NO Filters

What damage can be done to a heat pump system by not using filters. I know the returns can collect dust, but how about damage to the air handler?

The dirt will build on on the blower wheel unevenly cause a bushing or bearing to fail prematurely.

Also clogging up the A/C coil causing ice to form and freeeze up.

Jim, not sure I follow the part about ice on the AC coils? Do you mean at the outside compressor? This system was partailly iced up but not sure how the dust inside impacts the outside componets. Sorry for my ignorance.

I think he is talking about the coils at the air handler. This is a costly fix.

Filters have little to no effect on the returns…

Blower “sux” from the returns, not “blows”.


Without enough air flow over the indoor coil in cooling mode on a heat pump, the system pressures and temperatures will drop below 32 degrees and cause frost and ice to form on the indoor coil and the suction line and compressor, more importantly cause the superheat to drop to a point that the compressor may try to slug lquid refrigerant. Remember your high school physics, you cannot compress a liquid.

This may be TMI, just remember that lack of indoor air flow is important and is a classic explanation of what you are seeing.

As for Jeffery saying that return has nothing to do with how a blower blows, think about it if the return air is blocked tell me how the blower gets air to blow?

That is not what I said.

The point I was making is that Scott inferred that if no filter was installed, the amount of dust collecting in the returns would increase, as if the blower sent the air in the direction of the returns. It does not. It pulls air from the returns, and blows it across the coils. Any dust at the blower would have to make it through the HVAC, through the supply distribution, through the open rooms, then finally back into the returns. The increase in dust in the returns would most likely be minimal, as compared to when a filter is installed.