I noticed that cold air was rushing out of the seam near my AC evaporator, so I added foil tape around the seam (see photo). Is that appropriate, or does that minor leakage serve a purpose? The rest of the unit's seams are taped, so I don't know if this was an oversight or intentional.
I usually pack the holes with a sealing clay we call monkey sh!t. Sorry I don’t know the proper name, if the air handler is inside the home some leakage is not as big of an issue. Having the air handler properly sealed will increase the system efficiency, on older homes that space was not conditioned because it all went up the vents or with gas appliances that was the case.