Limit Switch Open Error ICP Furance

[The Gaffer]

Have a customer with a ICP high efficiency furnace, throwing a 4 flashing light code, limit switch open. Here is what I have done so far (most as part of general service):
Changed 2 x limit switch
Changed Pressure switch
Changed ignitor
Changed flame sensor
Changed board

Anyone any ideas with these furnaces as to why it would still throw this code after this?

[Snapperhead]

Have you made sure polarity is correct , you know , the switch on blower door is hot ( not neutral) and the ground is nice and snug

[Pnasty]

Is the limit actually open?
Did you replace all those things in response to this one error code?
Are you a technician? If you are you need to contact a more senior tech to show you how to trouble shoot properly. You have replaced everything but motors and heat exchanger, customer would have been better off with a sales tech in this case.

[The Gaffer]

The main fan comes
On when the switch is activated but that is as far as the cycle goes

[Snapperhead]

Do you know how to test across a safety switch to see if its open or closed ?

You know its got a couple different high limits ... right

Some have 3 - 4 of them

[pecmsg]

Call A professional

[jbhenergy]

Limit switch or pressure switch?

If limit switch why replace a pressure switch?
Or vise versa?

Like others said, is the limit actually open? Ohm meter the limits and see if they are open and close.

After the furnace is off for an hour does the furnace run at all or go right to error code?

Which limit, roll out or HX high limit?


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[rundawg]

Have a customer with a ICP high efficiency furnace, throwing a 4 flashing light code, limit switch open.

Model number please.

[jmac00]

some furnaces have a limit switch on the blower housing, which MANY techs miss.

someone needs to figure out how to test a safety circuit, instead of loading up the parts cannon

[Adlerberts-Protege]

some furnaces have a limit switch on the blower housing, which MANY techs miss.

someone needs to figure out how to test a safety circuit, instead of loading up the parts cannon

Bingo!! These get missed all the time. Betcha that's what it is.

[jbhenergy]

some furnaces have a limit switch on the blower housing, which MANY techs miss.

someone needs to figure out how to test a safety circuit, instead of loading up the parts cannon

Do icp have those? I know that’s a big trane thing.


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[GenesisRefrig]

He forgot to change the inducer motor and heat exchanger. I hate when people only replace MOST of the parts. Do the job right, and replace them all. Darn Millennials!

[kdean1]

Have a customer with a ICP high efficiency furnace, throwing a 4 flashing light code, limit switch open. Here is what I have done so far (most as part of general service):
Changed 2 x limit switch
Changed Pressure switch
Changed ignitor
Changed flame sensor
Changed board

Anyone any ideas with these furnaces as to why it would still throw this code after this?

Wow! That’s getting expensive. Evidently none of those parts were bad. Tell us what you measured instead of what you guessed at.

[jmac00]

Do icp have those? I know that’s a big trane thing.


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not sure about ICP, ya Trane and Rheem both have them on the blower housing, but it this ICP is a multi-position unit, it should have a limit on the blower housing

[Rovert]

Have you actually confirmed that the temp isn't getting too high? Checked the filter/airflow/TESP?

[customheating]

Can tell your not experienced, cause for a limit code, there are 100 things I would have done before changing the ignitor or flame sensor. When it gives a code, it usually does not mean new part. Think of why the main limit would be kicking out. Heres a hint: something is probably needing cleaned