Returned to find out why customers dryer isn’t working when hooked up to the vent. Upon inspection we discovered that the 4 inch pipe and vent is totally clear. The dryer was moved from the basement to the 2Nd floor and flex hose was run through the wall to the basement and connected to the hard pipe. It appears the brand new flex hose is either pinched or caught up somewhere in the wall. I was unable to test this last time as the customer had to leave before I was finished. No charge.