goodman GDS80703AXBC high limit switch


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Old 12-02-11, 08:55 PM
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goodman GDS80703AXBC high limit switch

I have been searching posts for a few days now and haven't found the exact problem I am experiencing.

My furnace is about 4 years old and a few days ago my wife woke me up in the middle of the night b/c she said it's freezing in the house. Sure enough, cold air was blowing out of the vent in our bedroom. I went to check the furnace and the indicator was blinking 4 times. I shut off the thermostat and then the furnace itself. I left it off for 5 minutes and turned it back on with no problems.

After about 4 times of turning on and off...it started to act up again. The furnace would run, then as it was cycling down try to kick back on again (ignite)...it would sound as if it was going to then just stop. The fan would continue to run, the Thermostat still said "heat on" and cold air was coming out.

This has gone on for 2 days now...furnace would work fine for 5-10 hours then the above. I have done the following:

1. replaced the filters - I had the pleated in there for about 4 weeks (says it can stay for up to 3 months so I thought that was fine)
2. cleaned off the flame/heat sensor
3. reset the cables on the limit switch

Do I need a new limit switch? The parts not expensive so I figured I should go pick on up tomorrow morning.

Thanks!
 
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Old 12-03-11, 04:14 AM
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you may need a limit if its not resetting on its own, however you need to first determine the cause of the overheating condition. remove the filters form the system and see if it still happens. Your filters may be too restrictive for your setup. Make sure ALL registers are open. Make sure the Evap coil is clean.

TIP -
1. replaced the filters - I had the pleated in there for about 4 weeks (says it can stay for up to 3 months so I thought that was fine)
The magic words of your statement and how the manufacturer got you to buy THOSE filters was "up to 3 months", which does not mean that they will last for 3 months in every situation/home. Pleated filters, no matter the manufacturer should really be replaced every month.
 
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Old 12-03-11, 05:03 AM
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Thank you hvactechfw

Originally Posted by hvactechfw
Make sure the Evap coil is clean.
There is no AC unit connected...do I still have an evap coil?

Well now the furnace doesn't light at all! When I turn it on it doesn't ignite, and immediately starts flashing 4 times. I left it off for 5 hours and that didn't do the trick.

The filters that are in there now are the cheap 1.40 filters...do you think I should remove those?

Worried the kids can't take another night of no heat...should I go get another limit switch?
 
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Old 12-03-11, 05:09 AM
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yes, get a new limit switch, no ac = no evap coil. for time being remove the limit switch and hold a lighter near the sensing side and it may pop and start working. However, this limit should only be used temporarily until you replace with a new limit. Something is causing the furnace to overheat or something is leaking onto the limit and causing it to trip. The limit should be auto resetting, it is not resetting because it is worn out from the limit tripping too many times.
 
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Old 12-03-11, 05:18 AM
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Originally Posted by hvactechfw
yes, get a new limit switch, no ac = no evap coil. for time being remove the limit switch and hold a lighter near the sensing side and it may pop and start working. However, this limit should only be used temporarily until you replace with a new limit. Something is causing the furnace to overheat or something is leaking onto the limit and causing it to trip. The limit should be auto resetting, it is not resetting because it is worn out from the limit tripping too many times.
Should the unit be off when I do this?

I'll be going to get another one as soon as the plumbing supply store opens this morning.
 
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Old 12-03-11, 05:21 AM
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yes, it should be off. remove the limit and then proceed.
 
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Old 12-03-11, 05:30 AM
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I removed the limit, the L300-30F limit switch, held the lighter to the side with the sensor for about 30 seconds. hooked it back up, power to the furnace, then put the thermostat to heat - got a solid red indicator for about 10 seconds and then it seemed like it 'clicked' (sorry for the description) and then started flashing 4 times and the blower started blowing out cold air.

Did I do that correctly? May just need to wait to replace the L300-30F limit?
 
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Old 12-03-11, 05:45 AM
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yep. just replace the limit.
 
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Old 12-03-11, 05:52 AM
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Just to keep you in the loop. I noticed another 'limit'...this one was smaller and said L300F on it. This one is mounted directly above the burners (this is a down flow furnace) and is much smaller with a little red rod on the one side and the sensor on the other. Is this the limit in question? I did what you suggested with this little guy...turned the furnace back on and it's been working for about 5 minutes.

So I've identified 2 limits

L300-30F : larger and the sensor side can't be seen - sensor side is on the interior of the furnace

L300F : smaller and the sensor side can be seen - sensor side is right above the burners/flame.

Are these both a fault here? Sorry for all the questions and I appreciate the help here.
 
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Old 12-03-11, 05:57 AM
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the red button is to reset that little limit which is a roll-out limit....if the flames are rolling out and tripping that limit you need to call a pro!
 
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Old 12-03-11, 06:04 AM
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Well this morning before I started this up again there were no flames at all, the 'bulb' wouldn't even light or anything. This is the first time that it ignited at all...it's been on now for about 8 minutes.

If I press little red tab, it doesn't click or seem like it does anything really.

So this is what I did last before it started working.
Removed the larger limit - held the lighter to the sensor side for 30 seconds
Turned back on - nothing
Turned off
Traced the wires from the larger limit to the board (grouped with a bunch of others in a large clip) - removed from the board and then reconnected
Removed the smaller limit - held the lighter to that sensor side for 30 seconds
Turned back on - so far so good

Do you really think the small limit is the issue still? I have no issue calling someone in but would much rather get these resolved myself if I could. The last time someone came out (with my old furnace) it cost me almost 400 for them to add a screw some where.

Thanks again.
 
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Old 12-03-11, 06:10 AM
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let the system run and see what happens. the little red button does nothing unless the limit is tripped. If the limit were tripped and you pressed the button you would feel/hear a click. What you previously described does not at all sound like the rollout switch was tripped. I think it was when you removed power from the main limit by disconnecting them from the board that it reset.
 
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Old 12-03-11, 06:17 AM
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Originally Posted by hvactechfw
let the system run and see what happens. the little red button does nothing unless the limit is tripped. If the limit were tripped and you pressed the button you would feel/hear a click. What you previously described does not at all sound like the rollout switch was tripped. I think it was when you removed power from the main limit by disconnecting them from the board that it reset.
thanks again hvactechfw - it's still running now...this is the longest since yesterday around dinner time.

the pluming supply store is open now...I wonder if I should go down there and buy another just so I have one?
 
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Old 12-03-11, 06:20 AM
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I would, they are cheap if they have one available for your unit.
 
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Old 12-03-11, 07:56 AM
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Happened again...it's weird b/c it starts acting up when:

Furnace is cycling down (if that makes sense) and it starts the heating sequence again (b/c the Thermostat went below the set temp). That's when it will try to ignite again but won't.

Going to see if they have a high limit for my unit and then replace.
 
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Old 12-03-11, 08:18 AM
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Well, the pluming supply store won't sell it to me b/c I am not a licensed contractor...may need to order it online now.
 
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Old 12-05-11, 07:54 AM
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My brother in-law was able to get me one from a place that would sell it. Installed the new limit...furnace worked for 30 minutes and now it's doing the same thing...4 blinks and not igniting.

So,

Replaced filters
Installed new limit

Same error code...really puzzled now.
 
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Old 12-25-11, 09:34 AM
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goodman problem

if you have some way tomeasure temperature at the limit switch,such as a fluke with a thermocouple you could get an idea of what the actuasltemeprature is....goodmans are known for cracked/defective heat exchangers. if it keep tripping the limit,the heat exchanger may have ahole or crack in it. I would have it checked by a pro and get some carbon monoxide detectors.
 
 

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