Coleman rooftop a/c

[Bamshell]

Does anyone have experience with the coleman mach rooftop ac units? I replaced Both units today with brand new ones. The zone 1 front a/c works as it should. The rear zone 2 unit does what the old one did which is the fan coning on in cool mode but the compressor does not engage. In heat mode (both are heat pumps) front works as it should, rear doesnt even come on at all. Wondering if this is a tstat problem or a control board on the unit. New one doesnt come with this, the old one is used. Thanks for any help

[dougrainer]

Bamshell wrote:
Finally fixed!! After buying a new control board and 2 thermostats it ended up being a $20 temp sensor for the coil which was actually the very first thing i looked at.. i tested both for continuity and neither had it so i ruled it out because 1 unit was working fine. Turns out i needed to ohm it out. The giod one had 11k ohms and the other was 80k ohms.. i swapped them out and then the unit worked.. in hind sight i see why it would let the heat pump come on and not the a/c. 6 hrs of trouble shooting and it was the very first thing i looked at. Oh well hope this helps someone!

You said in your first post HP function, the compressor would not come ON. Now you say it worked in HP mode but not in COOL mode. Doug

You state TEMP sensor for the coil. Do you mean the FREEZE sensor installed in the evaporator? If so, that part is NOT supplied when replacing a complete upper unit. And yes, that defective part will keep the compressor from running.

[Bamshell]

Finally fixed!! After buying a new control board and 2 thermostats it ended up being a $20 temp sensor for the coil which was actually the very first thing i looked at.. i tested both for continuity and neither had it so i ruled it out because 1 unit was working fine. Turns out i needed to ohm it out. The giod one had 11k ohms and the other was 80k ohms.. i swapped them out and then the unit worked.. in hind sight i see why it would let the heat pump come on and not the a/c. 6 hrs of trouble shooting and it was the very first thing i looked at. Oh well hope this helps someone!

[jaycocamper6230]

swap control boards and watch the problem follow the board and then buy a new board on Amazon. Been there done that. I bet thats your problem

[dougrainer]

https://www.amazon.com/Coleman-83305191-Room-Sensor/dp/B019QH3QVC/ref=pd_lpo_1?pd_rd_w=vyZv9&content...

It looks like this and can be brown also. It is usually located in the rear bedroom area on the wall. Some OEM's install on the ceiling, but this old of a RV it is probably on the wall or bottom of a bedroom overhead cabinet. Lack of or a bad sensor would not cause the problem he has. Doug

[mfinnerty]

I have a dumb question. Where is the temp sensor for the rear or what triggers the rear ac/heat pump or furnace to turn on? Maybe the answer points to the solution. Both my last MH and my current MH have thermostats in the front and rear.

[dougrainer]

Bamshell wrote:
Thanks for all of the replies! Im leaning towards it being the tstat and here is why.. zone 2 is the back unit and if i switch to heat pump neither the compressor or the fan comes on. I am plugged into 50 amp ac now btw. If i go to cool, the fan comes on, no compressor. Also i just fired up my LP furnace and zone 1 seems to work perfect. When i try zone 2 on the gas heat it does nothing. I can tell there must be a separate fan for the rear zone because i have vents down low with no air flow coming out.. any feedback is greatly appreciated

At this point, you need to access your upper rear AC/HP control board. Check for loose or burnt wiring. You also need to check for 12 volts TO THE REAR FURNACE. The furnace is a separate appliance that is controlled thru the RVP tstat system. Did you replace the upper units or did a shop replace them? Either way, wiring may have been knocked loose when the upper control board was moved out of the way to replace the unit.

