TM  9-2350-256-34-1 3.  Energize   power   supply   and   turn   on switches  A  and  B.  Manually  adjust  voltage  to  20 and then to 28 volts, and allow blower to run 15 to 30 seconds at each voltage. Blower must run freely. Overhaul  blower  if  there  is  evidence  of  binding  or wear, or if there is any noise which would indicate rough or defective bearings. 4. With  switches  A  and  B  still  closed,  adjust power  supply  to  24  volts.  Ammeter  should  read  as indicated in figure 3-10.13. Determine blower speed with  tachometer.  Speed  must  be  within  indicated range. 5. Turn off switch B and turn on switch C. Wait 20 to 30 seconds for blower to slow down. The blower must run smoothly and steadily, but it is not necessary to check motor speed or current draw. 6. Turn  off  switches  A  and  C,  and  shut  off power. Disconnect blower from test equipment. (m) If  voltage  limiter  was  not  tested  during blower   overhaul,   test   it   now   before   reassembly. Follow   procedure   described   in   paragraph 3-35b(1)(d).  Voltage  limiter  may  be  tested  without removing it from blower housing since flag terminal is  accessible.  Voltage  limiter  is  grounded  through blower   housing. (4)  Heat  exchanger  assembly  installation  (fig. 3-10.2). (a) Connect one end of the ground lead assem- bly (12) to the heater housing (28), and secure with a nut (14) and lockwasher (13). (b) Spread  the  heater  housing  assembly  and insert   the   heat   exchanger   assembly   (15)   in   the housing. Install the four screws (34) that secure the housing  seam. (c)  Connect  the  other  end  of  ground  lead assembly (12) to the heat exchanger and secure with screw  (11). (5)  Flame   detector   switch   installation   (fig. 3-10.7). (a) Insert the ceramic rod (fig. 3-10.7) into the tube. Flip the microswitch back into position and in- stall the adjusting screw. (b)  Slowly  turn  in  the  adjusting  screw  (fig. 3-10.7)  until  the  switch  just  clicks,  then  exactly  ½ turn more. Secure the adjustment by sealing the ad- justing screw with G.E. Glyptal varnish, No. 1201. (c) Install  the  flame  detector  switch  (21,  fig. 3-10.2)  in  the  heater  and  tighten  the  compression nut (22) on the underside of the switch, making sure that the switch assembly is positioned crosswise to the axis of the heater so that the guard can be in- stalled. (d) Connect the wires to the NC and NO) con- tacts on the switch and secure with the screws (20). (6) Igniter installation (fig. 3-10.2). (a) Be sure the seal (35) is seated in the top of the heater housing (28). (b) If a new igniter is being installed, connect the shorter lead to the ground terminal (31) on the top  of  the  heater.  Connect  the  longer  lead  to  the ignition  control  (25). (c) Install the igniter (9) in the igniter tube (8). Use  a  screwdriver  with  a  long,  thin  blade  to  press the element end of the igniter firmly into the igniter tube  to  ensure  that  the  igniter  is  firmly  seated. (d) Press  the  igniter  down  and  turn  it  clock- wise to engage the pin on the top of the igniter with the slots in the igniter tube. Reinstall the electrical inlet   assembly   (36)   and   secure   with   the   Dzus fasteners. (e) Reconnect electrical cable to the heater. NOTE If   the   igniter   requires   frequent replacement,   test   the   operation   of   the voltage limiter as described in paragraph 3-35b(1)d.  An  inoperative  voltage  limiter allows  surges  of  high  voltage  from  the ignition control to damage the igniter and shorten  its  life. (7) Ignition control installation (fig. 3-10.2). (a) Slide  the  new  ignition  control  (25)  under the two loosened screws (17), install the remaining two screws, and tighten all four screws. (b)  Route  the  ignition  control  lead  through the  bundle  of  wires  and  connect  it  to  the  flame  detec- tor  switch  (21).  If  the  fuel  control  valve  (26)  was removed, reinstall it, as below, and bundle the wires with two cable assembly straps (37) or lacing cord, one on each side of the fuel control valve mounting bracket. (c)  Connect   the   igniter   lead   and   voltage limiter  lead  to  the  spade  terminals  on  the  ignition control. (8) Fuel control valve installation (fig. 3-10.2). (a)  Slide  the  fuel  control  valve  mounting bracket  under  one  screw  (27)  and  engage  the  fuel tube  (5)  in  the  outlet  elbow  on  the  control  valve. Start the compression nut (6) on the elbow, then in- stall  and  tighten  the  remaining  two  screws  (27). Tighten  the  compression  nut.  Check  that  all  the loose  wires  are  retained  between  the  fuel  control valve mounting bracket and the heater housing. (b) Connect leads 3, 5, and 30. (c) Bundle the wires and secure them with two cable  assembly  straps  (37)  or  lacing  cord,  with  one strap  on  each  side  of  the  control  valve  mounting bracket. (d) Connect the fuel supply line to the IN port 3-18.28 Change 2