128 Supply Air Temperature Probe Error MP4000

Description 

Supply Air Temperature Probe Error 

• Occurs during pretrip (PTI) test and probe test only. 
• After ventilation with the evaporator fans. 
• If the supply and return air temperature sensor differs more than 1,5C and the return air temperature is within 1,5C of evaporator coil temperature. 
• If evaporator coil temperature sensor is failing, if the supply and return air temperature sensors differs more than 1,5C. Both alarm 129 and 128 will be set. 
• Indicates: 
• Failing sensors. 
• Misplaced sensors. 
• Failing controller. 

Corrective Action 

• Use the DATA menu to detect the failing sensor. 
• Replace sensors. 
• Use the tester to determine the problem.