Forum > Dryer Repair

LG gas dryer wont heat

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JWWebster:
On this dryer the sensor must send signal to the board that ignition has occured and then 90 vdc is sent to the gas valve right? So if his ignitor is firing up that means he has power coming from some relay somewhere other than the control panel. Therefore the  the control thermistat must be some sort of thermister connected to the main board. Are the coils remvable on the gas valve or do you have to replace the whole gas carrying assembly?

RegUS_PatOff:
yes, transformer on control board

(120v AC) ignitor is controller by main board & flame detector & limit thermostats

gas valve is controlled by main board (90v DC)

I'm not sure about the separate coils (I'll check later)

LG Service Manuals




BillR625:
Just so you are aware that when the Radiant Sensor or what I generically call the flame sensor, when that opens it directs 120VAC to the control board, this is how the board knows the ignitor is glowing and is hot enough to ignite the gas,  and using a transformer and a bridge rectifier it drops 120VAC down to 90VDC for the coils to use..   The flame sensor or radiant sensor is nothing other then a safety, the glow bar has to get hot enough to light the gas. The sensor detects the heat and diverts the current to the control board for the gas valve.. Some dyers have a parallel circuit that when the sensor opens it forces current to the gas valves, the amp draw has to be strong enough to operate the coils to open the gas valve.. Depending on the style of ignitor, some operate as low as 2.8 amps while others aew up around 4 amps... They don't want gas pumping into the plenum without sufficient heat to ignite the fumes. So the radiant sensor was added as a safety, nothing else... This tell the gas valve its safe to open in layman's terms...  Imagine 30 or more seconds of gas pumping out of the gas valve as the ignitor is heating up, when it reached a sufficient temp to ignite the fumes, you could have a small explosion on your hands... Strictly a safety...and opening the radiant sensor also kills power to the glow ignitor so it doesn't remain lit...

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