Goodman furnace won't ignite and it's cold outside.


  #1  
Old 01-12-10, 04:26 PM
T
Member
Thread Starter
Join Date: Jun 2009
Location: USA
Posts: 16
Upvotes: 0
Received 0 Upvotes on 0 Posts
Exclamation Goodman furnace won't ignite and it's cold outside.

I have a Goodman GMPN120-5 furnace. Tonight I noticed that our house was getting quite cold and found that the furnace was not kicking on. I power cycled the furnace and listened to it's cycle. The exhaust fan turned on (vents though a pvc pipe to the outside) and ran for around 3 minutes and then shut off. I noticed that the ignitor never glowed as it should. I didn't smell any gas. I noticed something that looks like it may be a flame detecting sensor which lies in front of one of the metal tubes where the flame develops. Anyway, I noticed it looks pretty caked up with soot.
I checked the computer board in the furnace and the diagnostic light blinks three times, pauses and then repeats with three blinks then pause and so on.
I don't recall ever replacing the ignitor. It doesn't appear to be defective from what I can see. If I knew what the three blinking red leds represents that would help.
Any other ideas I should try?
It's supposed to get down in the teens tonight, so I need to get this fixed quick!
thanks
 
  #2  
Old 01-12-10, 04:29 PM
S
Member
Join Date: Feb 2009
Location: pittsburgh pa
Posts: 121
Upvotes: 0
Received 0 Upvotes on 0 Posts
problem

on the furnace somewhere,usually the cover there should be info on what the 3 blinks means.you need to see what it sez and report back.u sure the ignitor does not glow?
 
  #3  
Old 01-12-10, 04:46 PM
T
Member
Thread Starter
Join Date: Jun 2009
Location: USA
Posts: 16
Upvotes: 0
Received 0 Upvotes on 0 Posts
Originally Posted by seabee570
on the furnace somewhere,usually the cover there should be info on what the 3 blinks means.you need to see what it sez and report back.u sure the ignitor does not glow?
ok, I found what the 3 blinks means - pressure switch failed to close. It says to check any of the following three things:
venter
pressure switch
vent blockage

my questions:
1. what is a venter?
2. where can I find the pressure switch and is there a way to test it?
3. how can I check and unblock the vent if necessary?
4. I assume the ignitor isn't glowing because the pressure switch is preventing it.
 
  #4  
Old 01-12-10, 04:59 PM
S
Member
Join Date: Feb 2009
Location: pittsburgh pa
Posts: 121
Upvotes: 0
Received 0 Upvotes on 0 Posts
Problem

DOES THE FURNACE VENT with pvc(plastic pipe?) the vent motor is a small motor that pushes the combustion products to the outside.it is a small motor,if the furnace is upflow,normally near top under the panel cover. you need to see if the ventor motor is runnign when thermostat is set to call for heat.if so,and you still get code,you need to check the hoses that go from vent motor to the furnace,pull off the hose,and check the opening going inot furnace.make sure it is clean,fully open.make sure there is no water in the hoses. do you have a condensate pump?if so,make sure that it is working and pumping properly.
FIRST OF ALL GO OUTSIDE TO WHERE THE FURNACE VENTS,AND CHECK AND SEE IF THE PIPE OR PIPES ARE OBSTRUCTED,POSSIBLY ICE...
 
  #5  
Old 01-12-10, 04:59 PM
T
Member
Thread Starter
Join Date: Jun 2009
Location: USA
Posts: 16
Upvotes: 0
Received 0 Upvotes on 0 Posts
I disconnected the vent pipe from the blower. The blower turned on and the ignitor started glowing. So it looks like the vent pipe is blocked. I can feel outside air blowing into the vent so I am not sure why it is being detected as blocked. Does this sound right or could it still be the pressure switch? I found the pressure switch now, but I'm not sure how to test it.
Also, how do I unblock the vent?
 
  #6  
Old 01-12-10, 05:02 PM
S
Member
Join Date: Feb 2009
Location: pittsburgh pa
Posts: 121
Upvotes: 0
Received 0 Upvotes on 0 Posts
Pipe

IF YOU DISCONNECTED THE VENT PIPE GOING TO THE OUTSIDE YOU CANNOT RUN THE FURNACE THIS WAY,YOU HAVE CARBON MONOXIDE DUMPING INTO YOU HOUSE.STOP.GO OUTSIDE AND CHECK THE VENT PIPE SHUT DOWN THE FURNACE AND PUT PIPE BACK TOGEHTER
 
  #7  
Old 01-12-10, 05:06 PM
S
Member
Join Date: Feb 2009
Location: pittsburgh pa
Posts: 121
Upvotes: 0
Received 0 Upvotes on 0 Posts
pipes

dou u have 2 pipes or 1 pipe? did you disconnect the exhaust,pipe leaving the vent motor? if so stop
 
  #8  
Old 01-12-10, 05:09 PM
S
Member
Join Date: Feb 2009
Location: pittsburgh pa
Posts: 121
Upvotes: 0
Received 0 Upvotes on 0 Posts
hello

u there hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
 
  #9  
Old 01-12-10, 05:10 PM
T
Member
Thread Starter
Join Date: Jun 2009
Location: USA
Posts: 16
Upvotes: 0
Received 0 Upvotes on 0 Posts
I only disconnected just until the ignitor started glowing and then I shut the furnace off and reconnected the vent. The gas never ignited.
Thanks for the caution though.
 
