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Tim H.
Tim H., HVAC Professional
Category: HVAC
Satisfied Customers: 3971
Experience:  Experienced in all aspects of HVAC, both residential and commercial.
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Need some help with my furnace. I have a Luxaire gas furnace

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Need some help with my furnace. I have a Luxaire gas furnace that was operating fine yesterday. The unit was turned off overnight, maybe 6-7hrs, while we were sleeping. Now I cannot get it to relight. I have gone through the relight procedure on the inside panel at least three times. The blower itself is on and purring. The sight window has a red light blinking 4 times and then pausing before it blinks again.

Tim H :

Thanks for giving me the opportunity to help! If you check inside the lower furnace door, there is usually a "legend" that identifies the different codes. Can you help me find out what 4 flashes means?

JACUSTOMER-r9175aj7- :

Just looked it up

JACUSTOMER-r9175aj7- :

Open high limit switch

Tim H :

Did you perhaps leave a filter in too long and it got clogged?

JACUSTOMER-r9175aj7- :

Just checked the filter. It does need to be changed. Will that prevent the furnace from igniting again?

Tim H :

Well, what can happen is if filter is left in too long and furnace can't move enough air and gets too hot, this can take out the high limit switch. Other causes are bad blower, etc.

JACUSTOMER-r9175aj7- :

I popped out the filter for the time being. I am turning the furnace back on and waiting. Please hold.

Tim H :

See this posting.......click here

JACUSTOMER-r9175aj7- :

Let me take a look for that reset switch

Tim H :

OK, otherwise you can try turning the furnace power off and back on. This will reset it.

JACUSTOMER-r9175aj7- :

Not seeing anything like a reset switch or what that link indicated. Restarting now. One moment please

Tim H :

OK

JACUSTOMER-r9175aj7- :

Replaced the panel and turned the power back on. Been about 2 minutes. Still do not have ignition

Tim H :

Are you getting 4 flashes?

JACUSTOMER-r9175aj7- :

yes, I still am

JACUSTOMER-r9175aj7- :

I am still seeing the 4 flashes

Tim H :

OK, then the main high limit switch is probably going to have to be replaced. Do you have an ohmmeter?

JACUSTOMER-r9175aj7- :

Unfortunately no. Although I can go get one. Besides the high limit switch, is there any other possible causes that I can try first before I leave the house to get a meter?

JACUSTOMER-r9175aj7- :

And where would that switch be if it were bad?

Tim H :

Yes, try this: First turn the furnace power off.Take the two wires off the limit switch which sits right above the burners and tape the metal ends together. Make sure they aren't touching anything else such as a ground. Now turn furnace power back on and see what happens.

JACUSTOMER-r9175aj7- :

Okay. Be right back

Tim H :

I'll stand by...

JACUSTOMER-r9175aj7- :

Did as you instructed. It is on, but still no reignition

Tim H :

Did you turn thermostat up enough for it to kick on? Is it still showing 4 flashes?

JACUSTOMER-r9175aj7- :

yes to both. The gas did not relight but the blower and the usual clicks you hear when the thermostat is triggered occurred.

JACUSTOMER-r9175aj7- :

I could send you a picture of what I did.

Tim H :

OK, then if you did properly tape the leads together, we have eliminated the main high limit as the culprit. Look around the burner area for one of these switches and if you find--push in the button

JACUSTOMER-r9175aj7- :

Sorry about the wait. No such luck. I detached and reattached those wires just to make sure. Looked all over for any button to reset,but still nothing.

Tim H :

OK. I don't know how much more I can help. You have an open high limit somewhere. Limit switches are typically located in and around the burner area and in some cases, by the blower motor. You have to find and replace the open switch by locating it first. I previously sent you a post that shows what different types of high limit switches look like.

Tim H :

Cut the furnace power off completely to reset. This is best done by a switch on the side or a circuit breaker.

Tim H :

I'll switch to Q and A mode and you can still post questions.

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