LAARS NeoTherm NTV (Sizes 399-850 MBTU/h) - Service Manual - Manual (Page 23)

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Service Manual - NeoTherm 500
10. Check for 24V AC between terminal J6-1 on the
control module and any terminal on TB4. See
Fig. B1-6. If 24V AC is present here, this means
that the following safety switches are OK:
• High gas pressure switch
• Low gas pressure switch
• Condensate trap level switch
If 24V AC is not present, troubleshoot the three
components:
• Section B12 - High Gas Pressure Switch
• Section B13 - Low Gas Pressure Switch
• Section B16 - Condensate Trap Level Switch
11. If you see 24V AC at J6-1, this means that all
of the switches in the safety chain are satisfied.
The blower should run, and then the pressure
switch should close, allowing the ignition se-
quence to start. To check the pressure switch,
check for continuity (no resistance) between ter-
minal 1 on J6 and terminal 1 on J5 on the control
module. See Fig. B1-7.
If the pressure switch remains open, go to Sec-
tion B19, “Checking the Air Pressure Switch.”
Fig. B1-6 - Checking the safety switches
Fig. B1-7 - Checking the safety switches
Quick Check of Components in the
Safety Chain - continued
B1
cont.
J6-1
J5-1
J6-1