I have bought the mk139 kit but it does not work when i clap the relay light works but the relay is always connected from COM to NC but when the relay light is on 12v go through relay but it doesn’t switch between NC and NO is this a relay problem?
Remove the relay from the pcb and apply 12VDC to its coil. Check the contacts with a multimeter. If the relay proves defective (very unlikely but possible) replace it with an identical type.