410A Completed full maintenance on split two split system units Customer noted that the upstairs unit seems to not be cooling once it gets hot outside. It just won’t get the temperature and I’ll sit out like 80°. I checked the refrigerant levels for that unit and they were low. I performed a complementary leak search was unable to find anything and I went ahead and charge the unit back up and got the sub cooling and superheat level is good. The unit is now cooling and should have no issues. The customer might need a more intensive leak search here soon just to ensure there’s no leak or to find the leak. I checked all wiring and components Tested capacitors, capacitor on that same unit with the low refrigerant was also reading low. I replaced that for the customer. Tested fan and compressor amps Took temperature splits from supply and return Tested blower fan amp Tested float switches Flushed and vacuumed out condensate lines There was a lot of bio growth growing in the air handler