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 Repairing and Servicing Lennox Products
 Repairing / Servicing Lennox Gas Furnaces
 G71MPP error code 291
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webster

3 Posts

Posted - 03/07/2009 :  6:25:06 PM  Show Profile  Reply with Quote
Hi new member here and hoping someone can explain what this code means?
First: The installed equipment is as follows and less than a year old.

1. G71MPP Heater Propane Gas
2. Thermostat 7000 series ComfortSense Model L7742U
3. Evaporator CR33 series
4. Heat Pump Merit 13HPX single stage

The unit heater fails on code 291 and as done so many times and the only way to restart is to cycle the electrical, at this point the unit will run just fine. My dealer and tech. person has been out three times and has not resolved the problem and my concerns with his ability to repair the unit are not good.
The Code 291 according to the book states Restricted airflow-available CFM below min.firing rate

The problem happens in the Morn. Heat pump runs for about 10 min can't bring up temp. fast enough pump shuts down, heater at this point comes on or fails to start and runs the code. out side temp between 35 and 40.

Thanks

slctech

2085 Posts

Posted - 03/08/2009 :  10:01:23 AM  Show Profile  Reply with Quote
To help narrow this down for me, I need you to go to your furnace and open up the bottom panel to access the main control board. On the main control board is that alpha/numeric LED light. Next to the light is the recall button. You will need to make sure your thermostat is in the OFF position for NO call for either heat or cool.
You will need to manually hold down the panel/door switch that de-energizes the furnace when you removed the panel to access the control board, so you have power to the board. At the same time you will find a small RECALL push-button next to the diagnostic LED. Press and hold down this button until you see an "E" on the diagnostic LED. When you see the "E" let go off the push-button and make note of the stored codes. What you are doing is accessing the error memory and the last TEN failure codes are stored for immediate access.
Once you have all the codes written down, just let go of the door/panel switch to kill power to the furnace and replace the doors.

Let us know what other codes you have. There are manufacture bulletins concerning the 291 code in conjunction with other codes that can be remedied, if in fact you are in the same situation. Most of it has to do with early versions of the control board. Lennox has upgraded the programming and is offering a newer control board fix, if you fall in this category.

Also, curious if the installing company has any static pressure readings recorded to allow for proper adjustment of the system? There may not be an issue with your furnace at all, but restrictive duct work, etc.

Here is the service manual for the G71...see table 25 on page 25 for specific instructions on pulling the past codes.
http://tech.lennoxintl.com/PDFs/0804c.pdf

Here is the bulletin concerning the ramping profile of the G71. I would have your technician verify that the system is properly set-up for dual fuel and that your control board is the updated version. This is the most common issue if you have an error code 311 in conjunction with error code 291.
http://tech.lennoxintl.com/PDFs/0812.pdf



As a Lennox Technician I feel basic repairs and maintenance can be performed by the homeowner. But I highly suggest that periodic maintenance should be made by a certified licensed technician. You should contact your local Lennox technician for any repairs or issues that are outside your comfort zone. Property damage, personal injury, and death can occur from improperly repaired or maintained systems. Replacing a part doesn't always resolve the issue that caused the part to fail!
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webster

3 Posts

Posted - 03/08/2009 :  3:00:02 PM  Show Profile  Reply with Quote
Hi slctech thanks for your reply.

First: I need to tell you that the tech did replace my board about three weeks ago and told me it was because of the LED read out not because of a service bulletin.

Second: I have never seen him pull static pressure readings.

Third: Yes I am getting the codes you mentioned 311 and 291 also here is the information from the board Revision U25-1.09, part No. 101573-01, date code 0845J24672.

The dip switch's 8-13 are all in the factory settings. the only switch's I seen him move were dip switch 2 on the board. On the TSTAT I watched and he set for single stage heat pump and dual fuel.

Hope this info will help in resolving my problems
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slctech

2085 Posts

Posted - 03/08/2009 :  6:33:55 PM  Show Profile  Reply with Quote
Your current board is the updated version, however, the ramping options outlined in the bulletin is not set properly. If in fact, the dip switches are all in the factory settings.

I am not saying that this is the cure all for your symptoms, but a good starting point. I would have the technician come back and make the following adjustments as outlined in the bulletin. Also, I would ask about the static pressure measured across the system. With the pressure readings, one can tell if your duct system is adequate enough, or if some modifications should be made.

The only way to properly set-up the dip switches (besides the bulletin's requirements) to meet your needs, is to measure the static pressure. I will take these measurements and using the engineering blower charts and or the first 14 pages of the service manual I attached for you, make the necessary adjustments to perfectly match the system with your duct work.

I am quitting smoking..so I may come across alittle strong...but I am getting sick of our industry and these so-called technicians, that do not utilize the tools given us to properly install and adjust a very high end piece of equipment. These tools consist of manometers, maghelics, inclinometers, thermometers for taking temp drops/rises, and reading the Lennox Bulletins (these are tools, too.).

I hope this helps. There really isn't much more you can do. The furnace is running properly as per how it was designed and currently configured, but with out proper adjustments and the possibility of inadequate duct work, then I think you will find this a persistent issue.

As a Lennox Technician I feel basic repairs and maintenance can be performed by the homeowner. But I highly suggest that periodic maintenance should be made by a certified licensed technician. You should contact your local Lennox technician for any repairs or issues that are outside your comfort zone. Property damage, personal injury, and death can occur from improperly repaired or maintained systems. Replacing a part doesn't always resolve the issue that caused the part to fail!
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webster

3 Posts

Posted - 03/08/2009 :  6:56:13 PM  Show Profile  Reply with Quote
Hi slctech thank you and I will let you know how this turns out possibly I may end up contacting another Lennox service tech.
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nmnunna32

1 Posts

Posted - 08/15/2010 :  10:44:50 PM  Show Profile  Reply with Quote
I am new to this forum...

I am getting E312 displayed on my G71-MPP when my a/c was running abd the blower is at high rpm. Following is the description of the code:

312 Restricted airflow cooling or continuous fan mode #8722; information only

Is there a fix for this? Following is what I was able to get from the board:

Part # 101573-01
S/N 0931J62794
O/S S9240F1004 1

Help please!
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slctech

2085 Posts

Posted - 08/16/2010 :  01:45:13 AM  Show Profile  Reply with Quote
Over time your furnace learns and personalizes itself with how much air it normally requires to properly operate with the combination of ductwork, coil, and filter in your home. When there are excessive restrictions across any one of these, the furnace throws out a non-urgent code. So chances are you had a dirty filter. Change the filter and using the instructions on the panel clear the error codes.


I am not an employee of CozyParts, I generously donate my time. The services here are free, with honest intention to assist, however, this site is not free to maintain. Please make the effort if you need a part or tool to purchase from CozyParts.com. This will ensure this wonderful forum remains for years to come!! As a Lennox Technician I feel basic repairs and maintenance can be performed by the homeowner. But I highly suggest that periodic maintenance should be made by a certified licensed technician. You should contact your local Lennox technician for any repairs or issues that are outside your comfort zone. Property damage, personal injury, and death can occur from improperly repaired or maintained systems. Replacing a part doesn't always resolve the issue that caused the part to fail!
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