Switching back to spun fiberglass hvac filters?

[Marian Smith]

I had an outdoor unit “freeze up” on a tenant. Hvac guy says the unit read fine so no freon needed, etc. Filter had been changed a few weeks earlier and was clean enough but supposedly restricted air flow can cause the problem...guy said to wait 4 hours and turn system back on if it happened again. He did clean the indoor coils and said that should improve performance by 20%. I looked at hvac-talk and there seems to be quite a number of site people who say fiberglass filters keep the coils clean enough and the pleated put a lot of stress on systems not designed for them, especially in ac season. The filters I ordered were called “ez flow” which says something. I have all R22 units. The one that froze up has the original furnace and coil from 1985.

[Jim K.]

@Marian Smith

I would look less at pleated versus spun fiberglass and more at the MERV ratings of these filters. Most people do not need something like a MERV 13 filter in their units. They'd do perfectly fine with a MERV 4 filter. But they buy the higher-rated filter, thinking they'll get noticeably better performance. The higher the rating, the more restrictive the flow, the more likely something like this cooling issue would happen.