TM 9-4940-342-14&P Table 5-1.  Troubleshooting - Continued Malfunction Probable Causes Corrective Action 3.   Air pressure switch contacts open. Inadequate  air.  (Switch  closes  at 0.15 WC) - Continued d.  Switch setting in- correct - Continued too    high.    Decrease    set    point    by turning adjustment coun- terclockwise    until    burner    ignites. Test  trip  out  point  as  indicated  in this corrective action. e.  Switch diaphragm ruptured. e.  Air will emit from open vent side of switch. Replace switch. f.   Fan rotation incorrect. f.   Observe  motor  rotation.  Should  be clockwise  when  viewed  from  front (pulley     end)     of     motor.     Correct rotation  by  reversing  any  two  of  the three 3-phase power leads. g.  Fan belt loose. g.  Inspect  belt  for  tightness.  If  it  can be  twisted  more  than  2/3  of  a  turn, tighten belt by adjusting oil pump in slots in mounting base. h.  Improper air gate adjustment. h.  Inspect  air  gate.  Open  air  gate  until sufficient    air    for    combustion    is available.    Observe    exhaust;    black smoke, insufficient air; white smoke, too much air. i.   Blower cage loose on shaft. i.   Remove  air  gate  and  blower  intake screen.   Inspect,   align   and   tighten cage with setscrews in cage. j.   Blower drive pulley loose on shaft. j.   Inspect    pulley.    Remove    belt    and tighten     pulley     with     setscrew     in pulley. 4.   Inadequate water supply, low water pressure switch open (needs 15 psig to close) (refer to malfunction 1). a.  Water supply tank empty or par- tially full. a.  Observe  water  level  in  tank.  Check adjustment   of   float   valve   and   for adequate   pressure   and   volume   of water at supply source. b.  Pump on-off suction valve closed or partially open. b.  Inspect position of valve handle and that valve is in full open position. c.  Suction valves, lift and water tank, open at same time. c.  Inspect   position   of   valve   handles. Leave  valve  to  the  desired  suction source open, close other valve. d.  Water tank pump suction nipple off or loose. d.  Inspect nipple, replace and/or tighten nipple. e.  Pump suction strainer is plugged. e.  Remove  and  inspect  strainer,  clean and replace. f.   Air leaks in pump suction piping. f.   Inspect    piping    for    loose    fittings, hoses,    hose    clamps,    etc.    Inspect suction  valve  bonnets  for  tightness. Tighten fittings. g.  Soap solution metering valve closed (lift suction connection only). g.  Inspect valve position. Open valve. h.  Soap solution tank dry (air being drawn into pump cylinder). h.  Observe    tank    solution    level.    Fill soap solution tank. i.   Ruptured bellows on pressure switch. i.   Water leakage around switch bellows assembly. Replace pressure switch. j.   Sensing connection for pressure switch plugged. j.   Remove    capillary    connection    and fitting at sensing connection on pipe cross    of    coil    inlet    assembly    and inspect   for   foreign   material.   Start water pump and flush out connection and replace. k.  Switch setting incorrect. h.  Observe set point indicator on scale. Cut-in   setting   should   be   20   psi, cutout setting 5 psi. l.   Air dome drain valve open. i.   Observe  valve  position.  Water  will emit from drain. Close valve. 29