Upstairs unit. Changed filter. Clean drain. Check all electronic components. Checked all safety switches. Clean flame sensor. furnace running as it should. Basement unit. Changed filter. clean drain. Checked amps on heat strip and blower motor. Both test fine. Checked all electron components. Basement unit working as it should. Main level unit. Change filter. Clean drain. Checked all electronic components. Checked all safety switches. Clean flame sensor. Furnace running as it should. Talk to customer about changing filter more often. Talk to the customer about there are 22 systems. Customer says it gonna let them run until they die. Two ACs are 06 models.