TM 10-6640-215-13 Table 4-2.  Troubleshooting- continued MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION 14. AIR PRESSURE SWITCH CAUSING COMPRESSOR TO CYCLE ON AND OFF. Adjust pressure switch.  Refer to TM 10-4310-392-13&P. If switch will not adjust to operate properly, replace the pressure switch.  See paragraph 4-36. 15. VACUUM PUMP MOTOR FAILS TO RUN (POWER AVAILABLE TO MOTOR CONTROLLER). Step 1. Check operation of controller. If controller does not operate, refer to paragraph 4-27. Step 2 Continue to troubleshoot in accordance with TM 10-4310-391-13&P. If problem cannot be resolved, replace the vacuum pump.  See paragraph 4-37. 16. VACUUM PRESSURE LOW DUE TO LEAKS IN SYSTEM. Step 1. Check vacuum system piping, tubing, and unions for leaks. If leaks are found, repair or replace the leaking item.  See paragraph 4-37. Step 2. Check operation of vacuum pressure switch. 17. WATER PUMP FAILS TO RUN (POWER AVAILABLE TO MOTOR CONTROLLER). Step 1. Check operation of motor controller (refer to FO-1). Step 2. Check operation of water pressure switch. Step 3. If  controller  and  pressure  switch  are  operating  properly,  continue  troubleshooting  in  accordance  with TM 104310-391-13&P. If problem cannot be resolved, notify direct support maintenance to replace water pump. 18. WATER PRESSURE LOW DUE TO LEAKS IN THE SYSTEM. Check system for leaking piping, tubing, unions, valves, supply tank, surge tank, or pump. When leak is isolated, notify direct support maintenance to replace faulty item. 4-16