AC Fan (?) Cycles Constantly

rrcbov

I took delivery of a new Tab 400 BD earlier this week.  My AC cycles constantly - it will run for less than a minute, shut off of just a second or so and then repeat.   I think it’s the fan as I hear constant humming even while the fan isn’t running.

I sent a note to NuCamp on this but it’s Saturday so I thought I’d try the knowledge base here.

ChrisFix

@rrcbov
My June 2020 delivery 2021 T@B 400 does exactly the same thing. I haven't decided if this is normal operation or if something is off. 
I used to run it with the Fan setting on "Low" or "High", which keeps the fan running 24/7. It wasn't until the last couple of months that I set it to "Auto", and have observed the same phenomenon as you. The camper stays cool, and seems to quickly get to it's set point, so I haven't given it too much thought as of yet, but as I'm coming up on my 1 year warranty, I do want to make sure there isn't a problem.

Denny16

Try making sure the dinette area AC vent it turned away from the door, where the thermostat is.  This fixed the short cycle issue for us.
cheers

rhyno

Edited to clarify...
Our 2021 400 runs constantly until it hits temp, then cycles frequently to maintain temp. We too run the fan all the time to mask the frequent compressor starts/stops. Vents are not pointed toward t-stat.
Following to see if this is a problem needing fixing but figured it is just due to the big AC cooling such a tiny space, it doesn't need to work more than a few minutes at a time to maintain the set temperature once it reaches it. 

rrcbov

Sounds like I’m not alone. My dinette vents have been directed downward.

I will post the reply I get from NuCamp.   I also posed the same question to Dometic. 

rhyno

@rrcbov and @ChrisFix are your fans turning on and off before hitting set point? If so that sounds like a different problem from mine. 

rrcbov

I’m finding that I need to run my ceiling fan to exhaust hot air - there is a 25 degree temperature difference between the floor and ceiling of the camper here in the mid-day South Florida direct sunlight.   

The location of the thermostat doesn’t seem to be optimal.  I’ll have to search for ideas on this project.

ChrisFix

rhyno said:

@rrcbov and @ChrisFix are your fans turning on and off before hitting set point? If so that sounds like a different problem from mine. 

I think both, but I haven't paid close enough attention to it. I will next week when I'm spending a week in south Florida. 

rrcbov

Here’s what Dometic says

Denny16

Yes, I remember reading something about this before.  I have high frequency hearing loss, so the fan cycling does not bother me, but I can hear the compressor come on when it starts up.  We normally turn the CoolCat off at night when sleeping.  I do not hear the Alde running either, so we leave it in at night when it is cool out.  Thanks for posting this.
cheers

ChrisFix

@rrcbov
Thanks for posting that. It exactly describes how my unit is working...which is great, since it means all is well!!