  #10  
Old 01-12-10, 05:11 PM
E
Banned. Rule And/Or Policy Violation
Join Date: May 2007
Location: Wisconsin
Posts: 7,826
Upvotes: 0
Received 1 Upvote on 1 Post
Originally Posted by Tmaxx
I disconnected the vent pipe from the blower. The blower turned on and the ignitor started glowing. So it looks like the vent pipe is blocked. I can feel outside air blowing into the vent so I am not sure why it is being detected as blocked. Does this sound right or could it still be the pressure switch? I found the pressure switch now, but I'm not sure how to test it.
Also, how do I unblock the vent?
Run a snake through it AND use a shop vac.

It is also possible I suppose that maybe nothing is in it and something in the venting through the furnace is so marginal that just the eensiest less restriction by having the extended length/elbows of the vent pipe off was able to give it like .01 more water column to get the pressure switch to clsoe/stay closed. Or, it's a coincidence, and may work sometimes also, with or without the ventpipe connected.
 
  #11  
Old 01-12-10, 05:16 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 4,469
Upvotes: 0
Received 1 Upvote on 1 Post
Originally Posted by Tmaxx
I noticed something that looks like it may be a flame detecting sensor which lies in front of one of the metal tubes where the flame develops. Anyway, I noticed it looks pretty caked up with soot.


Gas furnaces should not be making any soot. If it does, it indicates a significant hazard which will likely produce A LOT of carbon monoxide. Removing the vent pipe means that you are quite probably venting very dangerous combustion gasses into your house.

Also, a sooted heat exchanger will plug up the heat exchanger and cause the pressure switch to open and the burners to fail to work as you describe.

In short, you should leave the furnace off until it's been inspected and repaired by a competent repairman.

From your description, the furnace could easily be a lethal killer in it's current condition.
 
  #12  
Old 01-12-10, 05:21 PM
T
Member
Thread Starter
Join Date: Jun 2009
Location: USA
Posts: 16
Upvotes: 0
Received 0 Upvotes on 0 Posts
I removed the black flexible tube coming off the bottom of the vent pipe which runs vertical. The black tube comes off the bottom of the vent pipe and connects into what I believe is the condensate pump. Anyway, when I disconnected the black tube, there is a thick black sludge inside the opening. Is this normal or does this indicate a more significant problem?
 
  #13  
Old 01-12-10, 05:36 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 4,469
Upvotes: 0
Received 1 Upvote on 1 Post
Black sludge again strongly suggests a sooted heat exchanger which can be very dangerous because LARGE AMOUNTS of carbon monoxide would be produced to create the soot and by interfering with normal gas combustion.


Everything you have posted suggests a dangerous situation. Leave the furnace shut off until it's been inspected by a competent repairman.
 
  #14  
Old 01-12-10, 05:38 PM
T
Member
Thread Starter
Join Date: Jun 2009
Location: USA
Posts: 16
Upvotes: 0
Received 0 Upvotes on 0 Posts
Originally Posted by SeattlePioneer
Black sludge again strongly suggests a sooted heat exchanger which can be very dangerous because LARGE AMOUNTS of carbon monoxide would be produced to create the soot and by interfering with normal gas combustion.


Everything you have posted suggests a dangerous situation. Leave the furnace shut off until it's been inspected by a competent repairman.
Ok, sounds like a good plan. Thanks for everyone's help. I learned a few things along the way.
I'll post back when the repair guy figures out what's going on.
 
  #15  
Old 01-13-10, 05:55 PM
T
Member
Thread Starter
Join Date: Jun 2009
Location: USA
Posts: 16
Upvotes: 0
Received 0 Upvotes on 0 Posts
Smile Problem fixed...

Just following up on what the problem was here. I had my repair guy out today and he checked the pressure switch first. He unplugged the line from the blower and sucked on it until he heard the pressure switch trip. He plugged it back in and fired the furnace up. He said there must have been some blockage in the line to the pressure switch.
The furnace is working fine now.
thanks.
 
  #16  
Old 01-13-10, 06:48 PM
SeattlePioneer's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Jul 2007
Location: Seattle, Wa
Posts: 4,469
Upvotes: 0
Received 1 Upvote on 1 Post
I hope he checked to see where all that soot was coming from. If he didn't and the heat exchanger is sooted up, it'll be back as a problem.


Perhaps it was just some black mold growing in the furnace drainage system ----let's hope.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: