I was hired by a GC to replace 3 HVAC systems in a burned out church. A mechanical permit was pulled by our Company and 50% of the signed proposal was paid. A city inspector conducted a preliminary inspection because the GC would not provide access to the new location of the replacement equipment stating we had to entail the cost. After 4 days the GC complied with the inspector request to provide access. At 95% completion of the project a cover-up inspection was conducted and pointed out that motorized fresh air would have to be installed for the project to pass the final. A change order was sent to the GC for the installation of the motorized fresh air dampers. The GC stated he was paying the change order and if we did not install the motorized dampers by a certain date we would be fired off the job. Two days later the GC went to the City and terminated our permit and would not let us access the building to finish the project. A final bill was sent on that date.