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Air Conditioner /thermostat


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A couple months ago I posted a question in regards to my front /Galley thermostat zone 3, I have not used the coach since November,  did some repairs , always plug in, started regularly and so on, long story short, I think Richard responded and mentioned to clean the telephone cables at the air conditioner and thermostat,  I did spray a electronic cleaner, today I turn it on, the screen has a display for say 10 seconds and goes out, so I have not solved the problem, I do have another dometic thermostat (new) that I put in and nothing, it seems to work when it wants to, It would be nice to have the front Air working, I am more concerned about the heat in that join once we start to travel in the Fall, any suggestions would be appreciated. 

Man I miss John!

Thanks

Wayne

1999 Signature Caesar 

 

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Richard is still probably correct about the phone cables,  but just spraying is not likely to get the job done.   You'll need to at least unplug and plug back in a few times

to hopefully clean the metal contacts.

BTW,  who is John? 

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3 minutes ago, wayne.cerven@gmail.com said:

Thanks guys

I did open and cleaned the connection at the air conditioner, I will try to clean them up some more at both ends.

Ray ,I was talking about John Haggard 

Wayne 

1999 Signature Caesar 

Thanks Wayne,  Sorry I didn't make the connection.   I miss John too.   We are losing to many.

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Wayne, do you still have the original 1999 four button thermostats?

They are very unreliable and many of us converted these older A/C systems to the five button thermostats.  

When you plug in a new/different thermostat it must be programmed to the A/C control boards.  There is a small black switch on the bottom.  First, slide it to off.  Then plug in the RJ11 telephone cable.  

Simultaniously depress both the top and bottom push buttons and slide the on/off switch on.  You should see "FF" in the display window.  

Now you can select A/C and the desired temperature. 

Another caution.  It takes 5 min for the system to respond to changes in thermostat settings.  

DeOxit is the best electrical cleaner I've found.

https://www.amazon.com/Hosa-D5S-6-DeoxIT-Contact-Cleaner/dp/B00006LVEU/ref=sr_1_4?dchild=1&keywords=deoxit&qid=1630451763&sr=8-4

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Vito

Yes I am still using 4 button controller, I did buy the new one you are describing,  I will follow your instructions in the morning with a coffee and it should work.I bought the new one in Minneapolis before COVID and the guys in the parts department had no Idea how to program it to the Air Conditioner,  now that you say that I remember the FF coming up but did not understand what to do next, may have read the instructions at some point and seen that but been so long who knows!

Thank you very much

Wayne 

1999 Signature Caesar 

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No it's not that easy.  The A/C control board (up inside the A/C on the roof) version much match the thermostat version.  

So if your roof A/C units are original they must be controlled by an original four button thermostat.  

Dometic used to make a conversion control board so you could install the 5 button thermostat and a new 5 button conversion control board into your older A/C.  I don't think they make it any longer.  

Dometic switched from the 4 button system to the 5 button Comfort Control (CC) system around 2002. 

It gets better!

A few years ago Dometic updated everything again.  The newest thermostat is a CCII (Comfort Control II) programmable thermostat and A/C system.  These are also not backwards compatible.  They do make a conversion control board to use a new A/C with a 5 button thermostat, but not a conversion for the 4 button.  

So, you have some choices.  You can have your old 4 button thermostat rebuilt.  Check eBay. 

REPAIR SERVICE for YOUR Duo Therm 4 Button Thermostat Dometic Part# 3106463007 | eBay

Dometic Duo-therm 4 Button Thermostat Replacment Buttons / Switches DIY Repair | eBay 

Or, you can buy a brand new A/C and a new CCII thermostat.  And, if you have two A/C's on one thermostat they must both be updated.  These new systems still use the same RJ11 telephone style control cable.  

Hope this helps!

 

Edited by vito.a
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Morning 

Thanks Vito

Just spoke to the gentleman that repairs them, he told me to try the on/off switch usually come loose and the back to make sure everything is secure,going to send him both switches over the winter to rebuild.  Air conditioner's still work great so won't spend the big dollars until one of the main ones goes done.

Thanks for the great info/ connection

Wayne 

1999 Signature Caesar 

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10 hours ago, vito.a said:

No it's not that easy.  The A/C control board (up inside the A/C on the roof) version much match the thermostat version.  

