Carrier P User Manual

52C,PSERIES18HEATERSThe heater in 52C,P units is located directly behindthe evaporator coil. The heater assembly includes theheater (2.3 kW, 3.4 kW or 5 kW), a primary limitswitch, and a secondary limit switch. See Figure 34.The primary and secondary limit switches are safetyswitches that regulate heater operation. The primarylimit switch disables current to the heater when thetemperature exceeds the setting on the switch.For example, a 3.4 kW heater may have a primarylimit switch setting of 150 F. If the temperature at theswitch exceeds 150 F, the primary limit switch willelectrically open and shut off power to the heater.Once the temperature drops below 110 F, the primarylimit switch will automatically reset.The secondary limit switch works in the same manneras the primary limit switch, except it is a one timeswitch and has a slightly higher temperature setting.Once this switch is thermally opened, it must bereplaced. Together the primary and secondaryswitches help maintain safe temperature limits forunit operation.COMMON CAUSES OFHEATER FAILUREHeater failure may result from broken heater coils,primary limit switch failure, or an open secondarylimit switch. These conditions are generally caused bylow or no airflow.HEATER REMOVALBefore working on the heater, read the instructionsthoroughly and gather the necessary tools for the job.Review all safety information on the unit and in theproduct literature.The manufacturer reserves the right to discontinue, orchange at any time, specifications or designs withoutnotice and without incurring obligations.Before performing any cleaning, servicing, or main-tenance to the unit, Disconnect All Power to avoidthe possibility of electric shock and personal injury.Consider the following safety issues:• Prior to performing any service or maintenance onelectrical equipment you must Disconnect AllPower.• New and unfamiliar tasks should be performedunder the supervision of an experienced servicetechnician.• Personal protective equipment, such as safetyglasses and work gloves, should be worn.• The floor around the work area should be clean andfree of debris.• Make sure tools are the correct tools for the job,and that they are working properly and in goodcondition.FIGURE 34 — LIMIT SWITCH LOCATION