Air conditioner causing audible clicks/pops in speakers; how to fix?

[zinkzinkerson]

Problem:
When the air conditioner unit turns on and when it turns off, if the A/V receiver is on, the front and rear speakers emit a brief but audible click/pop.

Background:

• I live in a rented condo (i.e., assume I cannot do electrical work on the unit).
• The furnace room is situated in one corner of the living room and houses a combo A/C + furnace unit.
• The A/V centre is approx. 5 feet from the wall that surrounds the furnace room.
• The subwoofer is located immediately adjacent to the shared wall with the furnace room.
• The speaker wire that feeds the rear speaker channels runs along the shared wall with the furnace room. The maximum one-way length of the wire run to the farthest rear speaker is approximately 30-35 feet.
• The A/C unit is on its own electrical circuit (i.e., not shared with any other circuit at the breaker panel); let's call this Circuit 2.
• A separate circuit feeds a duplex wall receptacle which services the living room. Let's call this Circuit 1.
• The duplex receptacle on Circuit 1 feeds two brand-new surge protectors: a Tripp-Lite Isobar 8 Ultra and a GE UltraPro Model 14096.
• The Tripp-Lite Isobar unit feeds the home theatre equipment (Denon AVR-S900W; Sony X95K; XBOX Series X; Panasonic UB-820; Roku Ultra; and Paradigm subwoofer)
• The GE UltraPro unit feeds various home networking equipment (e.g., wifi router, NAS, etc).

I've attached a schematic of the general layout of the system below. Note how the subwoofer (and associate cable) + speaker wire feeding the rear channels are in close proximity to the furnace room wall (and therefore the A/C unit).

Efforts to date:
Previous research seemed to indicate the source of the audible clicks/pops could be the A/C compressor turning on/off, with the root cause being EMI/RFI being generated by the compressor motor feeding into the home theatre system somewhere in the chain (see this thread).

To that end, I purchased the Tripp-Lite Isobar surge protector unit noted above specifically because it was marketed as having excellent EMI/RFI filtering (see product page). However, after testing with both the old surge protector that came before and the new Isobar, there has been no apparent difference in the outcome - the audible clicks/pops remain when the A/C unit turns on and when it turns off.

Assistance requested:
If the cause is indeed EMI/RFI, is this a matter of the Isobar not providing enough EMI/RFI filtering?
Or is the problem likely stemming from a different avenue?

What can be done to further diagnose the issue and identify a potential resolution?

Thanks!

 

[sam_adams]

Probably what is happening is arcing of the relay contacts for the motor for the HVAC unit. Normally this would be dealt with using a RC snubber across the contacts. Since you state that electrical work on the HVAC unit is out of the question, there is little that you can do to mitigate this with OTS products since the EMI/RFI is being transmitted through the air and not the wiring—although that could be a remote possibility.

Some explanation here.

 

[Hayabusa]

Where are you located? Sometime swapping AC phase (rotate the plug) can help you out?

 

[Hayabusa]

I assume the click is only there when the Denon is powered on?
Is there a difference what source is driving the Denon?

 

[DWPress]

Some sort of EMI/RFI shield on the wall inside the closet? Worth a google....

 

[AnalogSteph]

I reckon there's a ground loop going straight through the AVR that shares an internal path with audio ground in there. Does unplugging the subwoofer audio cable make any difference?