What Are the Causes of a Thermo King Air Flow Alarm?

The Thermo King cooling and heating unit is useful for the regulation of temperature inside the cabins of trucks, trailers and large passenger vehicles. It has many capabilities, including the ability to balance the flow of air, keep goods frozen for long-distance travel and even defrost them before unloading. Whenever an abnormality occurs with one of the Thermo King's parts, an alarm will sound. Some alarms require immediate attention, while others act as friendly maintenance reminders.

Functional Alarms

• Some Thermo King Air Flow alarm codes refer to the device's functional settings, and do not require further action be taken by the user. They only alert users to normal system processes. For instance, codes 117 and 118 refer to an automatic switch from diesel-to-electric or electric-to-diesel energy consumption. Code 01 appears when the system is either first being set up or is being reset.

Temperature Load Monitoring

• When certain engine parts or unit sensors begin to overheat or malfunction, the alarm will sound. The following parts require constant monitoring and end-of-the-day alarm reporting, should their codes appear on the system (they are listed with their codes in parentheses): the evaporator coil sensor (02); evaporator coil inlet temperature sensor (123); discharge air sensors (04, 204); return air sensors (03, 203); air flow (46); heating and cooling cycles (21, 22); defrost damper circuit (29); modulation circuit (34); water valve circuit (39); electric heat circuit (113;, engine coolant temperature (83); heater fuel level (103); remote fan speed (104); and back pressure regulator (126).

Immediate Repair

• Some alarms shut down the Thermo King Air Flow. These alarms are heard when dangerous situations arise requiring immediate repair. They include: low and high evaporator temperature (09, 101, 102); high discharge pressure or temperature (10, 82, 93, 99); motor failure (27, 36); oil pressure failure (19, 27, 66); high engine coolant temperature (18); sensor shutdown (12, 47, 97, 125); engine failure (17, 20, 63); battery failure (61); alternator failure (25); cooling or heating cycle failure (23, 24, 65); intake air heater failure (15); stuck defrost damper (30); low refrigeration capacity (32); circuit failure (35, 40, 45, 51-53, 60, 62, 67, 69, 89-91, 94-95, 105-107, 110, 120-122); electric phase reversal (38); fuel system failure (44, 96); failed belts or clutch (48); controller/computer failure (75-78); remote fan failure (112); and high-pressure cut-out switch failure (115).

Non-Urgent Alarms

• Some alarms refer to situations that should be reported at the end of a day. They do not require immediate attention in the form of monitoring or repair. They include: possible unit start-up or self-check malfunctions (16, 28, 84, 85, 111); unit settings malfunctions (50, 54, 64, 68, 70-74, 79, 134-136); unit speed malfunction (42, 43); sensor malfunctions (05-07, 86-87, 98, 124); defrost termination malfunction (14); poor engine idling level (33); inadequate engine coolant (37, 41); engine speed deficiency (55); evaporator and condenser fan speed malfunctions (56-59); compressor temperature malfunctions (80, 81); high-pressure cut-in switch malfunction (116); and maintenance reminders (128-133).