Our house has 2 Lennox G40UH(X) furnaces w/attached evap coils in 'top' section (units horizontally suspended from rafters; air handler mod # not known). The placement of the strapping suspending these units make it appear that unscrewing the access panel would cause the casing to fall apart. Maybe you have insight on how to open the panels 2 clean the coils. Thanks in advance for your help.