I have a question regarding a couple of dehumidifiers that I installed in my in-laws basement, circa 8/2011. They are fad704dud frigidaire 70 pint/day units hooked up to drains so no bucket emptying is usually needed. All three were running for a long time on initial hookup to dry out the basement, controlled it.
This year one unit kept running but produced no condensate, I diagnosed it as sealed system failure and the company was nice enough to offer a refund on the purchase price.
The two remaining units are producing condensate but also ice up almost immediately on startup. I am scratching my head re: this behavior given that it's about 65-70*F in the basement and the humidity is only 65-70%. In other words, these units shouldn't be featuring a evaporator HX that is half clogged (growing from the bottom to halfway vertical on HX) with condensate after just 1/2 hour runtime.
The replacement unit I bought (FAD704DWD) has a noticeably higher discharge temperature and almost no condensate frosting, even after a full day of non-stop running under similar conditions. The two older units ice up so badly that the condensate buckets fill over time from ice forming on the bottom of the drain pan (above the bucket) and dripping down.
So here is my question: Do you think that the remaining two units may be on the verge of suffering from a sealed system failure also? That is, is the system so starved for refrigerant that the evaporator is cooling too effectively, leading to instant ice formation?
I have put the two remaining units on interval timers to limit ice growth but am thinking that may not be sufficient a band-aid. If 1/2 of the HX turns into a ice block within 1/2 hr of operation while in a warm basement with relatively benign humidity levels, something is off... Any insights are appreciated. Thanks!