I arrived for a no cool call rental property. I spoke with the tenant and found that the system will run but it gets up to 80 deg during the day and cools off at night. I inspected the system and found the return plenum to have been poorly installed and is bringing attic air and trying to cool the temperature of the attic vs the temperature of the air through the return duct. I also found the drain line to have been swapped and stopped up. I bid to rebuild the plenum and fix the drain problems. The tenant will be in contact with the owners.