I installed a Daikin Inverter mini split with 2 heat pumps and 7 indoor air handlers. The system works great however the homeowner has been complaining of an exhaust/ urine smell from 2 of the units. It is an eickler home. I have talked to many people both from daikin and other suppliers and specialist and I have pretty much checked of all of what they told me to look for- not draining correctly ( it is draining good)
- refridgerant leak ( not leaking)
- odor in room ( it is a cleaned daily).

The strangest thing is that the homeowner says that the unit only smells at the hottest point of the day when the unit has to work at it's hardest .

I have a daikin rep out to look at it but he says he has never heard of this problem.

Has anyone every had this issue before of have any ideas what it could be? Also I just cleaned the unit in question and it made no difference.