Furnace gas valve is not opening

Question edited for typos.

Gas furnaces has safety features to prevent explosions. If anything is thought to be faulty, nothing works. All gas appliances must be repaired by a registered gas technician. The two pressure switches are $76 and $29 if you want to risk it.

https://www.goodmanparts.net/category/goodman-gmv950905dxa-gas-furnace-oem-repair-parts

There is videos and help here. Check the hose on the pressure switch.

https://www.google.com/search?q=Goodman+GMV950905DXA++low+fire+pressure+switch+stuck+open

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possible burner tube blockage or flame sensor dirty or bad when fails see if voltage to keep gas valve open

Bad or dirty thermocouple

• What Is Electronic Ignition?

  Jupiterimages/Getty images The electronic ignition system in a gas furnace is a modern development that provides more reliable performance than a standing pilot and offers energy savings through better furnace efficiency. There are two basic types of electronic ignition systems:
  
  • An intermittent pilot system uses an electronically controlled high-voltage electric spark to ignite a pilot light and subsequently the main burners when the thermostat calls for heat.
  • A hot surface ignition system uses an electronically controlled resistance heating element, not unlike a light bulb filament, to ignite the gas burner.
  Understanding some of the basic components of a modern furnace will help you identify the type of furnace you have and narrow down the list of potential problems.
  
• 02of 05
  

  Types of Electronic Ignition Furnaces

  
  Design Pics/Getty images Most furnaces with electronic ignition are either conventional induced draft furnaces or high-efficiency condensing furnaces.
  Induced draft furnaces use a small fan to draw the combustion gasses from the combustion chamber and out of the house through the flue (chimney). This system is more reliable and safer than old conventional furnaces, which relied on a natural draft coming in from an opening at the front of the furnace. Induced draft furnaces use either an intermittent pilot (IP) or hot surface ignition (HSI) instead of a standing pilot light. The combination of electronic ignition, electronic controls, and artificially created draft improves the efficiency of induced draft furnaces over older conventional models.
  Condensing furnaces use two heat exchangers, where conventional furnaces use only one. After the gas is burned to heat the primary heat exchanger, the secondary heat exchanger draws heat out of the hot exhaust gasses, cooling them to the point that the water vapor in the exhaust condenses into water. The resulting flue gases are so cool they can be vented outside via a plastic (PVC) pipe, while the condensed water is run to a floor drain. Condensing furnaces use hot surface ignition (HSI).
  
• 03of 05
  

  Troubleshooting an Intermittent Pilot (IP)

  
  Michael Interisano / Design Pics / Getty images Typically found in induced draft furnaces, an intermittent pilot ignites the burner gas with a high-voltage spark only when the thermostat calls for heat. Once the pilot is lit, and the main burner senses the pilot flame (using a flame sensing rod), the main burner ignites. The intermittent pilot flame goes out after the heating cycle and remains off until the next time the thermostat calls for heat.
  The furnace gas valve for this type of furnace is identifiable with its solenoid designations: MV, PV, and PV/MV - where MV = main valve, PV = pilot valve, and PV/MV = common.
  Common problems with IP ignition include:
  
  • Ignition doesn't occur, and the furnace won't go on
  • A spark is present, but the pilot won't light
  • Pilot lights, but the main burner doesn't come on
  • Burners ignite but turn off after a few seconds
• 04of 05
  

  Troubleshooting a Hot Surface Igniter (HSI)

  The hot surface igniter (HSI) is the most commonly used electronic ignition system. It works like a light bulb filament, heating up when electricity is passed through it. Most are made from silicon nitride or silicon carbide. The igniter is located in the flow of gas entering the burners.
  When the thermostat calls for heat, 24 volts are sent to the electronic ignition control module, which energizes the furnace blower and other systems and sends 120 volts to the HSI. The HSI heats up to around 1,800°F to 2,500°F and glows red-hot. Then the gas valve opens, and the burner gas is ignited by the HSI. Once a proper flame is sensed by the flame sensor, the HSI turns off and stays off until the next heating cycle. In some furnaces, the HSI also serves as a flame sensor (called local sensing) instead of having a separate sensing rod in the burner flame (remote sensing).
  Under normal conditions, an HSI should last for three to five years, and they eventually crack and need to be replaced. This can happen sooner if the oils from your skin get on the element through improper handling. That means: Don't touch the element with your bare hands!
  HSIs usually cost between $25 and $50, and it's a good idea to keep a spare on hand, in case one goes out at night or on the weekend, when you can't easily get a new part.
  Here are some of the common causes of HSI failure:
  