So if your roof A/C units are original they must be controlled by an original four button thermostat.  

Dometic used to make a conversion control board so you could install the 5 button thermostat and a new 5 button conversion control board into your older A/C.  I don't think they make it any longer.  

Dometic switched from the 4 button system to the 5 button Comfort Control (CC) system around 2002. 

It gets better!

A few years ago Dometic updated everything again.  The newest thermostat is a CCII (Comfort Control II) programmable thermostat and A/C system.  These are also not backwards compatible.  They do make a conversion control board to use a new A/C with a 5 button thermostat, but not a conversion for the 4 button.  

So, you have some choices.  You can have your old 4 button thermostat rebuilt.  Check eBay. 

REPAIR SERVICE for YOUR Duo Therm 4 Button Thermostat Dometic Part# 3106463007 | eBay

Dometic Duo-therm 4 Button Thermostat Replacment Buttons / Switches DIY Repair | eBay 

Or, you can buy a brand new A/C and a new CCII thermostat.  And, if you have two A/C's on one thermostat they must both be updated.  These new systems still use the same RJ11 telephone style control cable.  

Hope this helps!

 

I guess I could take the thermostat from the bedroom to the galley to test wether it is a thermostat issue, correct? 

Thanks

Wayne 

1999 Signature Caesar 

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21 hours ago, vito.a said:

Great idea but it will need to be programmed each time you move it.

Morning 

I had zone 3 running great, do not think it is the thermostat, this morning I fired up the Aqua hot,let it warm up for a while and turned on Zone 3 (galley) all good, went back into the bedroom and turned on Zone 1 and then thats when zone 3 thermostat went blank again and power off ? Programming problem, something else?

Thanks 

Wayne 

1999 Signature Caesar 

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The front zone 3 should not be connected with the two rear zones.  Maybe coincidence?

Zones are determined by small dip switches on each A/C control board.  When the thermostat is programmed, it picks up the dip switch setting and displays the selected zone. 

The very front should have its own thermostat and the two rear zones are ganged together on one thermostat.  There should not be any interconnection between front the two rear.  

Just a wild guess.  How old are your house batteries?  Clean the terminals and check the voltage at the batteries.  I say this because the thermostats run on 12v.  

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55 minutes ago, vito.a said:

The front zone 3 should not be connected with the two rear zones.  Maybe coincidence?

Zones are determined by small dip switches on each A/C control board.  When the thermostat is programmed, it picks up the dip switch setting and displays the selected zone. 

The very front should have its own thermostat and the two rear zones are ganged together on one thermostat.  There should not be any interconnection between front the two rear.  

Just a wild guess.  How old are your house batteries?  Clean the terminals and check the voltage at the batteries.  I say this because the thermostats run on 12v.  

Batteries are going on 4 years, fully charged, everything clean,everything else you said is correct,going to check batteries again

Thanks 

Wayne 

1999 Signature Caesar 

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1 hour ago, vito.a said:

The front zone 3 should not be connected with the two rear zones.  Maybe coincidence?

Zones are determined by small dip switches on each A/C control board.  When the thermostat is programmed, it picks up the dip switch setting and displays the selected zone. 

The very front should have its own thermostat and the two rear zones are ganged together on one thermostat.  There should not be any interconnection between front the two rear.  

Just a wild guess.  How old are your house batteries?  Clean the terminals and check the voltage at the batteries.  I say this because the thermostats run on 12v.  

Just thought, how could it be a 12 volt issue when the coach is plugged into the house? 

Thanks

Wayne 

1999 Signature Caesar 

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The 12 volt system is supplied by the coach battery system.  The inverter charges the batteries when plugged in or on generator.  But, if the batteries are bad or going bad 12v can be intermittent.  

All the lights are 12v as well as the A/C controls.  

Edited by vito.a
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Ray

Funny ,I found that same thread on Friday, cleaned up the thermostat and fingers crossed seems to be working, going to try it on a short trip at the end of the week, if it acts up we have a specialty electronic shop in town that I will take it to and have them have a look, they said they have repaired thermostat before, going to print the thread and take it with me for their review. 

Thanks

Wayne 

1999 Signature Caesar 

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