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Phil
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 5648
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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Getting "limit switch open" indicator, jumped both and still

Customer Question

Getting "limit switch open" indicator, jumped both and still getting same indicator.
Submitted: 11 months ago.
Category: HVAC
Expert:  BillyHvac replied 11 months ago.

hello,

what position is te furnace in?..upflow or horizontal?

Customer: replied 11 months ago.
Horizontal
Expert:  BillyHvac replied 11 months ago.

Thank you, ***** ***** check the limit in blower section?

see parts on page 14 HERE

Customer: replied 11 months ago.
Put meter on both and both are closed
Expert:  BillyHvac replied 11 months ago.

Thank you, ***** ***** I know you have a meter...

on the board do you see HLO and HLI?

That is for high limit out and high limit in...24v leaves hlo and runs through the limits and returns on hli...if there is 24v on hli then the board is bad...if no 24v on hli then we see if 24v at hlo..

Customer: replied 11 months ago.
I don't have 24 at either, but it fired this time and ran for 5 minutes then tripped. Restarted 3 minutes later ran 5minutes tripped then restarted again.
Expert:  BillyHvac replied 11 months ago.

Is filter clean, blower running registers all open?

BUT....if no 24v at hlo we have a board issue

Customer: replied 11 months ago.
1st thing I did was change filter. Blower running, nothing blocked.
Expert:  BillyHvac replied 11 months ago.

the key will be...when the limit code is flashing...is there 24v on hlo.

Normally limit code is when there is an open in the circuit between hlo and hli