Arrived for zoning issues. System has 2 systems and 3 thermostats. Downstairs has its own system. And the main floor and upstairs are zoned a serrated system. Top floor thermostat wouldn’t respond to any calls for heat and main floor thermostat would over heat the upstairs and wouldn’t sufficiently heat the main floor. We discovered the thermostat upstairs had bent pins. Not sending call for heat to zone board and the zone damper for the upstairs was disconnected and was always open. Sendingnprimary airflow upstairs. We also discovered gas pressure very high, along with dirty blower wheels, undersized duct work and a semi dirty air filter causing the system to occasionally trip high limit. Gas pressure was adjusted, zoning was restored and thermostats are both responsive and operational again. System has a breached heat exchanger and is 20 years old and approaching failure. We discussed long term solutions and she said she will start to think about the long term solutions after the upc