Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 10-01-2008, 07:33 PM   #1
Newbie
 
Join Date: Oct 2008
Posts: 6
Share |
Default

Help...Furnance not working


Hi all...

I just bought this house, and when we have the house inspection the furnace and everything works perfectly. Well, we just close the deal last week and today's a chilly day in Michigan, so we tried to turn on the heat and it's not working.

The blower works, but there's no ignition. I tried to troubleshoot the three blinks, according to the diagnostic chart but still couldn't figure out what is wrong with it. It's a Comfort Maker, Model: N8MPN100F14A1, built July, 2003.

Please help guys...

Thank you in advance.

solitaryman is offline   Reply With Quote
Old 10-01-2008, 07:55 PM   #2
Electrician
 
SD515's Avatar
 
Join Date: Aug 2008
Location: Near Jackson Michigan Area
Posts: 1,450
Default

Help...Furnance not working


There should be a label somewhere on the machine that says what the code 3 means. Can you post what that says.

Also, describe what happens when it tries to startup.

What kind of fuel does it burn?

__________________
Kyle

Just because you can, doesn't always mean you should

Last edited by SD515; 10-01-2008 at 07:58 PM.
SD515 is offline   Reply With Quote
Old 10-01-2008, 08:28 PM   #3
Newbie
 
Join Date: Oct 2008
Posts: 6
Default

Help...Furnance not working


Quote:
Originally Posted by SD515 View Post
There should be a label somewhere on the machine that says what the code 3 means. Can you post what that says.

Also, describe what happens when it tries to startup.

What kind of fuel does it burn?
It says, it's a pressure switch? But where is the pressure switch? It doesnt start up, I dont even hear or smell any gas? Could it be that my gas line is not open? Or clogg?
solitaryman is offline   Reply With Quote
Old 10-01-2008, 09:24 PM   #4
Member
 
Join Date: Jan 2007
Posts: 1,782
Default

Help...Furnance not working


Quote:
Originally Posted by solitaryman View Post
It says, it's a pressure switch? But where is the pressure switch? It doesnt start up, I dont even hear or smell any gas? Could it be that my gas line is not open? Or clogg?
Make sure your gas shutoff valve is turned on.
handy man88 is offline   Reply With Quote
Old 10-01-2008, 09:30 PM   #5
Electrician
 
SD515's Avatar
 
Join Date: Aug 2008
Location: Near Jackson Michigan Area
Posts: 1,450
Default

Help...Furnance not working


Make sure the gas is on. The gas piping going into the furnace should have shut off valve. If the handle is 90 degrees to the pipe, it's off. Parallel to the pipe is on. Also, on top of the gas valve in the furnace, there may be an on/off switch, which also needs to be on. Most times it's turned on at installation, and left on, so all you need to do is check it. Neither of these have anything to do with a pressure switch having a problem. The furnace hasn't gotten to the point of opening the gas valve yet, but you do need them on anyways.

Now, the pressure switch. It's usually mounted in the burner compartment somewhere, usually metal (silver, about 2-1/2" to 3" in diameter, 1/2"thick) or plastic (black, about 1-1/2" to 2" dia, 3/4" thick...like the size of a huge Oreo cookie). Either style will have 2 wires and 1 or 2 hoses connected to it coming from the draft inducer motor (chimney vent motor) or the exhaust vent piping system (inside the furnace). The hose(s) may have a cut or hole in it, may be plugged, or the ports of the sw or motor may be plugged or cracked/broken. DO NOT BLOW INTO THE PRESSURE SWITCH. It has a thin diaphragm in it that can be damaged very easily from too much pressure. Most of the fixes I've done involving a pressure switch have required that the switch be replaced.

The sequence of operation:

Upon call for heat, the furnace 'looks' at the pressure switch to see if it's open, if so it starts the draft inducer motor. It goes back in a second or two and 'looks' again to see if it's now closed. If so, it proceeds to ignition sequence. (In your furnace, I think you have what's called 'Hot Surface Ignition'...it's a igniter that glows when it receives 120V and lights the gas)

Ignition sequence: Sends 120V to igniter. If igniter is intact and working, it will glow. A few seconds later, the gas valve opens and gas is shot into the burner venturi nozzles and ignites. A flame sensor at the opposite end from the igniter senses the flame and 'tells' the computer flame is present and shut the igniter off. After a short while, the main blower will start, to distribute the warm air through the house. Fire will burn until the t-stat 'tells' the furnace room temperature has been reached. The computer will shut the gas valve and the fire goes out. The blower will continue to run for a predetermined amount of time.

