Question:
I have two (identical) Coleman roof air conditioners. The front one
ices up in about two hours (Airzona in October), stopping the air
flow. The ice is visible by removing the interior shroud and shining
a flashlite past the fan onto the chiller coil. The ice was worse in
Florida, presumably because of the higher humidity.
The back AC does not freeze up, which suggests that there is something
in the unit that is supposed to prevent it from icing up that is not
working in the front AC.
Does anyone know what it is that is supposed to prevent icing of the
chiller coil? I've had the top off and looked at it, but nothing is
obvious to me.
Answer:
THE MOST COMMON cause of icing in an RV roof mount A/C is the
refrigerated air leaking directly back into the return air. Remove the
ceiling assembly and with foil tape (don't use duct tape) seal the cold
air outlet duct so that none of the "chilled" air can leak into the
return air path. Secondly in high humidity situations you may need to
run the fan on the high setting only, however I suspect your problem is
most likely related to internal air leaks. This is a lot cheaper than
recharging the A/C and is something the average do it yourselfer can
handle. You didn't say whether your unit has duct work in the ceiling,
if it does make sure the ducts are open and clear ( remove ceiling
grills and inspect with a mirror in one hole and a flashlight in
another) and that the transition of the airflow from the roof unit into
the ducts are smooth and well sealed.
