Dometic A/C not shutting off

[andrew selkregg]

I have a 2015 3610 rl with Legacy package, 2 Dometic A/c units and one ccc2 thermostat. Most recent trip, I noticed that the bedroom A/C wasn't cycling off when the temp set point was reached. Pushing the "inside temp" button showed 69 and I raised the set point up to 90 and it still wouldn't shut off. Thermostat was set to COOL and fan on AUTO. The only way to shut it down was to set the thermostat to OFF for zone 2. I opened the 50 amp breaker at the power pedestal and removed and unplugged the thermostat, hoping a power cycle would straighten it out. No change. The other thing I noticed was that when turned ON, the bedroom A/C would start running immediately, instead of the usual 10 or so second delay.

Anyone had this issue and found the solution?

Thanks,

Andy

[twindman]

I think this is because of the Auto setting, perhaps. I think Auto has the fan running continuously. I may have this backwards tho. Something to try.

[ChuckS]

I also have two AC units.. both Dometic.. Zone 1 is HP unit and Zone 2 (BR) is 13.5 unit.. CCC2 thermostat controls both...

I have had the same issue a few times and to clear the error there are one of two ways that you can try...
1. Do a reset on the CCC2 thermostat and it should show Zone 1 and 2 after reset
2. If the issue still happens when Zone 2 AC reaches set point and BR unit wont shut off then do this to clear the "LATCHED RELAY" on the control module for the Zone 2 (BR) AC unit..

... remove shore power
... Put battery disconnect to OFF

You HAVE TO REMOVE the 12 volts that is being sent to BOTH control module units as well as thermostat to allow the relays to reset..

12 volts is present AT ALL times when either shore power OR battery power is connected to both AC units and thermostat

AFTER removing power ( 120 and 12 volt DC ) then turn battery disconnect back on and reconnect shore power and do another reset on the CCC2

The RESET lets the thermostat talk on the CANBUS to both Zone 1 and Zone 2 AC control modules and will reestablish communication along the CANBUS line..

This CANBUS line is simply the 4 wire telephone line that connects to back of CCC2 thermostat.. Red and black provide 12 volts DC to CCC2 and greens and yellow are the HI/LO CANBUS signals

[WeBeFulltime]

Set fan to "AUTO" and it will shut off when thermostat satisfied.

[ChuckS]

Originally Posted by WeBeFulltime

Set fan to "AUTO" and it will shut off when thermostat satisfied.

OP has the fan at AUTO.. the control module for that Zone 2 AC unit is latched and not sending the "temp satisified" signal down to the CCC2 to shut off OR the Zone 2 remote temp sensor has an issue.

[andrew selkregg]

Originally Posted by ChuckS

OP has the fan at AUTO.. the control module for that Zone 2 AC unit is latched and not sending the "temp satisified" signal down to the CCC2 to shut off OR the Zone 2 remote temp sensor has an issue.

I think Your explanation makes a lot of sense. I did most of your steps but did not disconnect the 12v switch in the convenience center or do the reset. I merely shut off 110v at the pedestal and removed the thermostat thinking it would reboot when I plugged it in and powered it up.
The trailer is in the storage lot now but I will get it home in the next few days and go through your procedure.
Thanks for the response.

Andy

[ChuckS]

Originally Posted by andrew selkregg

I think Your explanation makes a lot of sense. I did most of your steps but did not disconnect the 12v switch in the convenience center or do the reset. I merely shut off 110v at the pedestal and removed the thermostat thinking it would reboot when I plugged it in and powered it up.
The trailer is in the storage lot now but I will get it home in the next few days and go through your procedure.
Thanks for the response.

Andy

Even though you removed the CCC2 thermostat the roof AC unit control modules STILL have 12 volts DC to them from the battery at ALL times unless battery disconnect is turned off... The control module in Zone 1 is what sends 12 volts DC power down to the CCC2 thermostat on the telephone line...

BOTH zone 1 and Zone 2 control modules are piggy backed together via another telephone line that runs from Z1 to Z2 control modules and they both have 12 volts DC as long as a battery is present

The relays inside can become confused and LATCH and when this occurs the unit will continue to run because it cant see a command to turn off across the CANBUS line

[andrew selkregg]

Originally Posted by ChuckS

Even though you removed the CCC2 thermostat the roof AC unit control modules STILL have 12 volts DC to them from the battery at ALL times unless battery disconnect is turned off... The control module in Zone 1 is what sends 12 volts DC power down to the CCC2 thermostat on the telephone line...

BOTH zone 1 and Zone 2 control modules are piggy backed together via another telephone line that runs from Z1 to Z2 control modules and they both have 12 volts DC as long as a battery is present

The relays inside can become confused and LATCH and when this occurs the unit will continue to run because it cant see a command to turn off across the CANBUS line

Chuck,

That's apparently what happened, because as soon as I did your procedure, the A/C is running fine (and shutting off at the set point)

Thanks for your help. You have to love this Forum!

Andy

[ChuckS]

Originally Posted by andrew selkregg

Chuck,

That's apparently what happened, because as soon as I did your procedure, the A/C is running fine (and shutting off at the set point)

Thanks for your help. You have to love this Forum!

Andy

Glad to hear you got the AC unit working correct... Just remember the CANBUS is what is used to talk back and forth from thermostat to the AC units and furnace.. If either Zone gateway or control module gets a relay latched then your issue will occur

[Ronxs]

Having the exact same issue and will try your fix. Just became a new member because of wealthy information from experienced members like yourself. Thank you.

[Foldbak]

Originally Posted by Ronxs

Having the exact same issue and will try your fix. Just became a new member because of wealthy information from experienced members like yourself. Thank you.

Welcome to the MOC. Go to the intro page and introduce yourself.

https://www.montanaowners.com/forums...splay.php?f=28