Heat Pump Problem

[dr.perry]

I have a 2015 Dutch Star 4018. I keep it in an insulated shed and set the thermostat to 58 degrees. When checking a couple days ago, I noticed that the rear heat pump did not seem to be working. When the thermostat is set above the inside temperature, the heat pump starts humming like it's going to kick on...and then stops. It repeats this behavior but never kicks on. Any ideas on what's going on?

[Capt. Bill]

What is the amperage of the shore power you're plugged into? Does your other units heat pump work ok?


Happy Trails

[Newmar2856]

What is the air temperature inside your building? I don’t recall the exact temperature, but if you’re in the low 40’s the heat pump won’t turn on as it’s too cold.

[dr.perry]

Capt. Bill - The shed has a 50 amp circuit. The front unit works fine. I tried turning the front unit off - no difference, the humming sound from the rear unit, then nothing.

Newmar 2856 - The temp inside the shed is mid-50s.

[Ken C]

I had a similar issue with our front AC. I could hear the compressor kick on, but no fan due to a failed start capacitor. YouTube has videos on how to test the capacitor. Another option is to remove the front capacitor and install it in the rear unit and see if it will run.

[Ricci]

Hi - Sounds just like a capacitor. Buy a kit and replace them.


Tom

[Bushy]

I'm guessing that your coach is all-electric with an Oasis hydronic heat system - in addition to your heat pumps. I live in a northern climate - too cold to get much use out of the heat pumps. In our twenty years of RVing, we have used the heat pumps maybe three times. We find them to be noisy with a very limited effective operational temperature range. Compared to the regular Oasis furnace, the heat pumps just don't make much sense in our climate. We DO USE them for cooling in the summer. If my front heat pump did not work I would take a big yawn. To each their own.

Can you use your Oasis system set on AC (electric heat elements) and use that instead of the heat pumps?

[dr.perry]

Thanks to everyone for the replies. I'm going to get on the roof and do some basic troubleshooting. It sounds like it could be a capacitor and I'll get some help with that so I don't do something stupid. :-)

[C.Martin]

Originally Posted by dr.perry

Thanks to everyone for the replies. I'm going to get on the roof and do some basic troubleshooting. It sounds like it could be a capacitor and I'll get some help with that so I don't do something stupid. :-)

It helps to have a clampmeter with capacitance test feature. My rear unit fan capacitor went bad and did what you described...in air conditioning mode (Jan in Florida...still using A/C)

I would try in air conditioning mode...Just to rule out a reversing valve issue...

Up on the roof...four Phillips head screws remove the cover. The dual start run capacitor can be tricky to find with the same uF values....so, might take a picture of yours to make sure you get the right one. If it is the fan start capacitor...if you have someone to help. ...have them turn the unit on. While you listen for the humming, or notice the fan cage bump. Carefully give the fan a spin with your hand...and see if it doesn't start running. If it does...it's probably just the fan start capacitor...if it doesn't might need a new fan motor.

I keep a spare capacitor with us now. It's an easy repair...but only if you have the part. Seems these things always break on a Sunday, or when nobody within 100 miles has stock of the part.

There are a few different models, so yours may use different values than mine.

[dr.perry]

Thank you, Charlie. I'll give that a try.

[Pine Stump]

Normal when too cold for the unit mine does it all the time in spring and fall before full winter storage shut-down.
It does that so that when the water freezes when below 32° it will not ruin the unit.

[hohenwald48]

Are you sure it's not just the heat pump defrost cycle running? The defrost cycle runs the compressor without the fan.