A/C fan runs with furnace

myclmac · 11-18-2015, 03:17 AM

New to the forum and like the fact there is a MBS section. Wondering if anyone has experienced this problem? Getting ready to head out to the CA coast for a few days and fired up the furnace for the first time on our new 2401R. We are plugged in at home and when I fired up the furnace with the thermostat the furnace fired up and produced heat but the A/C came on as well in the fan mode. Does not make a difference what temp the thermostat is set. When unplugged from shore power the furnace works fine. Any suggestions would be appreciated.

Mikegjax · 11-18-2015, 06:40 AM

Quote:

Originally Posted by myclmac

New to the forum and like the fact there is a MBS section. Wondering if anyone has experienced this problem? Getting ready to head out to the CA coast for a few days and fired up the furnace for the first time on our new 2401R. We are plugged in at home and when I fired up the furnace with the thermostat the furnace fired up and produced heat but the A/C came on as well in the fan mode. Does not make a difference what temp the thermostat is set. When unplugged from shore power the furnace works fine. Any suggestions would be appreciated.

Check you fan setting and ensure it is set to "auto".

BTW, welcome and enjoy!!!

**wmtire** · 11-18-2015, 06:53 AM

Quote:

Originally Posted by Mikegjax

Check you fan setting and ensure it is set to "auto".

X2, this is a common question with the digital thermostats. You have to have the fan set to auto as Mike stated.

The reason the air conditioner isn't coming on when you are not hooked to shore power, is it ONLY works off a form of 120 volt AC power, whereas the furnace works off of 12 volt DC power and thus operates either from the converter if connected to shore power, or the battery if not.

It's going to be just as simple as setting the fan in the thermostat to the auto mode.

These threads may help

http://www.forestriverforums.com/for...elp-46919.html

http://www.forestriverforums.com/for...tat-48588.html

http://www.forestriverforums.com/for...-on-94302.html

I am also going to move this question and answers over into the Forester section.

**wmtire** · 11-18-2015, 07:23 AM

I forgot to add in my previous post, welcome to the forums. Please fee free to ask about any questions or concerns you may have. The members here are very knowledgeable and can help with about anything you may encounter.

Not knowing your RV experience, I always usually point out a few other articles to peruse at your leisure, that help in the understanding of your RV's electrical:

Basic RV Electricity - RV Information (RV Maintenance)

RV Converters and Amp Draw - RV Information (RV Maintenance)

MNtraveler · 11-18-2015, 09:00 AM

OP said he was plugged in at home and the a/c DID come on with the furnace.

Questions: did you hear/feel the a/c compressor running in the ceiling or just feel cold air blowing out of the vents? Did the cold air come out of the floor vents or the ceiling vents?

Land of 10,000 Lakes
2016 Forester MBS 2401R

5picker · 11-18-2015, 09:09 AM

Quote:

Originally Posted by MNtraveler

OP said he was plugged in at home and the a/c DID come on with the furnace.

Nope... he said the A/C came on in the fan mode...

MNtraveler · 11-18-2015, 09:54 AM

Yup, he said "when I fired up the furnace with the thermostat the furnace fired up and produced heat but the A/C came on as well in the fan mode". #3 said the reason the A/C DIDN'T come on, which he said it did, is because he WASN'T plugged in, which he said he was. So I was responding to that.

My questions are intended to help the OP sort out exactly what is happening. Let's focus on that.

Land of 10,000 Lakes
2016 Forester MBS 2401R

**wmtire** · 11-18-2015, 10:03 AM

Quote:

Originally Posted by MNtraveler

Yup, he said "when I fired up the furnace with the thermostat the furnace fired up and produced heat but the A/C came on as well in the fan mode". #3 said the reason the A/C DIDN'T come on, which he said it did, is because he WASN'T plugged in, which he said he was. So I was responding to that.

My questions are intended to help the OP sort out exactly what is happening. Let's focus on that.

Land of 10,000 Lakes
2016 Forester MBS 2401R

MNtraveler, it seems you are now responding to my post. I explained to the member why the air conditioner fan wasn't coming on, when he wasn't on a form of shore power, as was stated in their post (in red below) as opposed to when it was while connected to a form of shore power.

Quote:

Originally Posted by myclmac

New to the forum and like the fact there is a MBS section. Wondering if anyone has experienced this problem? Getting ready to head out to the CA coast for a few days and fired up the furnace for the first time on our new 2401R. We are plugged in at home and when I fired up the furnace with the thermostat the furnace fired up and produced heat but the A/C came on as well in the fan mode. Does not make a difference what temp the thermostat is set. When unplugged from shore power the furnace works fine. Any suggestions would be appreciated.

