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JulesB 01-26-2011 12:01 PM

Guardian furnace 11 red code issue
My sister called me this morning stating her furnace is down. It's about a three year old Guardian 90% (out of warranty) that's giving a flashing red 11 times.
It starts the cycle, then shuts itself down. That's all I know at the moment. When she gets home from work, I can get more details from her. Just thought I'd try to help her out before she calls a repair man. The whole husband laid off, no money thing going on. And it's an hour + drive for me to go and flail around attempting to fix it.

I googled, and believe the code is a - open limit switch/blower failure code

any and all help greatly appreciated.

JulesB 01-26-2011 01:50 PM

additional info
had my sister check a few items.

Cycle starts up. exhaust fan runs, then main fan comes on, but the igniter doesn't light up. Main fan runs for a brief while blowing cold air, then the system shuts down.

Sometimes a 11 red code. sometimes a 4 red code. and sometimes it would give the slow green flashing as if nothing is wrong. Most of the time, it gave the green while attempting to run.

I had her check for obvious things like upstructions to the air intake, the exhaust outside, even had her check to see if there was anything in the squirrel cage since both those red codes refer to the fan. I also had her pull the igniter out to give it a visual. Seemed good to her.

My next thought is the gas line having an obstruction in it???

any help would be great....

hvactech126 01-26-2011 01:58 PM

there should be an index of the trouble codes on the inside of the blower door or possibly the burner door. CK FILTER?!

JulesB 01-26-2011 02:39 PM


Originally Posted by hvactech126 (Post 578430)
there should be an index of the trouble codes on the inside of the blower door or possibly the burner door. CK FILTER?!

for whatever reason, this unit doesn't list the codes on the inside of the door, like most. I had her dig out the users manual. code 11 refers specifically and only about the main fan. Which seems to be functioning fine. It spins freely, doesn't make any noise, or smell.
Code 4 refers to the fan, as well as filter, and a couple items such as improper duct size, etc. Issues that I assume would of been a problem immediately, not 3 years after the install.
Both are open limit switches.

Filter is clear.

hvactech126 01-26-2011 02:42 PM

sounds like an open limit then

JulesB 01-26-2011 02:49 PM


Originally Posted by hvactech126 (Post 578458)
sounds like an open limit then

this is where I start talking over my head, so bare with me....

A limit switch is nothing more than a safety on/off switch correct? And if so, then something is causing the switch to be interrupted? If that's the case, then the furnace either has a faulty part, or faulty operating conditions?? (which I feel like I've explored most/all of those) Or, I suppose a faulty limit switch?

hvactech126 01-26-2011 03:04 PM

a limit switch is normally closed, and opens when a fault is detected. Some are manually reset and some are auto reset. Auto reset switches do get stuck when they are tripped too many times.

JulesB 01-26-2011 03:20 PM

thanks for your input tech126. much appreciated.

JulesB 01-26-2011 07:52 PM

Repairman diagnosed it as a bad limit switch. He didn't have the proper one on his truck, so he "hot wired" the unit to work for the evening. (I'm no rocket scientist, but I'd guess that this was "illegal". Not that my sis is complaining. Heat is heat) Also said that the condensation drain was leaking into the bottom of the unit, which collaberates with an issue she was having last summer. Curious to know if the leaking created the failed limit switch??
Will have more details tomorrow AM........

hvactech126 01-26-2011 08:02 PM

YOU DONT JUMPEROUT ANY LIMIT! IT IS A SAFETY DEVICE. He is making himself liable if the unit overheats causes property damage or death. she should call the company and ask them about their policy of bypassing safety devices on furnaces and also call the BBB.

Marty S. 01-26-2011 08:37 PM

AMEN! That limit failed because the furnace overheated so many times. Now it's going to overheat with no safety to shut the furnace off. Call up your sister and tell her to shut the furnace off and put up with being cold one more night.

beenthere 01-27-2011 03:54 AM

As above. That limit switch would not have failed open, if there was no reason for it to be open.

Now your sis has a furnace running that is over heating, and could cause injury to her and her family.

JulesB 01-27-2011 08:07 AM

Comments much appreciated. It didn't sit well with me either. Amazing, as this is a larger, reputable local company, with no infractions listed with the BBB. My sister is quit anal when hiring strangers, and did the research previous to hiring them.

I did get more of the story. Seems her husband (bless his heart) hadn't been changing the filter. When I spoke to her yesterday, I guess he'd just changed it. I had her go find the old one. Let's just say, they have a lot of cats.....

Anyway, the dirty filter collaborates with what the technician came up with.......a bad limit switch due to restricted air flow.

Thanks again for the comments and concerns.

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