Heat pump noises

[subfan1]

Hi we have a 2019 23CB and are using the heat pump at night. We have 30 amp service, the temperatures at night are in the low 40s . When it starts there is a long hum , about 35 to 45 seconds then the system starts to blow air. Normal?
Then when on, there sounds like door flaps are shutting shut. Pretty loud
Took it in to our dealership, could not duplicate. Any ideas?

[LuckyCloud]

Door flaps... multiple locations? There’s a range hood vent cover on the outside that might be exhausting some air?

I’d be surprised if the heat pump is effective in the low 40’s.

[LuckyCloud]

Would you be able to record the noise and present the recording to the dealer? Like a video with a phone...

[majorairhead]

That first sound you describe I would think is normal, the door flap sound is unfamiliar to me though. Our heat pumps go through differing cycles, including defrost cycles, and make some differing sounds as a result. No slapping or slamming of doors for us though

[kpm]

Originally Posted by LuckyCloud

[...]There’s a range hood vent cover on the outside that might be exhausting some air?[...]

We hear this sound too.

[subfan1]

[QUOTE=LuckyCloud;2196624]Door flaps... multiple locations? There’s a range hood vent cover on the outside that might be exhausting some air?

I thought the range hood door flap was a stretch but I still had to rule it out. I locked it in place and turned the heat pump on and the noise is still there.
Thanks for the tip, trying to rule things out.

[bwoodtx]

The hum on start up is normal.

The other noise is when it goes in and out of defrost. It is the switching valve. If you don't want to hear this, supplement your heat pump with a small ceramic heater. HP won't go in and out of defrost as much.