Coleman Mach 8232 series to Atwood
I have two ancient (2003) Coleman A/C units which are ready for replacement. The system is run by the Intellitec 00-00591-200 controller and a no-longer-available Climate Controller also by Intellitec...
Forum Discussion
On further looking, I think I missed the 12 vdc supply for each that is needed by the Atwood and not used by the Coleman (as mentioned by others). There is a light adjacent to each of the A/C mounting holes from which I can tap the 12 vdc. I am not sure what uses this power, but I can get it easily if needed.
My current thinking is to mount the bedroom A/C thermostat in the bedroom on the bathroom/bedroom wall. This area is easily accessible from the area where the Intellitec controller is located. If the other thermostat cannot be placed on the wall near the entry door, I will consider placing it near where the temperature sensor for the Intellitec unit in the main coach is located. That area also has an access hole where I ran wires for extra outlets all the way from the rear of the camper and should provide access to that wall to string the Atwood cable.
The issue that I see is that the Intellitec unit expects to control the compressor and the fan. I think that it will require that the output of the Intellitec be accessible to provide the input for the Atwood which could mean that power from the Atwood to its compressor would have to intercepted by the Intellitec's output if the compressor was not allowed to run due to shedding. This could be done using a opto isolator or another relay local to the thermostat. The Atwood thermostat would operate the A/C compressor as long as the Intellitec compressor line for that A/C provided power to the relay to allow it to do so.
The On/Off switch for the thermostat would receive power from the Intellitec's power on wire that used to operate the thermostat on the Intellitec.
The Fan speed and all the features of the Atwood would operate from the Atwood thermostat and be turned off by the Intellitec for shedding purposes. The fan supply would be provided by the high speed fan output of the Intellitec and used to intercept the fan operation of the Atwood - it might take three more devices to provide shedding for the fans because of the three speeds. It will depend on whether or not the Atwood thermostat can be modified easily to allow one input for all three fan operations (which I doubt). So the outputs will have to be intercepted by relays or opto isolators similar to the compressor. This again is to provide the shedding function by killing the power to the fans. If the Intellitec power is not available, the Atwood output to the A/C would be intercepted. That would mean a total of eight mini relays or opto isolators.
The power to the Atwood A/Cs will not shed properly if the Atwood thermostat is turned off altogether.
The furnace would continue to be operated by the Intellitec thermostat. In fact, I don't think that the feed from the Atwood for the furnace makes much sense. It appears that the Atwood switches to furnace when it is unable to operate efficiently. But then it requires that you turn off the A/C fan and switch on the furnace using the switch on the Atwood thermostat. Whichever way, I will have the wires necessary to allow the power to the furnace to go through the Atwood A/C's relay and then have the furnace switched on so that when the relay picks the furnace will run using the setting on the Intellitec thermostat which will remain in place along with its thermistors.
So most of the work needs to be done behind the power panel in the bedroom. I am considering the removal of the 13" CRT TV and replacing it with a TV with blu ray player. If I did that, I could possibly move the Intellitec controller from behind the power panel into an area where it is more accessible (it actually has a test feature that is basically unusable where it is located) and put the new electronics into a black box where I will be able to get at all of the system. The transfer box would remain where it is.
My current thinking is to mount the bedroom A/C thermostat in the bedroom on the bathroom/bedroom wall. This area is easily accessible from the area where the Intellitec controller is located. If the other thermostat cannot be placed on the wall near the entry door, I will consider placing it near where the temperature sensor for the Intellitec unit in the main coach is located. That area also has an access hole where I ran wires for extra outlets all the way from the rear of the camper and should provide access to that wall to string the Atwood cable.
The issue that I see is that the Intellitec unit expects to control the compressor and the fan. I think that it will require that the output of the Intellitec be accessible to provide the input for the Atwood which could mean that power from the Atwood to its compressor would have to intercepted by the Intellitec's output if the compressor was not allowed to run due to shedding. This could be done using a opto isolator or another relay local to the thermostat. The Atwood thermostat would operate the A/C compressor as long as the Intellitec compressor line for that A/C provided power to the relay to allow it to do so.
The On/Off switch for the thermostat would receive power from the Intellitec's power on wire that used to operate the thermostat on the Intellitec.
The Fan speed and all the features of the Atwood would operate from the Atwood thermostat and be turned off by the Intellitec for shedding purposes. The fan supply would be provided by the high speed fan output of the Intellitec and used to intercept the fan operation of the Atwood - it might take three more devices to provide shedding for the fans because of the three speeds. It will depend on whether or not the Atwood thermostat can be modified easily to allow one input for all three fan operations (which I doubt). So the outputs will have to be intercepted by relays or opto isolators similar to the compressor. This again is to provide the shedding function by killing the power to the fans. If the Intellitec power is not available, the Atwood output to the A/C would be intercepted. That would mean a total of eight mini relays or opto isolators.
The power to the Atwood A/Cs will not shed properly if the Atwood thermostat is turned off altogether.
The furnace would continue to be operated by the Intellitec thermostat. In fact, I don't think that the feed from the Atwood for the furnace makes much sense. It appears that the Atwood switches to furnace when it is unable to operate efficiently. But then it requires that you turn off the A/C fan and switch on the furnace using the switch on the Atwood thermostat. Whichever way, I will have the wires necessary to allow the power to the furnace to go through the Atwood A/C's relay and then have the furnace switched on so that when the relay picks the furnace will run using the setting on the Intellitec thermostat which will remain in place along with its thermistors.
So most of the work needs to be done behind the power panel in the bedroom. I am considering the removal of the 13" CRT TV and replacing it with a TV with blu ray player. If I did that, I could possibly move the Intellitec controller from behind the power panel into an area where it is more accessible (it actually has a test feature that is basically unusable where it is located) and put the new electronics into a black box where I will be able to get at all of the system. The transfer box would remain where it is.
