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bduemig · 06-06-2021, 08:53 AM

Question. Does a heat pump vibrate more than a traditional roof air conditioner?

Ours seems to vibrate the roof, especially when the fan switches to high.

wolfe10 · 06-06-2021, 08:59 AM

Can't answer your question directly, but has it always done that or is this something new?

If a new vibration, remove the A/C cover (roof access) and check for a mud dubber nest on the fan blades that may be throwing it out of balance.

Also check the fan mounts.

bduemig · 06-06-2021, 09:17 AM

The motor home is new to us in defender, so it had always done it. The dealer changed the cover so I am assuming they would have looked. But that may be giving then too much credit.

Xmcdog · 06-06-2021, 09:25 AM

Likely the fan cage is bent or a mouse, wasp or something has built a nest in it.

Just remove the cover and check.

bduemig · 06-06-2021, 03:05 PM

Thank you for the comments

rvbiker45 · 06-06-2021, 05:17 PM

Sometime the vibration can be caused by the mounts that are holding the heat pump in place on the roof. There are usually 4-bolts that are mounted. They have, usually, foam rubber blocks about 1" thick that act as a seal and buffer that the heat pump/air conditioner will sit on. It is very common to see those mounting bolts torqued too tight and compressing the foam blocks more than they should be. The recommended compression is about 1/2". The torque value is 46 "/#. (going from memory) That is 46-inch pounds and that is not much. If the torque is more than that and the foam is compressed more than required, you could expect to have more vibration in the MH.

bddadles · 06-07-2021, 05:50 AM

Just to add to the fan and mud dauber responses. There are actually 2 fan blades in the A/C (at least on my Mach). When you remove the cover you only see the outside fan blade. There is actually a squirrel cage type fan blade inside the unit. It is on the other end of the motor shaft. It is more work to get to. I just replaced mine because the plastic that holds the mounting clamp was broken.It wobbled a bit and caused noise. Just a possibility.
As to your original question. We never know any difference between the A/C running or the heat pump running.

Something I would try is remove the cover and while you are on the roof have someone else turn the unit on so you can watch it run. That might tell you something.

One more thing to check out. This will seem unlikely but it just happened to me. I had a noise in the heat pump and I thought I had it traced down to the motor failing. I replaced the motor and when I opened the panel to hook up the motor wires the capacitors were bad. I have no idea why it was even running but the start capacitor has a small box attached to it (It is shaped like a postage stamp but much larger) and it was melted apart with just the internals holding the connection together. I'm making the assumption that the noise we could hear was arcing between the pieces.

hypoxia · 06-09-2021, 05:41 AM

Quote:

Originally Posted by bddadles

I replaced the motor and when I opened the panel to hook up the motor wires the capacitors were bad. I have no idea why it was even running but the start capacitor has a small box attached to it (It is shaped like a postage stamp but much larger) and it was melted apart with just the internals holding the connection together. I'm making the assumption that the noise we could hear was arcing between the pieces.

PTCR http://www.tiffinrvnetwork.com/crusingator/P/P-090.pdf