Tech performed CMA full service on 3 Gas Package Units, 2 Air Make Up Units, and 6 Exhaust fans. Upon inspection tech found the gas pressure to all package units low. Tech was able to adjust units 1 and 3 to proper pressure but due to corrosion fusing the gas valve adjustment screw closed was unable to adjust unit 2. All systems are running properly at this time. Tech has attached system performance reports and pictures to this invoice.