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.Honeywell SV9540 Troubleshoot advice requested (NO HEAT)

Good Morning all,

I have a Honeywell SV9540 Gas Valve with the ST9160 Electronic Fan Timer. The * tells commands heat, I hear one realy click on the ST9160 and that is all. The start up fan does not come on and the ign. stays off, and I have a steady blinking light.

I do have 24VAC at the SV9540 * switch.

The AC Works

The Fan Works

The Fuse is good.


1. How can I prove all my safety switches are ** (open or short)

2. Is there suppose to be any voltage going to the relay (black and white wire) on the SV9540 when the * has heat * (I have zero volts all the time, I believe this is my problem)

3. I checked all heat switches and they all read zero ohms (short) which is good.

Any and all information to help prove or * the GAS valve will be Greatly appreciated.

Thanks in Advance,



  • Tim McElwain
    Tim McElwain Member Posts: 4,580
    Sounds like

    the combustion air blower is not coming on. It is powered off the C3 terminal on the SmartValve. Do you have 120 volts at L1 and Neutral on the C3 connector? If yes then with the thermostat calling do you have 120 volts on the other side of the C3 connector? If you do that is the feed to the Combustion Air Blower. Then go to the combustion air blower, do you have power? If so and the motor is not running you need a combustion air blower.
  • chargedbird
    chargedbird Member Posts: 2
    NO Voltage


    at L1 and Neutral on the C3 connector.

    After reading all the stuff on the internet, I am thinking that the igniter is not working or not reporting back that its working.

    When I command heat, I get the red light on the t-stat and I hear one realy on the ST9162A Board energize and that is all..no nothing, no spark, no glow, nada....

    I ohmed out the the igniter wires and they are good and I cleaned the igniter.

    Thank for you help,
  • Tim McElwain
    Tim McElwain Member Posts: 4,580
    No power at

    L1 on C3 then do you have 120 volt power at the ST9160 if you have a ST9162 then you have a two stage system which is it?

    The power for C3 comes from the board on the 6 pin white connector the top two pins? If you have 120 volts to L1 to neutral on the board and the thermostat is calling then you should have 120 volts at the top two pins if not the board is bad.

    What you have happening has nothing to do with the igniter on the pilot.
This discussion has been closed.