Should be on the supply side but if you have no heater, just an air handler, as long as its moving the air , its ok--Wet are off the coil will rust a heat exchanger--

 

Before the blower as in the return side or supply side? With furnaces the evaporator coil on the supply side after the heat exchanger to prevent the heat exchanger from sweating and rusting out. On heat pumps and straight air conditioners with air handler the coil is generally in the return although it can be on the supply side of the blower as long as any electric heating elements are on the supply side of the coil.

 

this is on the return side so it is "drawing" air through the coil rather than "pushing" air through the coil. generally at least in CT air is pushed through the coil on straight a/c systems. I have heard if it was a a/c furnace that yes you would want this for the same reason you just stated with the heat exchanger. but this is just a/c which is why I was confused.

 

It should be fine so long as it is moving the required air

 

while at this job I did notice a ton of water issues which I was thinking this could be why. I was not there to pyshcally test any other aspects of the system. this system was 6months old and already had mold growing in the supply side. I told the customer to contact who ever installed the system.

 

Was there a ptrap on the drain. It has to have one to drain properly if the coil is on the negative side of the blower.

 

there was a Ptrap Which was slightly clogged so I blew it out.

 

Hopefully the Vent was After the trap, if before then the unit will not drain until the fan shuts off as the water level has to overcome the static of the fan

 

Common through out most of the country for the coil to be before the blower on an air handler.

 

I have seen gas furnace dual fuel arrangements where the coil was on the return. Bad for heat exchanger. It sweats from humidity

 

Mobile home?

 

I always see them on the return side unless it's a case coil on a furnace. That's why you need a condensate trap because the negative pressure from the fan pulls air in not allowing it to drain without one. And case coils don't need a trap cause the positive pressure doesn't prevent it from draining.

 

Trane RTU have coil before HX and they do rust.

 

A p trap is required for positive press and negative press units. The air pushes the water out of the way, backing up the water in the drain pan and overflowing