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avatar: menotyou9
menotyou9
2 posts
Replied to menotyou9's post on May 21st, 2020

I keep getting the error message "power supply furnace impredance error(405)" and "power supply furnace impredance error, value 127, max=0, min = 0, (420)". I've restarted, and cleand the furnace and jacket with no luck.

Any help?

avatar: menotyou9
menotyou9
2 posts
Replied to menotyou9's post on May 29th, 2020

SOLVED

For future google searches, here are some reccomendations I got.

Check the thermocouple. The T/C has two sensors for two functions- sample temperature and runaway temperature safety control.  If the sample temperature readout on control panel appears normal, the other sensor could be burned out leading to the furnace impedance error. 

Check the power supply fan in the back. If this is bad then the power supply is overheating and can give a furnace error.

IF both of those are still good, then take the furnace off the TGA . Then test furance lead with a multimeter set to the Ohms read-out.
For my Q500 normal furnace the top two leads were  measured. A good furnace will have ~4 Ohms. Mine read 214 ohms which indicated the wiring had gone bad and needed to be replaced.

Hope this helps future people.