I don't bother with that, I just plug in to shore power when it's available or run of the Onan when needed.
Larry
I installed an automatic transfer switch on our previous GMC but haven't gotten to that on this one yet. It is nice not having to not worry about the plug.
I wonder if you have a bad breaker or possibly one leg of your breaker panel is not getting power from the transfer switch?



Tom Lins
St Augustine, FL
77 GM Rear Twin, Dry Bath, 455, Aluminum Radiator Quad-Bag Suspension Solar Panel
Manuals on DVD
YOUTUBE Channel: GMC Dealer Training Tapes
http://www.bdub.net/tomlins/
Re: No AC for my A/C! [message #347186 is a reply to message #347185] Sun, 01 September 2019 23:52 Go to previous messageGo to next message
ljdavick is currently offline  ljdavick   United States
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
Senior Member
Tom,

We think alike. I tested with the Onan all of the breakers and then on shore power. They were all hot. I think I may do what Matt suggests and dig into that blue box and undo what my beloved PO has done.

Sadly this has sent me down a path looking at RV Power centers. Like a kid in a candy store it's difficult to resist, but I have too many half done project now to begin something like this.

I'd like to hear what others have done, though.


Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
Re: [GMCnet] No AC for my A/C! [message #347188 is a reply to message #347186] Sun, 01 September 2019 23:57 Go to previous messageGo to next message
jimk is currently offline  jimk   United States
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
Senior Member
Larry,
Our electrician might be able to look at it solve your problem.
Let me know as he is very good at AC current.

On Sun, Sep 1, 2019 at 9:53 PM Larry Davick via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Tom,
>
> We think alike. I tested with the Onan all of the breakers and then on
> shore power. They were all hot. I think I may do what Matt suggests and
> dig
> into that blue box and undo what my beloved PO has done.
>
> Sadly this has sent me down a path looking at RV Power centers. Like a
> kid in a candy store it's difficult to resist, but I have too many half done
> project now to begin something like this.
>
> I'd like to hear what others have done, though.
> --
> Larry Davick
> A Mystery Machine
> 1976(ish) Palm Beach
> Fremont, Ca
> Howell EFI + EBL + Electronic Dizzy
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>


--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org



Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
Re: No AC for my A/C! [message #347189 is a reply to message #347183] Mon, 02 September 2019 00:04 Go to previous messageGo to next message
roy1 is currently offline  roy1   United States
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
Senior Member
Modernizing your coach to a transfer system is a nice upgrade but the old way of plugging and unplugging the shore plug is foolproof as far as simplicity is concerned . The transfer switches are generally a couple of double pole relays . I would remove the covers and check for loose connections burnt contact points or possibly a bad relay coil. Also check on line for the wiring diagram of your transfer switch it will help you trouble shoot the circuits. Does it operate with the generator? Did you loose all power or just the a/c unit?

Roy Keen Minden,NV 76 X Glenbrook
Re: No AC for my A/C! [message #347190 is a reply to message #347177] Mon, 02 September 2019 01:11 Go to previous messageGo to next message
ljdavick is currently offline  ljdavick   United States
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
Senior Member
Curiosity got the better of me. Thinking of Matt's suggestion I pulled off the cover plate and sure enough that Power Guard is connected to the Air Conditioning and the water heater circuits. I've disconnected the Air Conditioning side and wired it up. I don't have shore power out to the coach but I'll light up the Onan in the morning and see if I now have power to the air conditioner.

Or if I fry the coach. Either one would be exciting...


Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
Re: [GMCnet] No AC for my A/C! [message #347193 is a reply to message #347190] Mon, 02 September 2019 06:37 Go to previous messageGo to next message
Ken Henderson is currently offline  Ken Henderson   United States
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
Senior Member
Larry,

I think you've found it. I was going to second Matt's suggestion.
Certainly, it's smart to eliminate add-ons, as you've done, before tearing
into OEM equipment which has apparently been working well -- or add-ons
like the transfer switch which has obviously been transferring between
shore and Onan according to your other tests.

I suspect the "Power Center" was installed to overcome a problem with the
shore (or maybe the on-board Main) breaker popping when both the a/c and
the water heater came on at the same time. I'll bet you can deal with
that, by turning off the water heater, better than you can do without a/c!

Ken H.


On Mon, Sep 2, 2019 at 2:13 AM Larry Davick via Gmclist <
gmclist@list.gmcnet.org> wrote:

> Curiosity got the better of me. Thinking of Matt's suggestion I pulled
> off the cover plate and sure enough that Power Guard is connected to the Air
> Conditioning and the water heater circuits. I've disconnected the Air
> Conditioning side and wired it up. I don't have shore power out to the
> coach
> but I'll light up the Onan in the morning and see if I now have power to
> the air conditioner.
>
> Or if I fry the coach. Either one would be exciting...
> --
> Larry Davick
> A Mystery Machine
> 1976(ish) Palm Beach
> Fremont, Ca
> Howell EFI + EBL + Electronic Dizzy
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org



Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
Re: No AC for my A/C! [message #347197 is a reply to message #347177] Mon, 02 September 2019 08:53 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
Senior Member
It seems, if I am understanding your given info, that ONLY the roof circuit in non-op, Unless that is the only item on that leg of shore power and everything else works on board, that it may just he that roof breaker. On ACV if you meter line to load on that breaker you should have zero if breaker is closed. You can also meter before the breaker to N If you have power there but not after the breaker, it's the breaker. If you have power after but not at roof, it's connection or branch wiring. If no power before the breaker check main and switch over system If it's breaker, some aggressive exercise of the trip lever may get you by until it can be replaced.

John Lebetski
Woodstock, IL
77 Eleganza II
Re: No AC for my A/C! [message #347204 is a reply to message #347177] Mon, 02 September 2019 10:32 Go to previous messageGo to next message
ljdavick is currently offline  ljdavick   United States
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
Senior Member
Matt earns a gold star today! I waited for the neighborhood to wake up before lighting up the Onan and I now have power to the Atwood. I'd forgotten what a wonderful Air Conditioner it is and as a test I tried it in heat mode too. I believe it's a heat pump, so it takes a moment to gather itself before pumping out heat, but it's effective as a heater too.

Thank you to each of you who replied with such thoughtful responses.


Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
Re: No AC for my A/C! [message #347242 is a reply to message #347204] Mon, 02 September 2019 19:11 Go to previous messageGo to next message
roy1 is currently offline  roy1   United States
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
Senior Member
If that trans tech unit is just a lock out relay for the water heater and a/c unit all is good with it removed. You don't want to wire around a transfer unit which I assume is somewhere close by it would be bad if shore power back fed into the generator

Roy Keen Minden,NV 76 X Glenbrook
Re: No AC for my A/C! [message #347244 is a reply to message #347242] Mon, 02 September 2019 19:38 Go to previous message
ljdavick is currently offline  ljdavick   United States
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
Senior Member
Oooooh. I'll check the generator next time I'm plugged in to shore power, or vice versa...

Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
Previous Topic: [GMCnet] Steering Wheels
Next Topic: [GMCnet] Steering Wheels
Goto Forum:
  


Current Time: Tue Sep 24 01:31:26 CDT 2024

Total time taken to generate the page: 0.01100 seconds