Here's a NCBI write up on the dust mite allergens in the aircon FCU.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4443215/
So confirm got allergens one, and these would present a constant low source of contamination (in which pax in this thread are trying to fix with a good enough CADR with APs). And trust me there are much more hidden in the insides of the FCU, with conditions just nice for dust mites.
The concentration of Der f1 & Der p1 in air was higher after the air-conditioners starting one hours later, and the difference was significant (P<0.05, respectively). Additionally, dot-ELISA findings revealed that the allergen extracted from the dust was capable of reacting with IgE from the sera of asthma mice allergic to dust mites. The study concludes that air-conditioner filters can enrich dust mites major group allergen, and the allergens can induce asthma. The air-conditioner filters shall be cleaned or replaced regularly to prevent or reduce accumulation of the dust mites and its allergens.
I don't think it is merely the aircon filters. The innards are all messed up and it also consists of mold, which is also another very possible allergen for rhinitis, allergic cough and asthma.
So, 2 possible sources of allergens here. Dust mite droppings and then mold and its spores.
Actually in the aircon FCU, a large % is actually mold and not dust or skin flakes or what (which would hold dust mites/its droppings).
For me over the past few years I DIY cleaned my aircons and what i can only offer you is anecdotal evidence.
Other than my own experience, i have also been helping some pax around my neighbourhood to clean their units (esp after ** time in Phase 2 where there was a great lack of manpower for aircon services).
Some of these pax (they spread via word of mouth recommendation as they have relatives living ard the neighbourhood as well) have returned to ask me to clean again simply coz they noticed a difference in their allergies.
So far I have helped clean the aircons for abt a dozen houses ard my neighbourhood, so while that's not a lot of egs for anecdotal evidence, but i still think it lends to the trend that it is a major factor coz the customers did say they did notice an improvement coz during the washing i do chat with the fellas a fair bit and share the tips, including my own house + my parents (my father also has allergic rhinitis).
Allergic rhinitis actually is pretty pervalent in SG, around 40-50% of the population? Just to varying degrees only and whether it poses enough of a discomfort to everyday activities nia. (cant always take antihistamines on a near daily basis also, withdrawal issues etc).
You can read it here.
Pls do not PM me, not doing aircon cleaning services, coz i only do around my neighbourhood to help out....basically wu hua for me coz i'd just walk over and do, not transportation/time overheads.
You can also achieve the same effect with a chemical wash once every 1.5-2 months, probably if you have a very dirty FCU you'd need to do a chemical overhaul first.
Issue is that (1)
Chemical wash is ard $80 per unit and chemical overhaul is ard $150 per unit, more units will have discounts
and (2)
The aircon techs are using alkaline coil cleaners for these cleanings, hence the term "chemical". It is basically an alkaline (eg sodium/potassium hydroxide) + some surfactants. You cannot be using this on a regular basis coz the alkaline "dissolves" some of aluminum on the evaporator coil every time you clean, which means wearing down the coil and lessening its useful life (problems include corroded fins and gas leaks of the refrigerant pipes).
Some AC techs do have evaporator coil safe cleaners (non alkaline) and these are ok, small problem is that they are not as powerful in cleaning effect for the soil loads involved, hence you'd need a higher cleaning frequency.
DIY aircon thread
https://forums.hardwarezone.com.sg/...diy-clean-your-aircon-blower.5091470/page-279
Or maybe i am OCD paranoid with 1.5-2 mths wash. Perhaps you can fix the issue with just 6 months chemical wash, not sure, but i have my doubts due to my experience there, probably 3 mths is a good compromise. I also clean at my parents' place coz my kids stay there during most of the weekdays.
So it's gonna cost if we use pros, in fact annual expenses is > 1k for both places for the $80 chemical wash/FCU.
There are cons involved though - there is a learning curve involved in DIY, need to spend a bit on the equipment needed, and need to be careful as there is a small risk of screwing up the system like the electronics, the sensors (what the folks do in the thread do is a permanent plastic wrapping of the IR sensors, electronics bay at the RHS, and for the fan motor protection actually some of us do not even remove the blower so there is a sort of physical barrier protection).
BTW the cleaning is not this type of general service cleaning. It's much more thorough. (ps actually some steps dont even need to do if the cleaning is frequent, eg the vacuuming of the drainage pipe, simple coz there is nothing to clean over there if your maintainence is good).
). Luckily for my kids they seem to be outgrowing the allergic cough portion after they went into pri sch. Asthma is a bit of a different animal and may or may not be tied to this......no experience.