  • Premature failure due to improper handling (oil from skin got onto element)
  • Improper igniter
  • End of normal usage life cycle (keep a replacement on hand)
  • Voltage in the furnace electrical circuit is too high (over 125 VAC)
  • Severely dirty air filter, causing the high-temperature limit switch to cycle the furnace ignition on and off frequently
• 05of 05
  

  Reading Control Board Codes

  
  Mohd Firdaus Mohd Damanhuri/EyeEm/Getty images Most modern furnaces with electronic ignition systems have an integrated circuit board that controls many sophisticated processes. The boards can perform self-diagnostics and provide failure codes, similar to the diagnostic computer in your car.
  If a failure occurs, LED lights on the control board light up in a blinking pattern to indicate a specific failure code. The codes are listed in a chart in the owner's manual and usually on a door or access panel on the furnace. Control boards are usually located inside the blower compartment of the furnace. If the board has blinking lights, refer to the chart to decipher the code and help identify the problem area with the furnace.

Furnace is the term we use for a gas system. I'm assuming you have an electric "air handler"(unit), and or has 1 element staying on, glowing red, and cycling on a limit. These elements are controlled by "heat sequencers", heat relays, and some older units used heat contactor's. This "switch" is stuck closed & must be replaced. I've also seen a direct short at the element itself, where the element has come apart, and a part of that element had touched ground. This completed the circuit and allowed the element the energize. Hope this helps! Its probably a stuck (closed), switch that's supposed to open when the tatat is satisfied.

It sound like the limit switch is shutting off and not coming back in to play .

Depends on the system,if it has 2 wire switch it can be bypassed,but only 1 time for each heating cycle if the system is using i pc board to operate the furnace,sometimes you can take the hose off and lightly suck and blow on it if the switch is stuck,but should have a pro check it,could be a blocked flue pipe or other dangerous problem,and could be a bad switch,did heating and cooling for 30 years

There maybe a few issues. They have multiple safeties on furnaces. With this in mind this process to find the problem would take a Technician to check these safeties. It could be a flame sensor or thermocoupler each senses a flame or heat to keep the gas going. Also the damper for the flue must open for the gas to stay on. There may be more safeties on this and each safety sends a 24 volt current back to control module in order for the gas valve to stay open. If these aren't being met it will try around three times and go into a lock out mode which will keep gas shut off entirely.

Heating Mode (Goodman Service Manual)

· The furnace control checks for an open main limit (this
limit is normally closed). If the limit is open, the furnace
will remain inoperable until the limit is closed. During
an open limit the circulating air blower will be
energized. The status light will blink four (4) times.
· The room thermostat reacts to a demand for heat.

· The control will then check to insure that the vent
pressure switch is open. If, at this point, the vent
pressure switch is closed the control will blink two (2)
times and will remain inoperable until this situation is
corrected.

· The venter blower is energized.· The vent pressure switch will close when it detects a
pressure in excess of its setting. If the pressure switch
fails to close the status light will flash three (3) times.

The sequence cannot continue until the pressure switch
closes.

· After a pre-purge of about ten (10) seconds the electronic
ignition device will be energized.

· After a slight delay the gas valve will open.

· The burners will ignite and the flame sensor will detect
the presence of flame. The ignition device will
deenergize. If the sensor does not detect the burner
flame, the gas valve will close and the ignition cycle
will be repeated for a total of three attempts. If, after
the third attempt, the presence of flame is not detected,
the furnace will go into a lockout condition for one (1)
hour. It will then repeat the ignition cycle. This one (1)
hour lockout and retry will occur indefinitely.

· Thirty (30) seconds after the main valve is energized
the circulating air blower will be activated.

· The furnace will remain in operation until the demand
for heat is satisfied.

· Once the demand is satisfied the venter will shut off,
and the circulating air blower will shut off after the field
selectable time off is attained.

· The furnace will remain dormant until the next demand
for heat.

It means that the furnace isn't igniting and for safety the control board is preventing the gas valve from opening. Turn off the power to the furnace for a few seconds then observe what the furnace does in heat mode. Some furnaces will run the blower for a minute after you power it back up. After that see if the furnace tries to come on. If you are still getting the code then one of you high temp limit or roll out switches has tripped. Now is the time for a service tech. Make sure that you check you filter and air flow too. Low air flow means the furnace may be over heating.
The other thing is the hot surface igniter. Look closely at it with the power off. Do you see a white spot on the element or a crack. If so the HSI is bad. It's an easy replacement but DO NOT touch the carbon element with your fingers and be very careful handling it as it is EXTREMELY fragile.