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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22518
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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Trane furnace flashing 2 red light system lockout. How to unlock?

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My Trane furnace is flashing the 2 red light system lockout code. It does this every year! Unfortunately, this year, I am on my own and don't know what to do... How do I unlock my lockout?



Can you tell me what happens when the furnace starts?

Exhaust motor runs....glow appears at front of burners....gas valve opens and flame occurs...etc...

This code means no flame ...but it can be bad igniter or dirty sensor...telling me what happens will help.

Customer: replied 6 years ago.

The unit is turning on. I don't see any glow, and it's just throwing out cold air. I have to unplug the unit itself to get the cold air to stop. It doesn't look like there's a flame...

Ok, it sounds like a broken igniter. Do you know what this is?

Customer: replied 6 years ago.

No. I assume it means nothing is starting the flame? But here's the deal - I have already had the igniter fixed, and it continued to happen throughout the season last year - my boyfriend at the time could always get it running.... but unfortunately, I kinda stopped seeing him so I don't feel right asking him to fix it :(

I've had the house 3 years - I've had the whole control panel replaced and gas line fixed and igniter fixed. Do you think it's still the igniter or could it be something else?

This will help. Get pen and paper

Start furnace

Write down all times, sounds, clicks etc...

Fan starts


Sound....etc..then tell me what we have start to finish.

Customer: replied 6 years ago.

Gotcha. I'm on it!

Okay, the light starts out flashing normally.

I hear the unit start up, it clicks, 30 seconds or so and I hear the flame ignite.

Light normal, clicks, fan on, now it's normal and working.

You fixed it.

All I did was assure all the fuses were in and wiggled them.

Also, I think I maybe did the gas shut-off/wait 5 minutes/turn back on thing. But I'm not sure, because I don't have a diagram of the control panel (I just looked for on/off switches and there was only one - a series of three - that I could find).

Do you have a possible diagnosis? And is that the gas shut-off valve? Again, I had the control panel replaced last year.

PS - Thank you a TON.

Ok....magic...that time of year...Smile

I am hoping the flame sensor is just dirty. At one end of the burner is a glow the other end is a flame sensor which is a metal rod that sticks in front of the has a white ceramic base.

You can clean the flame sensor with steel wool. I really hope things turn to the best for you. Any time you need help, just return here.

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