Dometic AC Type

Mach428 · 02-01-2019, 07:28 AM

I have a 2012 3011DS with a Dometic rooftop AC unit. I thought that it was straight AC until last weekend while camping with the thermostat on FURNACE, the AC unit came on. It's never done that before. I'm wondering if this unit could also be a heat-pump.

There's absolutely no model number on this that I can see. Any thoughts? How do I tell?

**Mr. Dan** · 02-01-2019, 08:07 AM

Quote:

Originally Posted by Mach428

I have a 2012 3011DS with a Dometic rooftop AC unit. I thought that it was straight AC until last weekend while camping with the thermostat on FURNACE, the AC unit came on. It's never done that before. I'm wondering if this unit could also be a heat-pump.

There's absolutely no model number on this that I can see. Any thoughts? How do I tell?

If yours is typical of these symptoms reported often here, your AC compressor is not running — only the blower. Cycle your thermostat from Heat to Cool to Fan then use the + or - keys to cycle fan speed from Hi to Lo to Au for Auto. That will stop the AC blower from running with the furnace. It’s a feature used purposefully by some.

Mach428 · 02-01-2019, 08:16 AM

Great information. Thank you very much!

Mach428 · 02-01-2019, 08:43 AM

I just checked, it was already on AU. My question is how do I tell if this is a heat pump?

dustman_stx · 02-01-2019, 08:57 AM

Quote:

Originally Posted by Mach428

I just checked, it was already on AU. My question is how do I tell if this is a heat pump?

Does your thermostat have a heat pump setting? It'll either say heat pump or as you cycle through give you a heat pump icon.

dustman_stx · 02-01-2019, 08:58 AM

IF it's a 2012, it should have this type of thermostat (single zone LCD), clearly showing the Heat Pump option.

Mach428 · 02-01-2019, 10:36 AM

No it does not have that on the thermostat. That answers my question. Thank you

5picker · 02-01-2019, 10:55 AM

Quote:

Originally Posted by Mach428

I have a 2012 3011DS with a Dometic rooftop AC unit. I thought that it was straight AC until last weekend while camping with the thermostat on FURNACE, the AC unit came on. It's never done that before. I'm wondering if this unit could also be a heat-pump.

There's absolutely no model number on this that I can see. Any thoughts? How do I tell?

Had you ever camped in the past using the furnace while having an electrical hook-up?

As Mr. Dan mentioned about the A/C fan feature, (if so equipped) it only will operate that way when you have shore power. If boondocking or camping without a hook-up, the A/C blower will not run since it can only run off 120v AC

The furnace blower runs off 12v DC and always blows when using the furnace regardless of having shore power or not.

Being a 2012 model I would have thought you might have experienced this previously but then again maybe it is new to you?

Mach428 · 02-01-2019, 11:10 AM

Yes, I've camped countless times with and without shore power. The AC blower has never come on with the furnace. It was in the 40's so the furnace would cycle on and off as it should BUT this time, the AC blower would run as well.

5picker · 02-01-2019, 11:20 AM

Quote:

Originally Posted by Mach428

Yes, I've camped countless times with and without shore power. The AC blower has never come on with the furnace. It was in the 40's so the furnace would cycle on and off as it should BUT this time, the AC blower would run as well.

Here is a link to the manual of a Dometic Digital thermostat.

Pay special attention to the fan* mode operations on pages 7-8-9.
(NOTE: *they are describing the A/C fan)

Dometic Single Zone Thermostat

I'm guessing somehow the fan setting in the thermostat got changed somewhere along the line either manually (by someone) or reverted to a default setting by being disconnected for a period of time although I've always believed the default fan setting was AU-Auto.

Mach428 · 02-01-2019, 01:28 PM

Thank you so much 5picker

5picker · 02-01-2019, 01:37 PM

You are more than welcome.

And I'm sure some get sick of me saying this but since it seems we get these "A/C runs with the furnace" threads every week... the whole premise of the A/C fan running with the furnace option is to more evenly distribute the heat throughout the R/V.

Heat rises and since the A/C air intake is at the ceiling, using the A/C fan helps move the warmer air near the ceiling, throughout.

Some folks like it... some don't... and since it is just moving air (not heating it) some don't want the additional noise of the A/C fan. That is why there is an option to turn it off. Your choice.

Mach428 · 02-01-2019, 04:01 PM

Perfectly explained. It just never came on before and I haven't changed any thermostats settings. Oh well, now I know 😊

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