Quote:

Originally Posted by wmtire

X2, this is a common question with the digital thermostats. You have to have the fan set to auto as Mike stated.

The reason the air conditioner isn't coming on when you are not hooked to shore power, is it ONLY works off a form of 120 volt AC power, whereas the furnace works off of 12 volt DC power and thus operates either from the converter if connected to shore power, or the battery if not.

It's going to be just as simple as setting the fan in the thermostat to the auto mode.

MNtraveler · 11-18-2015, 10:23 AM

OK, and I was responding to the part where OP said he was plugged in and after turning on the furnace the A/C also ran (in fan mode - which could mean two things) (and the A/C actually might or might not have been coming on). But clearly there are too many voices here so I'll drop off and let you and others here assist the OP. Thanks.

Land of 10,000 Lakes
2016 Forester MBS 2401R

l1parker · 11-18-2015, 12:53 PM

We went out and stayed at a RV park for the first time recently. We mostly do dry camping. We have a 2014 221RBXL. Same thing happened. Our thermostat has 3 states, ac, fan, furnace and a separate button for on/off. The trailer has ducted ac (don't know if that matters). I couldn't figure out how to get the furnace only to come on. The ac doesn't appear to be active, only the fan. Eventually I gave up and simply unplugged the connector on the right side of the ac control box (under the filter on the ceiling intake). That stopped the ac fan, but still leaves the other ac appliances on. When I need the ac, I'll plug it back in. I tried the circuit breaker that has "ac" written next to it, but it shuts off all the ac sockets, etc., as well. Crude but effective works for me.

**wmtire** · 11-18-2015, 12:58 PM

We have many of the operating manuals for the thermostats in our library here on FRF. Since FR puts different brands and models of thermostats in their many lines if RV's it would greatly help if the members could post specifically which thermostat they have, and we can probably get you lined out correctly.

myclmac · 11-18-2015, 12:59 PM

Thank you everyone for the responses. The fan thermostat, as Mike said, needs to be set to AUTO. That did the trick and the furnace now runs with heat without the A/C fan on while on shore power. Operator error on my part because I was not pushing the +/- control to the side only up and down. We are good to go!! Until next time.

SilverArrowPro · 11-18-2015, 03:34 PM

I purposely keep my fan on with the heat, as it provides white noise so you don't hear the furnace as much, and it helps to keep my sinuses from drying out. I actually had to ask how to do it, so the above auto vs manual is exactly what the dealership told me.

Ham Camper · 11-18-2015, 04:33 PM

I will add my 2 cents. When I tried to use my furnace the first time the blower on the roof air conditioner would also kick on. My air is ducted in the ceiling. No where close to the furnace ducting in the floor. A quick call to the dealer and it was solved as others have mentioned above. Turn your thermostat fan setting to auto. Now your air conditioner should not run. Just the furnace. I scoured the manual for my rig and nary one word of this. Pretty bad instructions if you ask me.

TURBS · 11-18-2015, 05:00 PM

Quote:

Originally Posted by SilverArrowPro

I purposely keep my fan on with the heat, as it provides white noise so you don't hear the furnace as much, and it helps to keep my sinuses from drying out. I actually had to ask how to do it, so the above auto vs manual is exactly what the dealership told me.

Like you we always have the a/c fan on when furnace is on.

5picker · 11-18-2015, 07:00 PM

I currently have just the analog thermostat but like TURBS & SilverArrow, (and unlike many others who posted here) I would like the option of the A/C fan running with the furnace.

Heat rises and having the A/C fan running would even out the temperatures throughout the unit much more effectively than what just the furnace is able to do.

If I upgraded to the digital thermostat, would I have that option or is there something in the A/C unit that had to also come that way from factory?

I was thinking of this stat...

dicky1243 · 11-18-2015, 08:40 PM

Quote:

Originally Posted by myclmac

New to the forum and like the fact there is a MBS section. Wondering if anyone has experienced this problem? Getting ready to head out to the CA coast for a few days and fired up the furnace for the first time on our new 2401R. We are plugged in at home and when I fired up the furnace with the thermostat the furnace fired up and produced heat but the A/C came on as well in the fan mode. Does not make a difference what temp the thermostat is set. When unplugged from shore power the furnace works fine. Any suggestions would be appreciated.

Set thermostat to AUTO

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