I installed an upflow air handler in a downflow configuration, as the HVAC retailer I bought it from said it would work. I flipped the coil over during the installation. The water appears to come off the coils during the cycle. When the cycle ends, water drains from the bottom of the air handler. I tried reducing the speed of the fan motor, which helped but did not eliminate the water coming out at the end of the cycle. I've seen air handlers that could be installed as upflow or downflow. Are the coils on those units different? How do I eliminate the water?
You probably should not have flipped the coil over unless the install instructions said to do so. The air can flow either way, but the water will always try to go downhill to the drain pan. Air going backwards through the coil will affect performance noticeably if it is more than two rows thick, in which case there will be some sort of means to address the drain issue - either a separately purchased kit or moving a pan or baffle that was shipped with or installed in the unit. The install instructions should have the details.