A/C runs when fan and furnace are selected

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   Either I'm doing something wrong or my Dometic thermostat is wired wonky. 

Ever since I bought my unit a month ago I thought it was strange that if plugged into shore power, the A/C will run when only the fan is selected on the thermostat. Meanwhile, the furnace was fine, even up until this afternoon, running on its own without the A/C barging in. But this evening when I turned on the furnace, the A/C started running along with it. After a number of troubleshooting steps, I ended up just switching off the A/C at the breaker so the furnace can do its thing without working against the cold air of the A/C. 

Has this happened to anyone?

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howmanyds Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 07 Feb 2016 Location: Murrieta, CA Online Status: Offline Posts: 71	Topic: A/C runs when fan and furnace are selected Posted: 12 Apr 2016 at 11:36pm
	Either I'm doing something wrong or my Dometic thermostat is wired wonky. Ever since I bought my unit a month ago I thought it was strange that if plugged into shore power, the A/C will run when only the fan is selected on the thermostat. Meanwhile, the furnace was fine, even up until this afternoon, running on its own without the A/C barging in. But this evening when I turned on the furnace, the A/C started running along with it. After a number of troubleshooting steps, I ended up just switching off the A/C at the breaker so the furnace can do its thing without working against the cold air of the A/C. Has this happened to anyone?

Retroactive Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 15 Mar 2016 Location: Bolton, MA Online Status: Offline Posts: 270	Posted: 13 Apr 2016 at 7:22am
	If I remember correctly: set the fan to Auto, then go to furnace mode and select the temp.

furpod Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group - pHp Joined: 25 Jul 2011 Location: Central KY Online Status: Offline Posts: 6128	Posted: 13 Apr 2016 at 8:42am


Retroactive Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 15 Mar 2016 Location: Bolton, MA Online Status: Offline Posts: 270	Posted: 13 Apr 2016 at 9:04am
	Doesn't step #3 shut off the furnace? It sounds like he wants to run the furnace. I had the exact same problem. It all has to do with whether the Rpod is plugged into shore power, or running off battery. If the fan setting is on High or Low, the A/C fan does not turn on when running off of battery power; the pod sees no difference between the compressor and fan when running on battery, it simply does not power any of the A/C unit at all. However once plugged into shore power, if you are already have the furnace fired up, the A/C fan will pop on if not set to Auto already. Essentially what happens is that running on battery tricks the user into thinking that the fan is already set to Auto, because the A/C fan does not kick on until the second that you plug into shore power. So I believe he needs to follow #1 & #2 exactly per your pic; but then leave it on furnace in step #3, by using the on/off button to progress to the furnace light.

howmanyds Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 07 Feb 2016 Location: Murrieta, CA Online Status: Offline Posts: 71	Posted: 13 Apr 2016 at 12:41pm
	Yes! Ok, that makes sense now. Although I sometimes think the engineers at Dometic have a weird sense of humor. Thank you!

Retroactive Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 15 Mar 2016 Location: Bolton, MA Online Status: Offline Posts: 270	Posted: 13 Apr 2016 at 1:12pm
	Being an engineer myself, I hope they have a good laugh. It freaked me out, I was running the furnace off and on for a few days prepping the new pod. When the battery got low I ran over to plug into shore, suddenly the A/C fan kicks on - and I didn't know what to think. I had to do a bit of searching on the web to figure it all out. Dometic is coming out with an upgraded thermostat, with backlighting, but I have only seen brochures and they give little other specs, maybe that will function on a more user friendly level.

techntrek Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group - pHp Joined: 29 Jul 2009 Location: MD Online Status: Offline Posts: 9062	Posted: 15 Apr 2016 at 10:18pm
	IMO the older analog thermostat was better. An I'm saying that as a tech head.
	Doug ~ '10 171 (2009-2015) ~ 2008 Salem ~ Pod instruction manual

jato Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Feb 2012 Location: Kewadin, MI Online Status: Offline Posts: 3257	Posted: 16 Apr 2016 at 8:41am
	I like the analog on our 177. Simple and easy. And no problems.
	God's pod '11 model 177 '17 Ford F-150 4WD 3.5 Ecoboost Jim and Diane by beautiful Torch Lake "...and you will know the Truth and the Truth will set you free."

Retroactive Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 15 Mar 2016 Location: Bolton, MA Online Status: Offline Posts: 270	Posted: 16 Apr 2016 at 9:15am
	The one thing I don't like about this thermostat is the that the "swing" is too much. In my unit it has to drop 4F before the furnace kicks on, that got annoying when we slept in it for the first time last night. It wasn't too bad because it only got down to 40F outside last night, but the 4F swing woke me up a few times. I would prefer no more than a 2F swing. Most digital thermostats for homes allow a swing setting. It will be interesting to see if the new Dometic one will have the feature.