Heater AC problem -- or feature?

[Johnnyfry]

Greetings,
I have a new 318SAB and have had an issue with the furnace. After using the furnace for a few days I decided to reset the temp differential on the tstat to 1° instead of the 2° default. From that point on, whenever the tstat would call for heat and begin to turn on, there was a chatter (as from an electrical relay) from the ceiling mounted AC unit. After a few seconds the chatter would stop and the furnace would start. Has anyone had this problem? I eventually set it back to 2° and it quit, but I would like to have it set at 1°

Second, possibly related, issue. I experimented with the fan speed setting when using the AC unit. The low setting was best as it was lass noisy. When I had it set this way (LO) the AC blower (only, no cooling) would come on every time the furnace started. Somehow I think these issues are related. Dealer did not furnish a manual for the AC (Dometic, 15K BTU, no heat coil or heat pump feature).

Any help appreciated. My first post.

John Freitag

[Jim W]

John,
I too have a 318SAB, an have not notice this issue that you have mention. My unit has been in storage since late Oct and will not be out for another month, so I can not check my unit for you. We did run the heater when we were camping in Door County WI, and were happy with the set points on the thermostat.

I have found out in the past that if you set the temperature points to close together. The blower motor will cycle on an off to much thus causing the blower motor to over work. The furnace never knows when to shut off, it is cycling continuously when you only have a two degree differential between the set point on the thermostat. What we do is turn the blower motor on to run continuously like our house and then let the heat cycle on and off. This seems to save the blower motor from over working. Since the motor works the hardest and consumes the most electricity on initial start up.

I would also go on the Dometic site and see if you can down load a manual for your model.
Jim W.

[Johnnyfry]

Thank you for the advice Jim. I originally fiddled with it because the trailer seemed to cool down too much between heater cycles. Your idea of running the blower continuously should help that and I gill give it a try.

Thanks
John

[GaryAnnaW062378]

Is it normal that the AC unit also runs when the heater is on? Doesn't seem as cold when it's running when the heat is on tho. Or is this a recirculating feature to push the heat around?

[Halibutman214]

Is it normal that the AC unit also runs when the heater is on? Doesn't seem as cold when it's running when the heat is on tho. Or is this a recirculating feature to push the heat around?I made a post about this sometime back and yes this is normal. If you read your manual for the thermostat it talks a little about this. It's not the A/C per say that is actually running but rather the A/C fan. The compressor never kicks on. My question that I never did get an answer for is what actually causes the A/C fan to kick on as it doesn't do it all the time. I'm guessing when the thermostat senses a temp higher than it's set for. I had an electric heater running near the thermostat when the A/C fan kicked on. I think it's a great feature but something they should explain on a walk-thru. As far as the noise referred to.... that should not happen.

[mhs4771]

On some of the Keystone uniits, if the Fan is set to anything other than Auto, the fan will run when the furnace kicks on. Try setting the Fan to Auto and see if that stops the AC fan from coming on.

[Halibutman214]

On some of the Keystone uniits, if the Fan is set to anything other than Auto, the fan will run when the furnace kicks on. Try setting the Fan to Auto and see if that stops the AC fan from coming on.Actually (according to the manual) setting it on Au will enable the fan recirc feature.

[Ayotte]

We have a 2012 cougar x-lite 26 sab and I tried the 1 degree setting and the same thing happened to me. Did not seem that the furnace operated properly. Every time the thermostat called for heat a relay(in ac) would click and sometimes the furnace would not cut in. Changed it back to 2 degrees. Was going to ask dealer but forgot to.

[f6bits]

But doesn’t setting it to “ON” turn on the fan full time? Granted, I’ve replaced my with a digital, so maybe “ON” would only work if HEAT is off.

Actually (according to the manual) setting it on Au will enable the fan recirc feature.

[Halibutman214]

But doesn’t setting it to “ON” turn on the fan full time? Granted, I’ve replaced my with a digital, so maybe “ON” would only work if HEAT is off.Yes it turns on the furnace fan, but at some point on many of these, in addition to the furnace fan, the "A/C" fan kicks on and circulates the air thru the ducting.

[Halibutman214]

I suspect but can't say for sure that part of this clicking described when changing to 1 degree differential has to do with the fact the thermostat is sensing the ambient temp is more than 1 degree above that at which it is set at and therefore the only thing that is coming on is the A/C fan. This happened me my first time out and I was quite confused. I finally had to break out the dreaded manual.

[Camp I am]

JohnnyFry; the same thing just started with mine on our last trip. I set the differental to 1 degree and started noticing the AC clicking. I too suspect that if I turn it back to 2 degrees it will stop. At 2 degrees I did not notice the AC running at all to circulate, at 1 degree maybe its trying but I just get the clicking. Hopefull someone can shed more light on this for us. :party:

[jbcason]

Along these lines, is there a way to run furnace and heat strips in A/C at the same time? Thanks.

[CUFFS054]

Halibut, on mine switching to man fan energizes the A/C blower not the furnace.

[B&T]

JohnnyFry; the same thing just started with mine on our last trip. I set the differental to 1 degree and started noticing the AC clicking. I too suspect that if I turn it back to 2 degrees it will stop. At 2 degrees I did not notice the AC running at all to circulate, at 1 degree maybe its trying but I just get the clicking. Hopefull someone can shed more light on this for us. :party:

Back in December, I did the same, after searching this forum, found others here that had discovered the very same "FEATURE". the clicking was driving my DW nuts so I set it back to 2 degrees and had a more peaceful camping trip :)

[Cougar 28]

Mine did the same thing when I turned the heat on the AC fan came on dealer said the same thing that when in auto setting this will happen.