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Funny heat pumps…


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Since my AH zone one stopped working, I started using my heat pumps to warm the front of the coach. I’ve owned the coach nearly four years and haven’t ever used the heat pumps before now. 
 

If I turn on all three heat pumps while on 50 amp shore power, none of them start up. If I turn off the bedroom AC unit at the thermostat, the front two start and work well. I can only use the bedroom heat pump if the front two are off. Is this some kind of snafu?

Edited by Pduggs
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I can run all 3…04 Dynasty and 08 Navigator although I do not remember all 3 on at the same time as it doesn’t get that cold in SE Fla. Some units have load shedding with the dryer. 

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They all 3 should work at the same time.  The washer is tied to one AC, usually zone 2.  The dryer is 240V, so its separate.  

The heat pumps will not work if you have Furnace (Aqua Hot) selected on any other zone.  

We can get deeper when you have explored this.

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Posted (edited)

On my thermostat I have all three units set for heat pump. None will work with it set this way. If I shut off the rear AC (zone 3) the front two ACs run and heat well. I do have the AH buttons in the galley on.  

Edited by Pduggs
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Do you have the two original Dometic 5 button Comfort Control thermostats?  The front one controls the front AC and the rear controls the other two?

Will all three cool on AC?

Have you tried deselecting Aqua Hot electric on the kitchen Intellitec switch and then try the heat pumps?

Have any of your AC/Heat Pumps been replaced?

Are you certain all three are heat pumps?

Have you checked and reset all three AC circuit breakers?  

You can try a thermostat reset.  Turn off the black slide switch on the bottom (slide forward) of the thermostat.  Then simultaneously hold the top Mode button and the bottom Zone button while sliding the on/off switch on.  You will see FF in the display.  Reset both thermostats.  Select Heat Pump on all three zones.  Wait 5 min and all three should come on.   

If the above doesn't fix it, then the control board dip switches should be checked.  This is especially true if any have been replaced.  Turn the thermostats off before you make any dip switch changes and make sure you perform a reset after making changes. 

There's a row of small dip switches on each AC control board.  These determine the zone as well as if it's a heat pump or if it has an electric heat strip.  The control board is accessed from the roof.  Remove the plastic shroud, then a small metal cover on the right front of the AC.  The control board is inside and each switch is labeled.  All three should be checked to make sure the zones are set correctly (none of them have the same zone number and they are sequential) as well as the heat pump option is selected.  

For a diagram of the dip switches, look at Fig 23 (page 13) on these instructions:  6/14/18 640312 640315 CCC 2 3312020 Electronic Control Kit Ducted 3105007 Air Conditioner Installation Instructions (dometic.com)

Best of luck!

Edited by vito.a
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I have only one thermostat. Five button CCC. All three do cool okay. I will try to operate all three with the intelligtec AH switches off. All three units must have heat pumps because all have produced heat, just not at the same time. I’ve done the thermostat reset but nothing changed. I don’t believe any of my ACs were replaced, but I’m not certain. I bought the coach from the original owner who had it ten years. He never indicated any were replaced. 
 

I’ll check the dip switches. 

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We just got back to the coach this evening after being gone all day, I turn on all three heat pumps and all three work perfectly. I hadn’t run them in several days as it’s been too warm. 
 

Weird things happen with a motorhome. 

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  • 3 weeks later...

Please let me know if this is normal. My heat pumps will only run if the thermostat is set for “heat pump” on all zones. If I have any zone off or set for anything other than heat pump, none of three units will operate. 

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Doesn't sound correct to me. You should be able to run the heat pump just on whatever zone you choose without having to select heat pump on ALL zones first.

You didn't post what thermostat you are using but I assume it is the 5 button CCC or the 10 button CCC-2.

Are you positive that the dip switches are set correctly in the rooftop units for your specific setup?

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On 10/29/2021 at 9:05 AM, Pduggs said:

It’s the five button. 

I’ve not checked the dip switches. 

Are you seeing all 4 zones on the thermostat?  On my 08 Dynasty, Monaco had the dip switches on the 4th zone set incorrectly.  This caused all sorts of problems with how the heat pumps and AC units operated.  On my coach the control box for the 4th zone is located in a hidden panel behind the thermostat.

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54 minutes ago, Frank McElroy said:

Are you seeing all 4 zones on the thermostat?  On my 08 Dynasty, Monaco had the dip switches on the 4th zone set incorrectly.  This caused all sorts of problems with how the heat pumps and AC units operated.  On my coach the control box for the 4th zone is located in a hidden panel behind the thermostat.

Yes I see all four zones on my thermostat. My fourth zone is the bathroom. On the Squire, the fourth zone is the enclosed bathroom. 

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