Evaporator Temperature Sensor / Switch: Testing and Inspection

1. Turn ignition On, turn blower On, and measure voltage at terminals L/W and R/B of the thermo switch connector.
2. L/W should read 0V, if not, repair wiring as necessary.
3. R/B should read 12V, if not check ECU operation. If 12V is read and evaporator surface temperature is below 32°F, system is operating normal. If not, replace thermo switch.