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I have a Lennox G43UF Series furnace. It is not blowing hot

I have a Lennox G43UF...
I have a Lennox G43UF Series furnace. It is not blowing hot air to the house. The LED#1 light is off and LED #2 is Slow Flash, which I understand to mean the combustion Air pressure switch is not open. What do I do?
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Answered in 24 minutes by:
10/1/2009
KenCan
KenCan, HVAC Technician
Category: HVAC
Satisfied Customers: 111
Experience: 20+ years experience, Nate certified, EPA certified, TX state license
Verified

Hello,

Do you know where the pressure switch is located on this furnace?

 

Thanks,

Ken

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Customer reply replied 8 years ago
Thank you for offering to help me. Yes, and I have my installation guide and manual to follow along. That is how I was able to provide this information. I found it on the trouble shooting section under the "Heating Sequence of Opertation" section.

Thank you for responding back.

 

Ken

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Customer reply replied 8 years ago
OK I have the pressure swith located.

Ok. What you will do not is find the rubber hose and remove off of the pressure switch and the other end where it connects to the ports on the long black box. You will want to look inside these ports for any debris. You will want to also see if you can blow into once you put hose back in. Make sure you do not blow into the pressure switch. After you do this you can put hoses back on and give a call for heat and see if unit will run.

 

Thanks,

Ken

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Customer reply replied 8 years ago
No luck. I have two rubber hoses. ONe red and one black. Both were clear of debris. The Combustion Air Inducer sounds like it has a hum coming it and the cylinder that connectis into it with copper wiring inside is extremely hot!

Ok. Have you ever seen your igniter glow yet?

 

Ken

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Customer reply replied 8 years ago
Is that the silver box that is on the top on the inside with a small glass opening? If yes, then the answer is no, there is no igniter glow. I have a honeywellVR8205 Gas Valve with on/off lever. I followed the directions to try to light the unit before but again, with no luck.

Yes this is where your igniter is. Are you ready for some more hands on?

 

Ken

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Customer reply replied 8 years ago
Yes I am

Ok. You will need to find the two wires that go to the pressure switch that you found earlier. Once you find these you will first need to shut the furnace off at the thermostat. Then you will remove these two wires. Next give a call for heat from the thermostat and be ready to jump these two wires together when your small inducer motor (just below your burner box) comes on. After these two wires are joined together you will look for the igniter to come on and the unit to fire off. After your furnace fires off shut down at the thermostat you will not need to let it run for more than a couple of seconds. We just want to see if it will fire off.

 

Thanks,

Ken

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You can use a metal paper clip to join the two steak ons together. Both wires will need to make contact after the inducer motor starts up.

 

Ken

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Customer reply replied 8 years ago

I'm sorry, I don't fully understand. I turned off the thermostat and removed the two wires. I'm not sure what you mean by jump the wires together. They have white plastic caps on them. Should I try to touch them together, or do you mean place them back on the switch when the motor comes on? should I remove the white caps from the wires? OK I just got your post about the paper clip. I'll try that

 

Customer reply replied 8 years ago
I'm sorry, I don't fully understand. I turned off the thermostat and removed the two wires. I'm not sure what you mean by jump the wires together. They have white plastic caps on them. Should I try to touch them together, or do you mean place them back on the switch when the motor comes on? should I remove the white caps from the wires?
Customer reply replied 8 years ago

The inducer motor is not starting up. It only hums, unless that is what it is suppose to do. I did use a paper clips to join the two wires and nothing happened.

 

If your indcuer motor is not starting up this is going to be your problem. What is the serial number of this furnace?

 

Thanks,

Ken

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Customer reply replied 8 years ago
S/N is 5906H43089. What should the inducer motor sound like when it is on? Does this have anything to do with the AC, as that was working fine a week ago?

Inducer motor has nothing to do with the AC. The purpose of the inducer motor is to pull the air through your heat exchanger and close the pressure switch. It should sound like a small fan and should be the first thing that comes on when you call for heat. The good news is this furnace has a 5 year on the parts and the inducer motor is one of those parts.Smile Don't forget to put both of your wires back on the pressure switch.

 

Thanks,

Ken

 

Positive Feedback is appreciated!!

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Customer reply replied 8 years ago
Thanks for your help! I'll have to call to have someone come out. I know I have to cover labor cost. About how many hours on average to replace an Inducer motor? I don't want to get ripped off.

SmileIf the technician has done this before it should not take more than 30 minutes to do. He is removing five 1/4 inch screws and putting a new gasket behind the inducer motor. You can call a couple of different contractors and tell them what you need and let them know that the furnace is under warranty and ask each one what they would charge for the installation of an inducer motor. This could save you some $$$

 

Thanks,

Ken

 

 

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You can put your zip code in this link for some contractors in your area.

 

http://www.lennox.com/residential/#

 

 

KenCan
KenCan, HVAC Technician
Category: HVAC
Satisfied Customers: 111
Experience: 20+ years experience, Nate certified, EPA certified, TX state license
Verified
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Category: HVAC
Satisfied Customers: 111
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Experience: 20+ years experience, Nate certified, EPA certified, TX state license

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