You can manually SWAP Zone 1 and Zone 2 at the front upper control board to test tstat operation for the rear HP. This link shows the ZC tstat wiring. Doug

https://www.airxcel.com/DesktopModules/RvProduct/Pdf/8330b331_8330b335_thermostat.pdf

[Bamshell]

Thanks for all of the replies! Im leaning towards it being the tstat and here is why.. zone 2 is the back unit and if i switch to heat pump neither the compressor or the fan comes on. I am plugged into 50 amp ac now btw. If i go to cool, the fan comes on, no compressor. Also i just fired up my LP furnace and zone 1 seems to work perfect. When i try zone 2 on the gas heat it does nothing. I can tell there must be a separate fan for the rear zone because i have vents down low with no air flow coming out.. any feedback is greatly appreciated

[dougrainer]

Your system (2005)

ENERGY MANAGEMENT SYSTEM -
SO AMP
Intellitec's Smart Energy Management System -
50 AMP (Smart EMS) is designed to be used in
RV s equipped with 50 AMP electrical service.
The system senses when the coach is connected
to a 50 AMP service or operating from the generator and allows simultaneous operations of all
the 120 volt loads. When 50 AMP service is not
available and the coach is connected to a smaller
electrical service, such as 30 or 20 AMP, the system automatically takes control of the loads to
practically eliminate circuit breaker tripping. It
constantly monitors the total amount of current
drawn in the RV and controls the loads, as necessary, to keep the total current to a value less than,
or equal to, the available power service.
There is no programming necessary and the unit
will work with any load within the circuit
breaker limits. The Smart EMS automatically
"learns" the amount of current drawn by each of
the controlled loads as it turns them on and off.
In this way, it automatically adapts to differing
loads or loads whose current changes with line
voltage or temperature.
Features:
• Limits total current to 30 AMPs.
• Minimizes circuit breaker tripping when
connected to 20, or 30 AMP service.
• Eliminates manual appliance select
switches.
• Senses current of owner added loads.
• Owner selectable 20 AMP operation from
remote panel.
• Protects air conditioners with two minute
restart delay.
• "Learns" controlled appliance current draw

Click this link for an in depth explanation.

https://intellitec.com/wp-content/uploads/2022/07/53-00894-600-1.pdf

[dougrainer]

When you do not have 50 amp service, just run your Generator to utilize it. Remember, on your year model, the EMS KNOWS if you are NOT ON 50 amp service and will kick out the bedroom Compressor from running. Your wall EMS display should show that. Doug

[Bamshell]

I believe i have the ems system you speak of, ill take a look. Will need to figure out how to use it if so

[Bamshell]

2005 fleetwood expedition
Both were heat pumps when i removed them and i put heat pumps back in. I have only 1 tstat that does both zones. I haven't tried plgging in the 50 amp setup yet. I am new to the sport so im taking in a lot of info. Thanks!

[dougrainer]

Were the original roof top AC's Heat Pumps? Some Oem's install a Heat Pump in front and a standard AC in the rear. You just joined. ALWAYS list
1. Year Make and Model of RV
2. Brand and model number of appliance you are asking about.
It is rare for a RVP(Coleman) top control board to fail.
It is also rare for the wall Tstat to fail.
Since the new HP does exactly as the old, it points to the control board/wall tstat/WIRING at the tstat or at the connections on the control board. Do you have 2 wall tstats or just 1 that controls both? Do BOTH tstats(if 2) have the same designations on the outer button cover?
On Coleman HP's, IF you set the HEAT to more than 5 degrees above the wall setting, the System defaults to the furnace. IF you have 2 furnaces. If just one furnace the front HP will default to furnace. The rear will do nothing except blow air. SO, try setting the rear tstat to just 3 degrees above what the tstat setting is. Doug

[wa8yxm]

Very good chance it's NOT either the AC or the T-stat

Do you have in intelletec EMS (Energy Manageent System) It can do that. if you are on 30 amp.. it can fail if you are on 50 and do it...

But if you do not then Id go with the T-Stat more than the A/C's since they are new. or the wires connecting (mis-wire or broken wire)

I like Coleman's by the way.. They SUCK. (most blow) and that makes them way way way way easier to clean.

[joelc]

I have a 2012 5er. I have a Coleman heat pump in the front and a/c in the rear. The t-stats are different. One has "heat" setting. If you have 2 heat pumps be sure the t-stats are both for the heat pump and one not just Air only. Otherwise, I can't help. You might check the connections on the one that works with the one that doesn't to see if they are both the same. Also, if old pump in the rear was A/C and now a Heat pump the wire gauge and/or breaker might be different. Good Luck!