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i have a goodman gmp 075-3 gas furnace. i woke up this morning and it was 59 in here.not freezing but certainly cold enough for me. i went to the furnace and i am getting three blinks. it says pressure switch failed to close.im a carpenter by trade so im pretty handy but i have no idea what a pressure switch is or where it is located. can anybody help. i just bought this house a year and a half ago,the furnace is about two or three years old id guess. in the yerar and a half ive been here ive had to replace the flame sensor twice. now this.is this common for goodman because im not going through this two or three times a year. i will gladly share some of my knowledgeof carpentry for anyone interested, but right now can some one help?please?
 

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You should have a little hose coming off the inducer motor "little motor that starts first" going to the safety pressure switch make sure that hose is not leaking vacuum or is tight also it can be the safety switch itself they do go bad but sometimes it's simply the hose is loose try that and check back.
 
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UncleSam said:
You should have a little hose coming off the inducer motor "little motor that starts first" going to the safety pressure switch make sure that hose is not leaking vacuum or is tight also it can be the safety switch itself they do go bad but sometimes it's simply the hose is loose try that and check back.
well i checked the hose and its not leaking anyplace. any more suggestions? also any idea how much one of those safety switches runs? oh by the way thank you very much for trying to help me out. i really appreciate it
 

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Is the inducer housing a black painted one? If it is is there paint "peeling" off of it? Some of those were painted on the inside as well and the paint chips would get into the housing nipple and block air flow to the switch. Check your flue for any restrictions and you may also want to have the inducer motor itself checked with a magnahelic guage to make sure it is running at full rpm. Have found that to be more common than switches going bad. Also, if the furnace is only 3 yrs. old, many of those had a 5 yr. parts warranty (no labor) so check your paperwork that should be with your furnace.
 

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Unregistered said:
well i checked the hose and its not leaking anyplace. any more suggestions? also any idea how much one of those safety switches runs? oh by the way thank you very much for trying to help me out. i really appreciate it

To check to see if the switch is bad you can bypass it "for checking only do not run furnace with switch bypassed" I use a small wire with alligator clips on it and i plug it into both wires that plug into the switch if it runs like normal then you have a bad switch now sometimes these switches can have a bit of trash or something in them and if you suck and blow lightly into the vacuum hose it sometimes can dislodge it if that does not work then if by bypassing the switch the unit run ok then it's definitely the switch, check back after trying that.
 

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UncleSam said:
if that does not work then if by bypassing the switch the unit run ok then it's definitely the switch, check back after trying that.

Not all the time Sam. If the inducer isn't running full RPM or if there is restriction in the flue and not pulling the switch in on its own, by-passing the switch isn't really proving anything.
 

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HVAC Doc said:
Not all the time Sam. If the inducer isn't running full RPM or if there is restriction in the flue and not pulling the switch in on its own, by-passing the switch isn't really proving anything.

Doc, i do realize that if the inducer is not turning enough rpm it will kick out the heat also amoungst a few other things, i was just giving him a simple place to start, he has to start somewhere.
 
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well i tried by-passing the switch and it still doesnt run. i dont have access to one of those gadgets to check the rpms of the inducer. the inducer appears to be made of black plastic.i tried blowing into both ends of the little hose as well,and still nothing. any other suggestions fellas.the paperwork for the furnace is nowhere to be found. the lady i bought the house from had sears install the furnace, however she moved to texas and i dont know how to contact her.thanks for helping me out
 

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The unit does not do anything? or what does it do? does anything come on a run at all?
 
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no it doesnt do anything. it makes a little click up in the top circuit board like its gonna run but nothing happens. then the light starts blinking. i opened up the flue and its clear of debris. i dont know what to do next. if it was a piece of wood id cut into something, but im no furnace man thats for sure
 

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Is it a 3 pole pressure switch (3 leads)? If it is, you are going to have to jump the correct set of contacts as one set will be normally closed on start up and the other set will be open. Use an ohm meter to find out which set is which if it is a 3 pole. Good luck.

BTW I just checked on your furnace and it indeed had a 5 yr. parts warranty on it from the factory.
 
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no it only has two leads on it.i wonder if the warranty would still be good,i dont know if it is transferrable ornot but it would be worth looking into
 

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Your pressure switch will not keep the unit from not doing anything it would go through all the changes but when the switch did not make it would kick it back out, did you try turning off the power for a few seconds and turning it back on? You know you have a problem that could be many things and i am not there so i was just trying to keep it simple for you. If that unit is within the 5-years warranty call a Pro and let him check it out the parts should be in warranty if it's a Goodman you should only have to pay for a labor charge you don't have to say anything about rather you or someone else bought the furnace if it's still in warranty he will know by the serial # and that is all he needs to give the folks at the supply house.
 
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Discussion Starter #14
okay thanks alot for all your help. i really appreciate it
 
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