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kameronth's avatar
kameronth
Explorer
Mar 30, 2017

Suburban furnace - no spark issue

I have a 2010 Gulfstream TT. I tried searching the forums but majority of the issues I found were for no ignite problems.

My issue, I have no spark at all. The fan turns on under normal operation of the thermostat but the igniter does not attempt to spark - to simplify, it does not "click" at all.

Where/what should I check first? Should I remove the whole unit or are there test I can perform while it's still in place? The unit is a Suburban SF-xx - I'm not sure of the exact model number until I crack the unit open. Thanks.
  • On the SF series, I have found the most common failure is the limit switch- if you open the inside panel (not outside), it is right there. Often simply unplugging and replugging the leads will fix it, due to oxidation on the terminals. Next is sail switch.

    Sequence of operation-

    • Thermostat calls for heat
    • relay (or board) starts blower
    • sail switch closes at ~75% speed
    • board gets power- ~30 second purge cycle
    • board fires spark and opens gas valve for ~7 seconds
    • etc