Noisy ac

[GlennWest]

Our living room ac makes a rumbling noise. It's worse in heat pump mode but also rumbling in ac mode. I took the cover off to check out. It is free of debris. There is movement back and forth, horizontally, in shaft, no side to side movement. Rear ac is relatively quiet and same play is in it's shaft. Any suggestions?

[keithandpenne]

A couple of things come to mind, loose mounts or compressor working hard due to high load from dirty coils.

Is this something new or has it always been loud? Is it a metallic noise or just a vibration type sound? If metallic, it could be internal in the compressor, if a vibration, it may be a loose mount to the roof or duct.

I haven't been in ours so not sure what access is available to the coils but if they are dirty or restricted it will make the compressor head pressure go up. Also, running the fan on high speed in hot weather will reduce the load the compressor pressures.

Dust, pollen's and other airborne seeds can collect on the condenser and dust that passes your filters can clog the evaporator. Both can be cleaned with chemical cleaners but you would probably have to remove the unit from roof to do it.

Also, you can check your ducts with a mirror to make sure they have not been squeezed together by the ceiling insulation and causing airflow restrictions.

[RGordon]

My friends travel trailer a/c unit developed a loud rumbling noise and dirt daubers had got inside the squirrel cage fan on the enclosed part of the fan and built mud nest causing vibration. If it had been there since new, I would look inside the cover for shipping blocks that would prevent compressor movement during shipping. Some end to end movement of motor shaft is normal as long as it is mimumim.

[rverdlm]

The fan motor is mounted through 4 rubber gromets. My guess (happened to me) is that one or more of these gromets is bad. You should also check both squirel cages because just a little dirt will make them out of balance and that is what causes the grommets to go bad. Also don't wait to long to fix it or you will wear the hole in the metal bracket that holds the grommets and then you will need to replace that also. I went down this road 2 years ago with my bedroom a/c and this fixed it, so far so good!