Arrived to clients concern that the sink was backing up and that he did not receive an algae stick with his maintenance. I confirmed that we did in fact blow out the drain line on our previous visit. I proceeded to the attic and replaced the algae stick. While in the attic I found a dead rat on a trap and informed Paul. He will call pest control to remove the body. I checked the primary drain line and confirmed it did not have any backed up water nor evidence of clogging. I had some slight resistance but I discussed with Paul how this may only be isolated to the sink and not the havc drain. The unit is draining properly on departure.