Comfortmaker Gas furnace not working
#1
11-17-14, 05:03 PM
Comfortmaker Gas furnace not working
Hello, my family bought an old house and we know nothing about this old furnace series. So here is the issue. Everything works fine last winter. However, this year, the furnace sometimes does not work when I use the thermostat call for heat. My current solution is reset the thermostat and call for heat numerous times until it ignite. So today I went downstairs and checked the furnace. Its Comfortmaker Model number N9MPD075F12A2 and I will attach a picture of the actual thing.
When I call for heat, the furnace starts working and making sounds for a long time(without ignite), and the pipe which from the furnace and going outside has water running sound in it. If I'm lucky the furnace will ignite after a few minutes. If not, the green light will flash 3 times
The thing on the bottom left corner is a pump for water going to the drain and the white pipe on the left side is going outside the house.
Thank you very much
When I call for heat, the furnace starts working and making sounds for a long time(without ignite), and the pipe which from the furnace and going outside has water running sound in it. If I'm lucky the furnace will ignite after a few minutes. If not, the green light will flash 3 times
The thing on the bottom left corner is a pump for water going to the drain and the white pipe on the left side is going outside the house.
Thank you very much
#2
11-17-14, 05:24 PM
Member
Welcome to the forum!! Here is a link to two manuals that will provide an excellent understanding of your furnace:
http://www.havenhomeclimatecare.ca/w...rite-c9mpd.pdf
http://icpindexing.toddsit.com/docum...4008200102.pdf
To start with I suggest making sure that condensate drain system is cleaned out and free flowing.
That includes a trap, hoses and drain pipes as well as the condensate pump. A clogged drain system can cause the problem you are having.
The attached photo shows two hoses (marked with broken white line).
http://www.havenhomeclimatecare.ca/w...rite-c9mpd.pdf
http://icpindexing.toddsit.com/docum...4008200102.pdf
To start with I suggest making sure that condensate drain system is cleaned out and free flowing.
That includes a trap, hoses and drain pipes as well as the condensate pump. A clogged drain system can cause the problem you are having.
The attached photo shows two hoses (marked with broken white line).
Last edited by firedawgsatx; 11-17-14 at 05:43 PM.
#3
11-17-14, 05:49 PM
Thanks for the welcome
I found all the parts you mentioned and i guess i ll just add water to the pump box to see if its working properly. I also did some research , some people say there might be clog in the PVC pipe that cause the problem too ?
I found all the parts you mentioned and i guess i ll just add water to the pump box to see if its working properly. I also did some research , some people say there might be clog in the PVC pipe that cause the problem too ?
#4
11-17-14, 06:08 PM
Member
Yes, it is possible. It could be a blockage/restriction in the air intake pipe or the vent pipe. There are several things that could cause the issue. One thing I suggest is to remove the hose from the pressure switch and make sure it is not full of water. Make sure the hose is clear end to end. Where the hose attaches to the inducer motor there is a port that gets full of crud and prevents the pressure switch from closing. You can use a small drill bit or opened paper clip to ream it out ensuring it is clear all the way through. The pressure switch is the component shown center bottom in the photo attached earlier.
#6
11-23-14, 07:37 PM
Hi, its been a while. Today i had time to check for exhaust pipe , waste water, fan and pump , everything seems fine. and i tried to use the door switch to test it twice and it works fine. still haven't locate the defect part. Do you have any other suggestions? and just wondering how to check for air intake? should i put my hand under the pipe to feel if there's air blowing before ignition ? because i don't think i can easily take the pipe done and check. Unless theres connection issue with pressure break, it seems working fine too.
#7
11-23-14, 07:56 PM
Member
Are you still getting the 3 flash code from the gas valve? Did you check the pipe that brings in air from the outside to make sure there are no blockages/restrictions inside. If the two pvc pipes have a horizontal run the they need to slope back toward the furnace 1/4" for every foot. And there can't be any sags in the pipe where condensate can collect and prevent air movement.
#8
11-24-14, 04:34 PM
Yeah still getting the 3 flash code. I did check outside. everything seems fine. I can feel some intake air pressure when i put my hand under the pipe. and both pipes do fulfill the 1/4 requirement. Today, i use the door switch again to test, because its not working again. First, the fan starts running and the ignition stick starts glowing. However, after 5 seconds , the ignition fails. I retry for 5 times. Then somehow the ignition is successful and everything runs normal again. This might be the reason why I can just reset the thermostat multiple times and eventually it will starts running.
#9
11-24-14, 04:48 PM
Member
Please post the number on the gas valve. When the igniter starts glowing do you hear a click inside the gas valve. Can you smell gas when the igniter is on? I suggest you remove all of the connectors from the gas valve and the control board and make sure none of the pins in the connectors are sticking further out or pushed in more than the others. Look for corrosion on the connectors. Then make sure the connectors are fully seated when you re-connect them. Before you call for heat is the gas valve showing the green "heartbeat" light?
Last edited by firedawgsatx; 11-24-14 at 05:12 PM.
#10
11-24-14, 06:14 PM
I do hear a click sound somewhere when igniter starts and also hear something when igniter shuts down for no reason. and i didnt smell any gas through the whole time. Is it possible its the connection issue of igniter or pressure break? because everything is fine when its running. everything is fine before the igniter fails, green light all along or kinda flash in a none sequential way.
#11
11-24-14, 06:22 PM
Member
A 3-flash code points to the pressure switch opening when it should be closed. Do you have a voltmeter to check for 24V at gas valve and at control board to see if the voltage is dropping out. As a test, bypass the thermostat by using a small jumper wire between R and W terminals at the control board. You will need to push the door switch in to start the ignition sequence.
#13
11-24-14, 06:33 PM
Member
Since you checked the most likely physical causes you have done about all you can without test equipment. I suggest you use the handle of a screwdriver to tap on the pressure switch to see if that causes a change in operation.
#14
11-24-14, 06:39 PM
Got it . i was just trying to do something cuz the furnace is not responding again. So i reset the thermostat again and headed downstairs. just when i was about to open the the lid , it starts running again. the annoying part is that everything will act normal even if you force a shut down, it will act normal in hours if there is a successful run within a time period. it makes it hard to detect the problem.
#15
11-24-14, 06:56 PM
Member
Those intermittent problems are the most difficult to diagnose. A pressure switch code can even be caused by wind. Sometimes the condensate drain clogs up a little and causes the control board to throw a 3-flash code. Once the condensate starts flowing the system starts operating properly again.
