Furnace Codes

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  #1  
Old 11-05-02, 10:00 AM
Ken Roy
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Question Carrier Gas Furnace Codes

I have a Carrier Weather Maker 8000 Two-Speed gas furnace in a "New to me" house. I'm getting a code 32 error. The text for a code 32 states it could be:

"Low Heat Pressure, Draft Safeguard or Aux-Limit (Downflow only*) switch did not close or reopen."

The igniter glows bright orange, the gas comes on, the flame is blue across all burners, then it shuts down and starts flashing the code. It just started this last night and would fire up after the second try. It now will not fire up at all. Any suggestions?

Thanks,
Ken
 

Last edited by Ken Roy; 11-05-02 at 11:07 AM.
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  #2  
Old 11-12-02, 08:21 AM
Ken Roy
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Unhappy Update to the problem

I had a technician come out after the furnace would not come on at all. He replaced the old, dial thermostat and cleaned everything that the panel said the LED Code 32 could be. He tested the furnace and it worked fine. I come home it does the same thing, starts fine then shuts down. Sometimes it shuts down after a few seconds of the flame burning. Sometimes it shuts down after the burner has been going and the large fan starts to blow the heat through the ducts. Sometime it will try to start and will work fine after three attempts. I hate to have the tech come out and start swapping parts at $68/hour. Any suggestions?

Thanks,
Ken
 
  #3  
Old 11-12-02, 06:39 PM
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be sure

the flame sensor has a good ground. it may be dropping out. you did not say how old the unit is, flame sensor may need to be cleaned/replaced. this is generally the cause of what you describe, but i would look at the pressure switch as well. you will find a higher resistance (shown with a magnahelic guage) on the induced draft motor when the burners light than before they do. the switch may be getting weak, and dropping out, look closely at this as it would produce the fault code you are getting, whereas a flame sensor failure would generally produce an "ignition failure/lockout" code.
 
  #4  
Old 11-13-02, 08:10 AM
Ken Roy
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Draft Motor, Age, Pressure Switch

I think the furnace was installed around 1994. Here's the model # and serial #:

Model: 58TUA08014
Serial: 4994A06282

Maybe you can tell from these?

Let me see if I understand your last post. The draft motor is running when the burners light. Then the draft motor starts to drag (higher resistance) and the pressure switch picks up the change in airflow and opens the switch, which shuts down the burner. Is this what might me happening? Forgive my ignorance but I'm trying to learn how these things work as we go.

I did check the voltage to the motors and the main board. I'll check the voltage and ground on the flame sensor.

After looking at the schematic on the door, I don't think this unit has the optional Aux-Limit switch. Does this sound right?

Thanks for the help, I appreciate it.
 
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Old 11-16-02, 10:48 AM
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age

the third and forth digits in the serial indicate year on manufacture. In your case 94 as in 1994.

The aux limit is for downflow models. Down flow means cold air return to the top of the furnace and hot air leaves the bottom, up flow would be the opposite.

Check the switch as hvac4u suggested, but your draft motor could also be about to die. If it's slowing down after the burners light there-by reducing air flow the switch would open.

The tech you had over should have cycled the unit a number of times to ensure it lights each time and after the thing heats up.
 
  #6  
Old 11-18-02, 08:51 AM
Ken Roy
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Still Watching

Thanks for the help.

I think I'm down to the draft motor or the pressure switch. The code is not coming up consistently now so I'm going to wait before I have a tech come out with a magnahelic gauge. I climbed up on the roof and checked to make sure the vent is not plugged. I can manually cycle the switch my lightly sucking on it.

I don't really know how to test the draft motor other than seeing if it starts or stops. Any suggestions?

Thanks,
Ken
 
  #7  
Old 11-18-02, 05:50 PM
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Well one way to test the draft motor is by useing an amp meter to check the amperage draw of the motor. An amperage draw at the high end of what the motor is rated would indicate a failing motor.

The fact that you can cycle the switch may indicate that it isn't the problem.

The fact that the code isn't coming up consistantly now would lead me in the direction of the draft motor.

I wonder if hvac4u would concur.
 
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Old 11-18-02, 06:22 PM
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this is tough one

mfr date also says 49th week of 94, first 2 are week. jaredsdad has a point with the amp draw, but honestly if it was bad it may be too minimal to tell. the board only knows what the switch tells it, and there fore could be either bad motor, switch working fine or bad switch giving wrong signal of fan failure. in my experience, if flue is clear, i have not seen the motor drop vent draw below psi switch cutoff. it is always the switch. just my 2 cents, wish i were there
 
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Old 11-19-02, 05:06 PM
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Yeah, I'm leaning more towards the switch. I only mentioned taking amperage readings as a way to check the motor.

Why not go ahead and change the switch and see if it cures the problem? Can't cost much more than 30 bucks.
 
  #10  
Old 11-19-02, 05:26 PM
rclhvac
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Carrier & Bryant had problems with these circuit boards- you need the newest board. I've replaced many of these with the same symptoms. The relay for the induer motor drops out giving you the pressure switch failure.
 
  #11  
Old 11-20-02, 07:53 AM
Ken Roy
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Question Carrier Parts

Well, I guess the only way to test a solid-state circuit board is to swap it out. Does anyone know where I can purchase Carrier parts online? I called a local distributor and they only sell to HVAC techs.

Thanks for the continued help.

Ken
 
  #12  
Old 11-20-02, 02:37 PM
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To check if the board is dropping the inducer motor, just watch the furnace. If the inducer drops out just before the gas valve shuts then there's your answer.

http://www.e-johnstonesupply.com may let you order online and ship to your house. I personally don't like the site's set up very much.
 
  #13  
Old 11-22-02, 12:23 PM
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I had a similar problem with a Carrier of the same vintage. Had to replace the board. I believe it was around 150 for mine at the local Carrier Dealer. Not too bad considering the service call I saved. A couple hot spots were visible on the board.
 
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