The Induced Draft Blower starts to run but there is no furnace operation. The Integrated control module diagnostic LED is flashing 3 flashes. The possible causes listed in the manual say:
1. Pressure switch hose blocked, pinched or connected improperly.
(I took of the front cover of the furnace and looked at this rubber Pressure switch hose and it looks fine to me)
2. Blocked flue and/or inlet air pipe, blocked drain system, or weak induced draft blower.
(I went outside and checked the flue and inlet and they both look fine, with no visible blockage. I inspected the drain system that comes out of the side of the furnace and that also looks fine, with no visible problems. The Induced Draft Blower sounds fine when it kicks on too, sounds strong with no audible odd or weird noises eminating from it.
3. Incorrect pressure switch setpoint or malfunctioning switch contacts.
(I don't have any idea how the pressure switch setpoint could be off since I have never adjusted it and I have no idea how to adjust it or what would even be a proper adjustment of it. As far as malfunctioning switch contacts, I don't know why they'd be malfunctioning, the furnace is in a clean dry furnace room with little or no dust and very little moisture. Visibly, all of the contacts look great.
4. Loose or improperly connected wiring.
(I don't know how any of the wiring could be loose or improperly connected because the furnace has run for 3 years with no problems)
This problem all started about 4 weeks ago when the furnace would run, but never for long enough to get the house warmed up to the adjusted thermostat tempurature of 69 degrees. It was keeping the house heated at around 65 degrees at that time. Now it has entirely stopped heating whatsoever, with the blower turning on and then the Integrated control module LED goes from steady on to THREE quick flashes, meaning that there is a problem. The flames never ignite and then the blower eventually turns off.
I pulled the drain tubing from the trap to see if any water is being held back. I blew into it and it seemed clear, although the trap is filled with water, but it looks like it's supposed to be because the trap drains at the top.
I also disconnected the pressure switch tubing at the pressure switch and by blew through it slightly to see if any debris was blocking the port. It seemed clear too.
The gas flow is definintely on to the furnace and I have just recently installed a new filter.
Any help would be greatly appreciated, I'm layed off and I really don't want to pay for a service call here.
For anyone who finds this question in the future - It's the condensate drain hose for the heat exchanger.
Get a bucket and some towels handy and unplug the lowermost flexible rubber hose - if you do this right after the furnace has stopped, water will come gushing out. Mine was continually plugging up causing my furnace to stop, like yours - the L shaped plastic tube that dips into the drain trap on the outside of the unit (the thing filled with water) was too close to the bottom of the trap. I took it out, shortened it by 1/2 an inch (keep the same bevel that's on there!) and I haven't had a problem since. Blowing out the line would only hold things off for a few weeks before it started acting up again.
Cost me $90 for a service call the first time since visually it looks fine and I checked the upper hoses that go to the pressure switch :)
Learn from my service call!
Take the hose connected to the pressure off the heat exchanger end and turn unit on and **** on the hose and make a vacuum to the pressure to make it connect if the unit starts the vacuum switch could be getting weak and needs changed
Remove the rubber vacuum hose and make sure the hose is clear. Then stick a thin wire down the fitting of the heat exchanger and dislodge anything that may be blocking it. After i did this, I reconnected the hose, and the furnace fired up like it should. I talked to my service guy shortly after. He says that Goodman painted the inside of the motor and after a couples of years the paint flakes off and clogs the opening. Just saved myself probably $150. To everyone who posted solutions, thanks for the help.
Also check to see if hose from bellow switch to draft inducer has water inside. if hose is to long can trap condensate
Just a tip: The two drum-shaped sensors in my Goodman GMS9 can be checked with even the cheapest digital multimeter (<<$20USD) and while supplying a 'mouth vacuum' check the resistance while measuring at the two electrical terminals.
One of mine measures ~10 Ohms, the other measures a flaky 50-600+ ohms and the control board doesn't seem to care about the difference.
The control board is likely a much higher value of impedance so if they are contacting at all, it is apparently enough.
Our problem is related to something else, not the vacuum sensors.
SOURCE: How to manually relight a
You should NEVER attempt to relight manually this furnace. Serious burns could be the result. This furnace has an electronic ignition and should light by itself. If it does not light you may have a bad ignitor. These are usually around 30-50 US dollars.
SOURCE: need help with a goodman gmt070 furnace
it may be clogged at the barbed fitting on the induced draft motor where the pressuer switch tubing connects. take a paper clip and **** it out make sure you can stick it thru freely till you can feel the Inducer wheel then reconnect and try again.
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