Keith D. Geothermal closed loop system issues

Climatemaster Genesis Geothermal 2001 installation. Closed loop system. 3 ton. Warm air system. 3 wells. Water furnace external circulators (2) 1 internal circulator.
Not cooling. Locks out after about 2 minutes. ***** system tests OK. Internal circulator to draw 4 amps. No draw. Power to circulator tests OK. Circulator failure suspected. Also mentioned the possibility of coil corrosion + blockage potentially causing increased pressure, causing circulator failure. Closed loop with antifreeze mixture, never opened since installation. If circulator failed will replace. What is expected life of coil? How often does a 12 year old system have coil blockage? If coil is blocked is the unit junk? Would very much appreciate response.
Keith D.