Fixed pressure switch open light flashing now will not light??


  #1  
Old 02-01-16, 12:49 PM
S
Member
Thread Starter
Join Date: Feb 2016
Location: USA
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Fixed pressure switch open light flashing now will not light??

Hi,
So I have Amana ahm95 furnace, the furnace light was flashing 3 times which the manual says that the pressure switch is open. So I cleaned the exhaust pipe and drained water from it, cleaned nipple on inducer and coil cover, checked tubing to pressure switch, blew into pressure switch and can hear both switch open and close, took the inducer off checked for obstructions. After all that the light stopped flashing but now the ignition lights then nothing happens it try's 3 times then locks out😣. If I use a paper clip and bypass the pressure switch that is connected to the coil cover it will light up and works perfect. So now I am not sure where to go from here? If anyone has any ideas I would really appreciate it. Cheers
 
  #2  
Old 02-01-16, 01:54 PM
S
Member
Join Date: Feb 2014
Location: USA
Posts: 2,101
Received 0 Likes on 0 Posts
That furnace has 2 pressure switches have you checked both of them?
 
  #3  
Old 02-01-16, 02:08 PM
S
Member
Thread Starter
Join Date: Feb 2016
Location: USA
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
I checked both and they seem to be fine, the one that connects to the gas pump if I bypass it the furnace works fine but when connected like normal no lights flashing, ignition works just no gas
 
  #4  
Old 02-01-16, 03:12 PM
S
Member
Join Date: Feb 2014
Location: USA
Posts: 2,101
Received 0 Likes on 0 Posts
Gas pump? Do you mean gas valve?
 
  #5  
Old 02-01-16, 03:25 PM
S
Member
Thread Starter
Join Date: Feb 2016
Location: USA
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Sorry I meant the gas valve. I have cleaned the ignition sensor, the inducer is working fine, the pressure switches both work, it just won't fire up after the ignighter lights up
 
  #6  
Old 02-01-16, 03:39 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 71,100
Received 3,196 Likes on 2,871 Posts
Welcome to the forums.

I'm on the road and didn't look up your furnace yet but try removing the large nylon plug on the control board a few times. Those pins can get corroded. Reconnecting it several times can clean corrosion.
 
  #7  
Old 02-01-16, 08:26 PM
S
Member
Thread Starter
Join Date: Feb 2016
Location: USA
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Hi Pete,
Thanks for responding👍 I tried taking it off and on a few times but no go, the connection looks pretty good. The thing is it will run if I bypass the pressure switch that is connected to the gas valve but when I connect it to the pressure switch it won't fire up. The pressure switches are both OK I have alternated jumpers cables on the pressure switch and it starts up even when alternating tubes to see what the pressure is like on each nipple, but when they are both connected the igniter lights but no gas to fire up by, it try's 3 times then locks out. So I have no idea where to go from here. The inducer seems to be running fine as there is no light flashing now, the blower runs when the furnace fires up, cleaned the nipples and tubing, blew the water caught in exhaust vent out with a leaf blower. So I am totally open to any ideas you might have. Cheers Simon
 
  #8  
Old 02-02-16, 12:14 AM
S
Member
Thread Starter
Join Date: Feb 2016
Location: USA
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
So now I am totally confused it seems the light on the circuit board is not showing that there is still a pressure switch problem🤔 Does that mean I need a new circuit board?
 
  #9  
Old 02-02-16, 01:02 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 71,100
Received 3,196 Likes on 2,871 Posts
IF the igniter heats up then that means the pressure switch has proven and is ok. The igniter will NOT come on if the pressure switch circuit is not ok.

You need to check the gas valve for 24vac. That 24vac will only be measurable at the gas valve for a few seconds. It turns on just as the igniter turns off. If the burner lights the voltage will stay at 24vac and keep the gas valve open.

If the burner doesn't light..... the board goes into temporary lockout and tries the cycle again until it reaches full lockout.

If you have the 24vac present then the gas valve is defective.
If the 24vac is not present then the control board has a problem.
 
  #10  
Old 02-02-16, 01:02 PM
S
Member
Thread Starter
Join Date: Feb 2016
Location: USA
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Hi Pete,
So I retested the pressure switches they are working fine,and I tested the gas valve and the circuit board all seem to be working, so I pulled the tube of the coil cover that runs to the pressure switch and sucked on it while the igniter was glowing and it started up. I have taken that cover of before and it was clear of debris, so does that mean that there is something wrong with the condenser or is it the draft inducer not creating enough to vacuum?
 
  #11  
Old 02-02-16, 06:48 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 71,100
Received 3,196 Likes on 2,871 Posts
sucked on it while the igniter was glowing and it started up.
I assume you mean the burner started up.

I'm completely at a loss. Your furnace works backwards from every other furnace I've worked on. If you pull the pressure switch hose off, the pressure switch should open and the igniter should turn off. When you see the igniter glowing it's supposed to mean the pressure switch is satisfied.

I cannot find your exact manual..... see if this is the same furnace as yours.
YORK TM9V*C INSTALLATION MANUAL Pdf Download.
 
  #12  
Old 02-03-16, 02:27 AM
S
Member
Thread Starter
Join Date: Feb 2016
Location: USA
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Hi Pete,
So it's weird the fault light will flash if I take the hose of the top pressure switch but if I do the same to the bottom pressure switch it doesn't flash?? I tested the voltage to the draft inducer and it was 120 at the circuit board and at the connection wires for the inducer. I also pulled the inducer out to see if seal was ok and if there was a crack or something I missed it all looked pretty good. I even got a cotton ball and put it on the end of the pressure switch tube connected to the coil cover and there is suction. So all I can think is the inducer is not spinning fast enough to create the right amount of suction. I don't have a manometer to check the vacuum that the inducer makes, so I was just going to buy a new inducer and see what happens, unless you have a better idea??
 
  #13  
Old 02-03-16, 06:59 PM
S
Member
Thread Starter
Join Date: Feb 2016
Location: USA
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
So I bought a new inducer and circuit board and install them both and it is exactly the same, igniter lights but the burner doesn't, it has this weird square tubing so I thought I would replace that too. I then switched the nipples tubes to opposite pressure switches and the burner start working. So my question is. Does the tubing have to go to specific pressure switch? If I remove the tubing from either switch it faults out like it is supposed to
 
  #14  
Old 02-04-16, 12:30 AM
S
Member
Thread Starter
Join Date: Feb 2016
Location: USA
Posts: 13
Likes: 0
Received 0 Likes on 0 Posts
Sorry Pete, I hadn't heard from you and wasn't sure if anyone was checking threads and was looking for an answer about the tubing. I have a manual and it is not the correct way for the tubing to go, but I have literally tried everything I can think of. Not sure where to go from here 😔 The totally bizarre thing is that the suction from the coil cover nipple will open the top pressure switch but add 4 inches further distance and it won't, and I have tried 2 different pressure switches on the bottom and it's the same. So I suppose my next step will have to be call a technician but not sure what he could say as I have replaced basically everything except the gas valve and it works fine if the vacuum is closing the bottom pressure switch. Anyway thanks for your help
 
 

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