TM 5-6115-590-12 Table 4-2.  Troubleshooting-Continued MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION 19.   HOT WATER EXCESSIVELY HOT TURNED TO STEAM. Step 1. Check exhaust gas flow control valve. Replace flow valve.  (fig.  4-29) Step 2. Check    hot    water    temperature    switch    (S12) Replace temperature switch.  (fig.  4-26) 20. VENTILATING AIR SYSTEM WILL NOT START. Step 1. Check for 400 Hz power. Refer  to  figure  2-14  for  operation  to  deliver 400 Hz power.  Replace failed components as required. Step 2. Check  recirculating  fan  circuit  breakers  (CB15 and CB16). Reset    circuit    breakers.        Replace    circuit breakers as required.  (fig.  4-22) Step 3. Check vent system select switch (S14) Replace switch (S14).  (fig.  4-21) Step 4. Check mode select switch (S16). Replace switch (S16).  (fig.  4-21) Step 5. Check    recirculating    fan    contactors    (K25)    or (K26). Replace contactors as required. Step 6. Check diode (CR12). Replace diode (CR12). 21.   HEATED     AIR     SYSTEM     WILL     NOT     DELIVER HEATED AIR. Step 1. Check for 400 Hz power. Refer  to  figure  2-14  for  operation  to  deliver 400 Hz power. Step 2. Check recirculating fan circuit breaker (CB15) or (CB16). Reset     circuit     brewers.          Replace     circuit breakers as required.  (fig.  4-22) MALFUNCTION TEST OR INSPECTION CORRECTIVE ACTION Step 3. Check heat system select switch (S31). Replace switch (S31).  (fig.  4-21) Step 4. Check mode selector switch (S16). Replace switch (S16).  (fig.  4-21) Step 5. Check load control valve. Replace load control valve.  (fig.  4-28) Step 6. Check air pressure regulator. Replace air pressure regulator.  (fig.  4-28) Step 7. Check load control thermostat adjustment. Refer   to   paragraph   4-14e(1)   for   proper   adjustment procedure.  Replace thermostat.   (fig.  4-28) Step 8. Check heat temperature sensors (RT1, RT2, RT5, RT6). Replace temperature sensor as required.  (fig.1-7) Step 9. Check heat system flow control valve. Replace flow control valve.  (fig.  4-29) Step 10. Check overtemperature thermoswitch (TS5) or (TS9). Replace thermoswitch as required.  (fig.  1-7) Step 11. Check diode (CR15) or (CR16). Replace diode as required. Step 12. Check to see if jumper plug (J93) is installed. Install or replace jumper plug as required. 22.   COOLED AIR SYSTEM WILL NOT DELIVER COOLED AIR. (Refer also to malfunctions listed under item 20) Step 1. Check sight glass. If   refrigerant   is   low,   refer   problem   to   direct   and general support maintenance. Step 2. Check solenoid valves, pressure controls and lines. Refer problem to direct and general support maintenance. Step 3. Check  compressor  time  delay  and  reset  relay  (K17)  or (K18). Replace relay as required.  (fig.  4 22) 4-24