All that said...Pressure switches usually fail to close, hence you may hear the inducer motor run, but the furnace never gets to the ignition sequence. Pressure switches can't be 'bypassed' by just hooking the wires together, because the switch first has to be open, then closed. During testing they can be 'tricked or bypassed' to verify that's the problem, but you have to be right there doing it at every startup.

Again, it could be a small piece of debris in the hose or one of the ports, or a crack somewhere, etc. If you check the ports and hose and still can't get it to work, you should consider having a technician look at it.
__________________
Kyle

Just because you can, doesn't always mean you should
SD515 is offline   Reply With Quote
Old 10-02-2008, 07:34 PM   #6
Newbie
 
Join Date: Oct 2008
Posts: 6
Default

Help...Furnance not working


Thank you SD515. But I still cannot get it to work. I guess it's time for me to call in a HVAC tech. I have a friend of mine who is an electrician check all the wire and it all works.
solitaryman is offline   Reply With Quote
Old 10-02-2008, 11:08 PM   #7
Member
 
hvaclover's Avatar
 
Join Date: Oct 2008
Location: Suburbs of Detroit Mi
Posts: 3,704
Default

Help...Furnance not working


There is a short length of rubber tubing that goes toa round plastic part.

That is the pressure switch. Pull the tube off and blow thru it. It might be filled with water. That will stop the furnace from working.
__________________
Just slow, not stupid.
hvaclover is offline   Reply With Quote
Old 10-03-2008, 05:21 AM   #8
Member
 
1610 CUB's Avatar
 
Join Date: Jul 2008
Location: Keokuk,Iowa
Posts: 209
Default

Help...Furnance not working


If you just mover in is your gas meter unlocked?
1610 CUB is offline   Reply With Quote
Old 10-04-2008, 07:43 PM   #9
Newbie
 
Join Date: Oct 2008
Posts: 6
Default

Help...Furnance not working


The gas is on. My hotwater heater works.

Update: I just replaced the ignitor glow bar and it doesnt work. I still get 3 blinks, which is the pressure switch fault.
solitaryman is offline   Reply With Quote
Old 10-04-2008, 08:03 PM   #10
Member
 
Join Date: Sep 2008
Location: Portland, OR
Posts: 1,186
Default

Help...Furnance not working


Call the previous owner. They might know something.

Also if they did a house inspection and it passed and now the furnace isn't working???? Not much of an inspection. I would be rattling some cages.
Marvin Gardens is offline   Reply With Quote
Old 10-04-2008, 08:06 PM   #11
Newbie
 
Join Date: Oct 2008
Posts: 6
Default

Help...Furnance not working


Quote:
Originally Posted by Marvin Gardens View Post
Call the previous owner. They might know something.

Also if they did a house inspection and it passed and now the furnace isn't working???? Not much of an inspection. I would be rattling some cages.
The house is a bank own property that I bought it from. I have a property inspection done before making an offer, and during the time it works fine. The temp are at 110 at the second story.
solitaryman is offline   Reply With Quote
Old 10-04-2008, 08:07 PM   #12
Newbie
 
Join Date: Oct 2008
Posts: 6
Default

Help...Furnance not working


Does any one know what are the fees of a HVAC?
solitaryman is offline   Reply With Quote
Old 11-26-2008, 10:55 AM   #13
Newbie
 
Join Date: Nov 2008
Posts: 2
Default

Help...Furnance not working


hi did any one find this problem ? i know it maybe late but i have the same problem and the tech said it is the circuit board and it is around $400 please let me know if he is right and it is the right price it well cost me over $500 to fix it thanks
mastrix786 is offline   Reply With Quote
Old 11-26-2008, 11:29 AM   #14
Member
 
hvaclover's Avatar
 
Join Date: Oct 2008
Location: Suburbs of Detroit Mi
Posts: 3,704
Default

Help...Furnance not working


Quote:
Originally Posted by mastrix786 View Post
hi did any one find this problem ? i know it maybe late but i have the same problem and the tech said it is the circuit board and it is around $400 please let me know if he is right and it is the right price it well cost me over $500 to fix it thanks

Don't know where you are but that would be the low end in my part of the country.
__________________
Just slow, not stupid.
hvaclover is offline   Reply With Quote
Old 11-26-2008, 12:48 PM   #15
Newbie
 
Join Date: Nov 2008
Posts: 2
Default

Help...Furnance not working


i live in Virginia

mastrix786 is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Two switch in one box: only one working jdtsmith Electrical 12 09-29-2008 01:32 PM
Inside Fan not working BenH HVAC 20 07-08-2008 06:10 AM
Working with granite... SDeeter19464 Remodeling 5 06-14-2008 05:51 AM
GE fridge evaporator fan change and still not working Trish Appliances 2 03-30-2008 01:47 PM
Furnance burner won't stay on. 2007ken HVAC 11 03-03-2008 11:29 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.