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Topic: No power to inside thermostat (Read 1955 times) previous topic - next topic

No power to inside thermostat

Inside thermostat no power. Just replaced bothe run capacitors up top and they were a bugger to get out manipulating it past the circuit board. Got them in  and fired up generator to test. Turned breaker on for ac and the salesman switch on. Thermostat wil not power up inside. Dis i do something with the circuit board ??  Is there a fuse i blew for the 5 button thermostat. Help please??!!
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

Re: No power to inside thermostat

Reply #1 –
Take a good look at the circuit board. I shorted mine out and had to replace it and the damage was visible.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: No power to inside thermostat

Reply #2 –
Ok so got it going but the thermostat is blank on zone 2 (rear ac). BUT both ac units are working.... And running. Do the dip switches have to be in the same configuration for both?  Why would mt thermostat light up and show zone 1 but not 2?
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

Re: No power to inside thermostat

Reply #3 –
There is a bad connection in the j11 connector to the rear ac and it can be at the front ac or at the rear ac.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: No power to inside thermostat

Reply #4 –
Does anyone know the dip switches settings for my 2 dometic acs with the 5 button thermostat

I cant get anything but zone 2 and switched some dip switches to no avail
Still only see zone 2 on the thermostat
Dip switches are heat strip off zone 2 and 3 on zone 4 off furnace on and the rest off
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

Re: No power to inside thermostat

Reply #5 –
The front one should have furnace on and if a heat strip then that on. On the rear zone 2 on furnace on and depending if there is a heat strip that could be turned on.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: No power to inside thermostat

Reply #6 –
That works for the aquahot??
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

Re: No power to inside thermostat

Reply #7 –
Yes, the thermostat controls both the ac and the aqua hot.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: No power to inside thermostat

Reply #8 –
Well no luck. Giving up on it today. Think the rj11 cables are good. Am planning on setting the dip switches  the same on front and rear ac units tomorrow-heat strip  off zone 2 3 and 4 on.  Furnace on and the rest off
Will see if it works
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

Re: No power to inside thermostat

Reply #9 –
FYI
In conversation with Dometic this AM they walked me through the dip switch setup with 2 AC( 620315) 2 new control boards, (to go with the 5 button thermostat
) and aquahot
According to dometic with a 2 zone system on the thermostat the first AC (my front AC) is zone 1 and the rear is zone 2
Dip switch settings for front AC (zone 1) are :

ALL dip switch setting to the OFF position except the furnace dip switch which is set to the ON
position.

For the rear AC (zone 2 ) zone 2 dip switch settings to ON and the furnace dip switch set to ON
ALL other dip switches set to OFF

I admit i have not gone up on the roof yet to check this out but that is the Dometic tech giving advice

Anyone else have the same views???
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

Re: No power to inside thermostat

Reply #10 –

Get a RJ /Network cable tester or you are just guessing. I recently went through similar had it not been for a tester, I would have been chasing my tail.

What I would like to know.....At what location in the coach does your Aquahot wiring physically integrate in with RJ type connectors. The only cable on the back of my Thermostat is 1 RJ cable that goes up to the filter housing of my front unit From their RJ cables back to the rear roof unit.

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Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: No power to inside thermostat

Reply #11 –
Mine does the same thing goes from thermostat to front ac. Then a separate one goes to the second AC  Ordered the rj11 tester as you suggested. Will advise  the status if the cable for sure when i receive it from amazon
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

Re: No power to inside thermostat

Reply #12 –
Quote from: Peter –
Mine does the same thing goes from thermostat to front ac. Then a separate one goes to the second AC  Ordered the rj11 tester as you suggested. Will advise  the status if the cable for sure when i receive it from amazon

Yeah no issues with mine after replacing one of the RJ cables, but then got to thinking?....Hmmmm....just how and where does the Aquahot communication tie into this?
Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: No power to inside thermostat

Reply #13 –
Which one did you have to replace and how hard was it?
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

Re: No power to inside thermostat

Reply #14 –
If I remember correctly the aquat is tied to the blue wire. The the red and black wires hook up to the front ac.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: No power to inside thermostat

Reply #15 –
Quote from: red tractor –
If I remember correctly the aquat is tied to the blue wire. The the red and black wires hook up to the front ac.

BUT WHERE in the coach does this physically happen?

No RJ communication connectors down at my AH, and up where all the RJ connectors are ( inside both the front and rear AC filter box) there is nothing but RJ connectors. I am thinking going from front to rear filter boxes, that RJ cable must drop somewhere for the connection. Never had to think about it until my recent failure.
Mike in AL
2001 U295
8.3 ISC 350
Build 5918

Re: No power to inside thermostat

Reply #16 –
There are I believe 4 16 gauge wires coming out of the bottom of the ac. You remove the filter and look towards the front of the coach and on the front ac the wires are in a wire strap. Remove the strap and separate the wires. The blue wire is the one that activates the aqua hot. The red one is 12 volt positive and I don't remember if the black is the negative and one is not hooked up. On zone 2 the only one of those 4 wires that is hooked up is the blue which turns on zone 2 aqua hot. I am in the hospital right now, if I was home I could look at my Dometic manual.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: No power to inside thermostat

Reply #17 –
On my IH the thermostat has wires going to AH for each zone.  Thermostat tells AH to turn on or off.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago