On arrival, customer reported that focus pro is new and was installed on old 2009 model Trane system. Says he noticed 2009 Trane outdoor unit running, but did not hear blower. Tech checked focus pro settings and found them correct. Changed aux heat cycle rate for electric instead of gas aux heat cycle rate. Variable speed blower inside 2009 Trane AHU ramped up and responded correctly. Runs on low for 3 minutes and ramps up to higher cooling speed after time delay. Checked refrigerant pressures and found system severely low on R410a. Switched to heating mode to confirm. Distributors freeze immediately. There is a sticker that reports a fluorescent dye has been added in the past. Indoor coil appears to have been replaced in the past. Tech estimated 2009 Trane system is 4-6 lbs low on R410a. Tech confirmed that indoor coil inside 2009 Trane AHU is leaking refrigerant. See video and picture of green dye. Tech recommends system replacement due to age of system and cost of non warranty c