The induction fan motor comes on to clear the heat exchanger tubes, but the gas valve never opens, the hot surface ignitor doesn't heat up, the rollout switch is not in reset. I've ohmed it out, it is closed. unit will not ignite. what to check next?

Check the gas valve is opening fully . Also check you are getting full gas from your gas line ie the reg outside . or if you are on lpg the gas is not low . check all vales are fully on the gas line .

This is a down flow unit. There is no pressure valve on this unit. Here is all the parts on this unit.
1. Manual - reset, when used.
2. Blower and blower motor
3. Relief box also known as a exhaust flue.
4. Gas valve control knob or electric switch, ON/OFF
5. Gas Valve
6. Gas burner
7. Ratting plate
8. Blower door safety switch
9. Blocked vent safeguard tube and switch
10. Gas Manifold
11. Manual limit switch (2)
12.Hot surface ignitor
13. Flame sensor
14. Inducer blower motor
15. Control board with relays and transformer.
That is all the parts. The first thing the heater gets a call from the thermostat to the control board marked W. The board sends 24v to the inducer fan relay which makes and causes the inducer fan to come on now there is a small tube that runs from the inducer fan box to a switch when the switch makes it sends power to the board which proves you have cleared the exhaust flue then the flat surface ignitor starts to glow and then gas valve opens and fires. now if this tube is stopped up the heater will not fire and will lock the unit out. Also if the flue is stopped up with trash it will do the same thing. If you are not familiar with gas heating units you should call a service company out and check out the system there is a lot of things that need to be checked out every heating season as to keep you and your family safe.

on most of goodman equipment they have on the door panel or on the actual label inside the furnace what that code actually means... the sequence of operation is as follows though...
the thermostat calls for heat if a digital thermost can take up to 5 minutes..once the call is made the enducer draft motor comes on located in the burner side(small fan) it will run for approx 20-30 seconds and then activates the negative pressure switch which is round and has a plastic tube coming from the enducer draft housing and connected to the pressure switch. the pressure switch once activated then will bring on the hot surface ignitor (porcelien glow plug looking device in behind burner assembly) once the hot surface ignitor gets red hot it milivolts back to the board are sent to the gas valve to open and light..there then should be a metal rod also behind the burner that senses the flame called a flame sensor and keeps the gas valve opened if current there. after heating up to temperature the blower motor should come on.there also is limit devices on the side of burners called roll out limits usually resettable by pushing the black buttons in the middle. there is a high heat limit going into cavity looks like cardboard with 2 prongs but if bad usually will keep fan running all the time there is also a blower limit attached to the blower motor housing that should be closed unless bad... unplug unit and watch it where does it fail/also look for code and repost if you need more help.

Sounds like a faulty board. shut the power to the furnace off for a minute then turn it back on. Make a call for heat at the thermostat. The inducer should start and close contacts on a pressure switch . Once pressure switch closes the hot surface ignitor should glow red. Then the gas valve will open when the gas valve opens you should get fire till the stat is satisfied. If your concerned it is the jump out r to w on the board this will eliminate the stat. If you to reset the rollout switchs 3 timesyou're getting flame rollout and you either have a cracked heat exchanger or blockage in the exhaust piping or a bad inducer motor. Keep me posted with what you find!

It sounds to me like your gas valve is bad. If you can get induced draft motor to come on then Hot surface ignitor to come on the next step should be lighting burner. I would check to verify that you have fuel to unit and if you do I would reccomend you get a new gas valve. Hope this helps. Thanks

From what I saw when I googled you furnace it has a hot surface igniter. It only gets hot when it's time to light the furnace. You should be able to see it glowing red when the furnace is trying to light. The furnace has a safety feature which shuts the gas valve when it doesn't detect a flame to prevent gas build up in the furnace. There are other safety features also. If the draft inducer motor isn't running the gas valve won't open. Overheat switches some of which have to be reset manually. Adjust the thermostat until it calls for heat then observe what is or isn't happening in the furnace. It will go thru a purge cycle first. The draft inducer motor will run to do this. After the purge the hot surface igniter should get hot a glow, then the gas valve will open and the burner will light. Let me know what you find.

Hi, this unit if you say hot surface ignitor has no standing pilot for you to light. Yes, the fan will run in the on position. Turn it back to auto. Leave it off. You will need 2 people, this will be easier for you. Go to the furnace and see if you have a round inspection hole to look through. If so, see if you see a red led light. Yes or know. Remove the panel to where you can see the circuit board, burners lined up and so on. Some units have a panel switch on them so when you remove the panel, it kills power to everything. It would be around the perimeter and you will need to tape it down real good. Now, have someone turn the thermostat to auto/heat and turn the heat up high. I know this is a Carrier with a hot surface ignitor, so you should be hearing the small inducer motor start running. If you did have a red led light and it is flashing, you will have a code sheet glued to the panel, a error sheet to tell you what is wrong, like if its flashing 3 times fast and 1 time long and slow you would look at chart and it will say what to look for. Some units have them and some don't.Anyway, the inducer motor comes on first, it has a clear plastic tube coming from it going to a pressure switch. If the motor is on and the tube is clean, no water, condensation in it, it goes to the switch and closes the switch.When it closes, it will send a command to the main controller, circuit board or a module to send power to the hot surface ignitor, which will glow and send a signal back to open the pilot valve(PV). There is a porcelin flame sensor next to the ignitor that has a metal tip which heats up and tells the main gas valve the pilot is on to open up and send gas from the 1st burner over to the 2nd and so on. This is the sequence of operation. We know the stat is good, and the blower motor is also good, so all we need to do is find out why the furnace wont light and run. It may have a flame roll out switch on it that has tripped. It has a reset button on it. Make sure the gas valve and gas is on before you do this test I am walking you through. Try to have a helper. Remember the door switch if it has one. This should be a easy fix, so get back to me and keep me posted on what is going on. I will wait to hear from you. You can do this.
The best to you,
Shastalaker7

The sequence is Igniter comes on, valve comes on, flame sensor senses flame. If no flame is sensed after 3 tries, a lockout occurs. If you have a volt meter, check for 24-27 Volts AC coming to the gas valve, if your getting voltage to the valve but no gas, your gas valve is defective. It could be a intermittent problem, no matter, still a bad valve. if no voltage to valve, defective circuit board. 

sounds like a gas valve issue. if the hot surface ignitor is glowing red then the next step is for the gas valve to open, if it doesn't then it sounds like the valve, if it does open but only for a few seconds then it is your main burner flame senser.

if the flue is warm that would indicate that the flames lit for a short while. furnaces sometimes have limit switches that shut down the gas if the heat exchanger gets too hot. I would verify you have clean filters. and all registars open fully.
If the flames are not lighting verify gas valve is recieving the 24vlts. to open.
Also check ignition system it will be a piolet light or hot surface ignitor. you should be able to see both without much trouble. hs ignitor should get bright cherry red.