This bulletin applies to all Honda models equipped with air conditioning. If the left dashboard side vent is warmer than the right side vent with the A/C on, chances are the evaporator core isn’t being flooded with enough liquid refrigerant, causing it to fully vaporize halfway through the core.
As a result, the side of the core with some refrigerant (the right duct) stays cold, while the side that is fully vaporized is warmer by about 20 degrees Fahrenheit or more.
The most likely cause is a low refrigerant charge, possibly due to a leak. Another culprit may be a restricted line or component that’s cutting the flow of liquid refrigerant.
To find and fix the problem, follow the A/C Performance leg of the online job aid A/C Diagnostic Process.