Sometimes when you arrive on site, there’s no error code displayed (LEDs blinking) and you’re not sure where to start.
On a wall-mounted air handler, the best thing to do is initiate the indoor unit error recall function mode. To do this, see the following steps below.
First, hold the MODE and TEMP+/TOO COOL button simultaneously.
Keep holding the MODE and TEMP+/COOL buttons and press and release the reset button
Continue holding the MODE and TEMP+ COOL buttons.
The remote display will change.
Aim the handheld remote at the wall mounted air handler unit and press the OFF/ON button.
Watch the upper LED on the wall mounted air handler and see if it blinks and emits a beep at the same timing as the blinking. If so, there is a saved error in the system.
Before blinking, does the upper LED stay solid green for 3 seconds? If yes, then the outdoor unit is abnormal (Check outdoor unit manual). If not then the indoor unit is abnormal.
Count the number of blinks/beeps and check the service manual for the table of indoor unit failure mode errors. This will tell you what is wrong with the air handler.