Greg

Well I finally had enough of this hot weather and lousy AC in the house so I figured I would check the air coil to see if it was dirty. Having pulled the cover off it was clean but I believe the A-coil is installed backwards (this is a newer house) I have a 3 ton Lennox with the air handler in the attic , the handler installed horizontally. Anyway the air flow is like this ......
air flow-------------> < A-coil like this(closed end getting air pushed through it
shouldn't it be
air flow ------------------> >coil(open "/\" end recieving the air flow

HVAC Doc

Depending on the model number, a couple of coils can be mounted that direction. Also not uncommon when you have a Carrier/Bryant or Rheem/Ruud/Weatherking with a N coil as one part of the N would be pointed into the airflow. What does your air filter look like? Did you check the other side of the "A" to make sure it was clean? Sometimes those arrows can be deceiving as well when a cabinet is flipped one direction or another. What is the temperature drop across the coil (air into coil vs. temp of air out)?

CynicX

easy way to tell with a lennox coil is the drain pan....although horizontal you can install it backward, vertical cant obviously because of the drainpan....on a horizontal lennox there will be four sets of drains....2 on the bottom 1 is reg drain 1 is emergency drain....and 2 on the side for horizontal mounting like yours.....in your case i'm assuming you have a horizontal gas furnace with the coil after it.....the drain pan thats not being used (the vertical one) should be toward the furnace not the duct work.....if the coil is before the unit for some reason then the unused drain should be toward the ductwork....this way you'll know if the coil is facing the correct direction....