Goodman GMV95 gas furnace not lighting


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Old 11-24-14, 05:27 PM
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Question Goodman GMV95 gas furnace not lighting

I have a Goodman gas furnace GMV95 that was installed 3-4 years ago. Just started first time this season and no heat. A/C working fine. Trying to learn about furnace operation now so excuse ignorance of terms. RobertShawRS6220 stat installed w/ system. When stat is set to heat, small furnace fan (inducer??) comes on, igniter glows orange, and nothing happens...igniter goes out, inducer fan stops, and cycle repeats a few times until I turn stat off. Do not hear anything from gas valve (no click or switching). Any ideas?? I do not know proper sequence of events for furnace to light. I have DVOM and wire schematic is on inside of access panel. I have 20 years automotive diagnosing / repair experience so not totally lost...yet Any help would be appreciated. Thanks
 
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Old 11-24-14, 05:41 PM
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Welcome to the forum!! Here is a link to some info on your furnace:

http://www.acdirect.com/media/catalog/files/IO-280D.pdf

The normal sequence of operation is on page 32. Do you have a flash code showing on your control board?
 
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Old 11-24-14, 05:50 PM
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Red LED is on steady...and then 1 blink. System lockout?? I'm not sure how to access codes. Do they just blink on their own or do I need to do something to start the process?
 
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Old 11-24-14, 05:52 PM
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Yes, one flash is a lockout. You can shut power off and then back on to re-set the system. In the manual I linked there is a list of the flash codes. When you re-set the furnace set thermostat to heat and watch the control board to see if it throws a flash code. I suggest you remove the hose from the pressure switch and make sure it is clear from end to end. Where the hose attaches to the inducer there is a pressure port with a small hole in it. It can get crud in it and cause issues. I suggest you ream out the hole with an opened paper clip or small drill bit making sure it is clear all the way through.
 
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Old 11-24-14, 05:59 PM
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Shut power off...just unplug for 30 sec. or so?? Furnace is at moms house...1 mile away. I'm going over in a little while to check. After reset, if any codes, will just start flashing automatically after stat set to heat?? How long will they flash? Stat is in living room, furnace in attic...not best working conditions to get to quickly. BTW, manual is already big help!! Thanks.
 
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Old 11-24-14, 06:05 PM
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Some furnaces have a service switch that looks like a light switch. Others plug into an outlet. Just shut down power and then turn back on after a few seconds. What you can do so you won't have to run up into the attic is to bypass the thermostat. To do that use a short jumper wire such as a paper clip between the R and W terminals on the control board. That should start the ignition sequence. You will need to push the door switch in to get power to the furnace when the access panel is removed. Watch for this sequence: inducer starts up, pressure switch closes, ignitor glows, gas valve opens, ignition occurs, and blower comes on.
 
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Old 11-24-14, 06:24 PM
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Yea, furnace was moved from closet w/ switch to attic...just plugged into live outlet. Do I unplug stat connector @ control board or just back probe and jump R - W w/ connector still plugged in?...What will that do? Simulate heat setting on stat??
 
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Old 11-24-14, 06:27 PM
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You can leave the thermostat wires connected at control board terminals. Jumping R to W is bypassing the thermostat. 24V from the R terminal energizes W which is the heat relay. Another thing to do is to make sure the condensate drain system is not clogged or restricted. Once you get the flash code it will hopefully point to where to focus on the probable cause.
 
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Old 11-24-14, 06:38 PM
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Thanks for the tips!!! That should get me stated for tonight. I'll post back later as to results. If you think of anything else in the meantime, please post and I'll follow steps. BTW, if I recall, there were 2 or 3 small hoses going to or around inducer fan area connected to what must be other pressure / vac. sensors / switches. I'll have to look again.
 
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Old 11-24-14, 06:40 PM
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You have a two-stage furnace so you have two pressure switches. Make sure those hoses are clear and don't have any water in them or blockages.
 
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Old 11-24-14, 06:47 PM
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Thanks. Got to run to HD then will go over and start checking. I'll post back later w/ updates. Really appreciate the help!!
 
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Old 11-26-14, 03:22 AM
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Found problem. On wire diagram pg. 39 of install manual, the switch called "front cover pressure switch" with the gray wires that go to gas valve was full of water???? Any ideas?? Furnace is mounted horizontal and hose to switch is coming from bottom next to drain hose but switch is still mounted slightly above this level. Can switch be mounted higher to prevent this?? Found this by checking continuity of switch and sucking water into mouth (so nasty ) from hose!! Anyways, drained switch and pulled small vac. on switch to remove all water, remounted and connected switch and furnace fired up. Is this common? Install problem? How can I prevent from happening again? Name:  Goodman GMV95_1.jpg
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Old 11-26-14, 05:35 AM
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Glad to hear you found the issue. Be careful sucking on those hoses because the diaphragm is very thin and you can damage the pressure switch. The best way to handle the issue with water in the pressure switch hose is to make sure the entire drain system is maintained on a regular basis. Check the drain system configuration instructions starting on the bottom of page 20 in the installation manual. Make sure all of the hoses are connected and figured exactly as shown in the diagram on left column, page 21. Your photo doesn't shown the drain trap but that is one of the most important pieces of the condensate drain system. It needs to be cleaned out on a regular basis and primed with water to ensure proper draining. The collector box hose needs to be removed om a regular basis to make sure the collector box is draining. If you have a condensate pump that needs to be taken apart and cleaned on a regular basis as well. There should be no need to move the pressure switch higher.
 

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Old 11-26-14, 05:36 PM
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Hopefully the switches will be ok as I did blow and suck into them repeatedly probably harder than I should have to make sure they switching. If not, guess I'll be buying some new ones. Hopefully they are readily available. The drain system may be a problem after looking more closely at it. I may have to try and modify it somehow...not to easy though being horizontal in the attic. Although, this is the first time have had problem in 4-5 years of operation? AC usually runs June, July, Aug, and Sept and heat Nov, Dec, Jan, Feb, Mar each year. Anyways, seems to be working again. Guess I'll have to check more often. There are 2 air returns w/ filter grills in house that get new filters each season and the 1 good filter in the unit in the attic stays pretty clean so I don't get up there much to change. Will start going up there once a season now!! Thanks again for the help and the manual.
 
 

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