Trying to set my goodman gmvc9570 two stage furnace to low fire all the time but do not have the manual to show me how can u help

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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If I remember correctly, there are dip switches on that control board that can be set individually. It is possible that it is just a setup issue. The switch positions should be explained in the installation instructions. I know that some Goodman and Amana two stage furnaces can be controlled by a single stage thermostat, but the dip switches have to be set properly. If the switches are set correctly the furnace will run in low stage heat for approximately 5 minutes and if the thermostat hasn't satisfied yet, it will kick in to high stage heat. I hope this points you in the right direction!

Hi Dave. I'm Roger. Its normal for a furnace to shut down completely when the set point on the thermostat is reached. The first and second stages are used when the temp. gets close to set point. The heat output drops to its low stage at around 3 degrees before set point. Check your owners manual for specifics on the fan though.

It wouldn't be stuck if that's the case the valve would never shut off. Sometimes those 2 stage heat thermostats stats call for 2nd stage if the room temp drops more than 2 degrees. Easiest way to check is take the w2 wire off of the tstat and try a call for heat. If the furnace kicks on both 1& 2 stages then its either your wiring on the fan board or a dip switch setting. If it kicks on 1stage then it's your thermostat.

Gerge, if you go to website www.energycodes.gov
you can do a heat load calc yourself. Basically, you figure out the sizes of walls, total area of glass. total doors to outside, ceiling area and types of building materials used. It is pretty easy and then you will know for sure. The contractor should be suppling you with one but if not use this, it is free!

Some questions for you, did you adjust the Low stage gas pressure first and is is about 6" W.C.? Then did you adjust the High stage and is that about 10" W.C.? If the gas pressure is correct and the dip switch is on 2 stage, the unit should fire on both low and high fire for about 5 seconds then drop to low stage. If it does not, check the hoses going to the pressure switch for a leak. Test the high pressure switch when the unit tries to go into high stage to see if it is closing. Do not blow into the hoses or you will need new pressure switches. If it proves a closed switch, you will need to check for voltage at the gas valve. If you get none, replace the circuit board. If you get 24 volts at the orange wire hooked to the Hi side of the gas valve, you have a bad gas valve.

my guess would be a problem with the low voltage wiring a short have it checked out by an electrician

You should NEVER attempt to relight manually this furnace. Serious burns could be the result. This furnace has an electronic ignition and should light by itself. If it does not light you may have a bad ignitor. These are usually around 30-50 US dollars.