I need help troubleshooting Tempstar furnace Honeywell ST9162A 1040 Board

Blower: DC motor Variable speed Speed Control: Emerson X177265620004

Symptom: No Inside blower in Cool mode.

Outside AC is working fine. Inside blower will not work.

Thermostat: Replace new, same issues.

  • Tstat switch set to Heat, and Fan set to AUTO, Heat runs normally: Inside Blower/Fan starts and runs normally. Then, set Tstat system switch to off then Blower shuts off.

  • Tstat System switch set to Off, and Fan set to On, Blower runs normally (continuous).

  • Tstat System set to Cool, and Fan set to AUTO, outside AC run normally, inside Blower did not run then turning Fan to On inside Blower remains off.

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  • Did it used to work?
    – gnicko
    Jun 10, 2023 at 0:10
  • 1
    Does this help? diy.stackexchange.com/q/66799/25178 Or this? diy.stackexchange.com/q/69989/25178
    – gnicko
    Jun 10, 2023 at 0:13
  • @gnicko yes. It did work last year. I read these post and it a bit different with mime. My Blower connect with speed control instead of connect direct to control board, so I do not know how to test blower by pass controller to make sure blower is good or not.
    – Victor
    Jun 10, 2023 at 3:11
  • "Blower runs normally (continuous)." - I'd assume blower motor and its start/run capacitor are both good, but ECMs are not my specialty. On old ones, AC always hooked to the high speed line, heat was a choice where. Do these have a bypass wire that tells it to goooo ?
    – Mazura
    Jun 10, 2023 at 22:42
  • 1
    Hi @Mazura thank you for the suggestion. I connected R and Y on both Tstat and on control board. AC on and run well. I connected R and G fan run but I connected R to both Y and G just AC run blower did not run at all. Yes that is old 2 stages unit with ECM (DC motor, it has 4 wires Red, Yellow, Blue and Green).
    – Victor
    Jun 12, 2023 at 4:25

1 Answer 1


Let's summarize.

TH +FA = all runs Heat mode

TF = F-runs Fan only mode

TC + FA = F does not runs Cooling mode

Would say your control board is fine, but it is getting signal not to run.

That would indicate the drip pan water overflow sensor is active. It is ignored in heat mode, it is ignored in fan only mode, but it is used in Cooling+Fan mode.

A quick Test:

Use pice of wire and bridge the Y an G

T - Thermostat F- Fan C- cooling H- Heating A- Auto mode

  • Thank you for the summarize. It is correct! I am newbie and first house owner, so can you please show me where is the drip pan water in the furnace? I’ve looked around but not yet found.
    – Victor
    Jun 10, 2023 at 3:56
  • Just below the Indoor Fan, it should have a drain pipe coming out. See the white pipe, follow it to find the drip pan, and there should be the level sensor. Once you find it, just unplug it and see if the C+F is working now
    – Traveler
    Jun 10, 2023 at 4:37
  • "Tstat System set to Cool, and Fan set to AUTO, outside AC run normally, inside Blower did not run then turning Fan to On inside Blower remains off." - it should be in complete lockout then, or actually running nothing but the air handler to melt the block of ice on the coil. Isn't the drip pan water overflow sensor just in series with the call for cooling? So that when it's leaking, it stops the condenser outside from making more water inside. With condenser running and no blower, you're making ice inside, then it locks out and starts dripping water everywhere.
    – Mazura
    Jun 10, 2023 at 22:39
  • I suspected the high speed line on the blower motor but it's variable speed.
    – Mazura
    Jun 10, 2023 at 22:39
  • @Mazura however the Fan is running in Fan only mode
    – Traveler
    Jun 10, 2023 at 23:10

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