https://www.youtube.com/watch?v=LJb6oE7NH30&t=2s&ab_channel=HVACXSUPPLY
A. How to check the drain pan conditions?
1. Get a video camera tube sensor, insert into the furnace through Hi-
limit sensor hole, checking above the first heat exchanger to see the
coil drain pan’s condition.
2. Disconnect the condensing water hose and the adapter, Open all
screws on the coil front cover, then remove the two pieces cover
metal away to both side, look at the bottom when you remove the two
pieces of cover, you will see a piece of metal bar which fixed by four
screws on side , this bar would be functioning of support the front of
coil. After you remove this bar, then you have enough gap to check
the bottom of inside of coil with that camera.
B. How to replace the coil drain pan?
1. Pumpdown refrigerant of the system first, open outdoor unit cover, hook
up pressure gauge to suction port, fully turn off the liquid port shut off valve
, and turn off suction port valve in half or more, press SW1 for 5”, untill
LED blinking, then press SWI until 08, then press SW2 for starting pumping
down. When it is processing, monitoring the suction port pressure, fully turn
off the suction line valve when the pressure is going to 0, and also you
would get a error code of E3 . You have completed the pumpdown
procedures. Then disconnect power of 240v from service box.
2. Disconnect two flaring connections from indoor cased coil, try remove
bit for enough space to pull out the coil from the case. unscrews all on the
case cover, also you need to remove the support metal strip on right, and
two screws which are fixed the side drain pan on left top outside, remove
the support L-shaped sheet, then you can try to move the coil out of the
case.
3. Remove two screws on the pan which fixed with coil on both side, then
you will get a naked copper coil .
4. Replace with the new black plastic drain pan, get rid of the spare side
drain pan and L-shaped support, if you are installing in vertical. Next you
need slide the coil with new drain pan into the case, remember that metal
pan at the bottom of coil still attached. getting all cover screws back on,
and reconnecting the flaring with two copper line set. Please note, when
you reconnecting the flaring, apply some Nylog for good sealing would be
very necessary.
5. Repeat as a new installation to pressure test and vaccum system as
required, then release refrigerant from compressor. Done