Presents this kind of breakdown the reason to have the following two kinds: 1. The bimetal piece constant temperature temperature is excessively low. This is because the thermostat micro bolt becomes less crowded, with the small screw driver counter clockwise adjustment trimming bolt, after and the repeated test treats the temperature appropriately, the trimming screw retention dies. temperature test available following method: in the counter-clockwise rotation trimming bolt, loads into the gallbladder, and in the gallbladder pours into the water, places in the gallbladder in the glass-stem thermometer, the circular telegram heats up. The attention does not need to press down the push-key switch, observes the thermometer, if the thermometer instructed when the constant temperature temperature is lower than 60 ℃, may again the counter-clockwise rotation trimming bolt; If the thermometer instructed that is higher than 80 ℃, but turns on lathe the trimming bolt clockwise, until the constant temperature temperature in 60 ℃-80 ℃ scopes, namely to move. If does not have the thermometer on hand, may act according to the feeling and the experience. 2. The bimetal piece thermostat electricity contact reed is worn out. Meets this situation to replace the new thermostat.