Clean the coils with water or noncorrosive coil cleaner Clean the drain line, “P” trap, and condensate pan. Check refrigerant pressures and temperatures every Spring. Check heating section every Fall. Check all electrical connections for tightness and check heater elements for indications of overheating. M2 Series units use backward curved fan wheels which are non-overloading, energy efficient and easy to clean. Cleaning the wheels is necessary to reduce electrical use, maintain capacity, and reduce stress on the unit. The wheel and fan section need to be inspected periodically and cleaned of dust or debris. To inspect and clean the blower, set thermostat to the “OFF” position. Turn the electrical power to the unit to the “OFF” position at the disconnect switch. Clean the assembly. Check the bearings. Inspect the belt condition and tightness. Check screws for tightness. Rotate blower wheels while listening closely to each bearing to check for noise or roughness in the bearing, which can indicate a failing bearing. AAON uses pre-lubricated bearings, and bearings that have been sized for an average failure rate of 50% after 200,000 hours, or 22.8 years, of operation (see heading “Lubrication” in this section for more information). The bearing sizing tables below are based on rotational speeds and radial loading. However, the alignment of the bearing to the shaft and the security of the bearing inner race to the shaft will greatly affect bearing life. Even though the manufacturer is responsible for bearing tolerances and mounting design, the servicer is advised to regularly check the security of the bearing locking system. Belt drive misalignment is one of the most common causes of premature belt failure. A belt can be destroyed in a matter of days if the drives have been aligned incorrectly. The most common tool for measuring misalignment is a straightedge. Hold the straightedge flush across one pulley to gauge the degree of misalignment of the two sheaves. The maximum allowed misalignment is one half degree of angular misalignment, and 1/10th of an inch per foot between sheave centers for parallel misalignment. Correct by moving the position of the motor. Correct by adjusting sheaves on one, or both shafts. Frequent belt tensioning is highly recommended. Most belt manufacturers would suggest a re-tensioning after as little as 8 hours of operation. A simplified method of adjusting tension is to gauge the amount of force required to deflect the belt by 1/64th of an inch per inch of distance between sheave centers. For example, if the sheaves are 20 inches apart, then the amount of deflection with the forces listed below is 20/64th (5/16th) of an inch. Indoor cooling/evaporator coils must be cleaned regularly to maintain unit efficiency and operation. Dirty evaporator coils will eventually freeze up and often result in a time consuming and expensive service call. Clean filters will help to prevent dirt from accumulating on cooling coils, however cooling coils should be cleaned at least annually by an HVAC professional. Satisfactory performance of the refrigeration cycle can be determined by measuring suction line superheat. In order to determine if refrigerant flowing from the evaporator is dry, ensure that the system has enough refrigerant to produce liquid line subcoo Refrigerant cycle analysis is best performed in conditions that approach the conditions where the air conditioner will be expected to operate. Because of a normally high degree of turbulence in brazed plate heat exchangers, for many applications the heat exchanger channels are self-cleaning. For applications that are not self-cleaning (i.e. hard water at high temperatures, etc.) or applications where additional cleaning is desired, it is possible to clean the brazed plate heat exchanger by circulating a cleaning liquid. Use a tank with weak acid, 5% phosphoric acid (H3PO4) or, if the exchanger is frequently cleaned, 5% oxalic acid (H2C2O4). Pump the cleaning liquid through the exchanger. For optimum cleaning, the cleaning solution flow rate should be a minimum of 1.5 times the normal flow rate, preferably in a back-flush mode. After cleaning, the heat exchanger must be rinsed with clean water. A solution of 1-2% sodium hydroxide (NaOH) or Documented routine cleaning of e-coated coils is required to maintain coating warranty coverage. Surface loaded fibers or dirt should be removed prior to water rinse to prevent restriction of airflow. If unable to back wash the side of the coil opposite of the coils entering air side, then surface loaded fibers or dirt should be removed with a vacuum If a vacuum cleaner is not available, a soft non-metallic bristle brush may be used. In either case, the tool should be applied in the direction of the fins. Coil surfaces can be easily damaged (fin edges bent over) if the tool is applied across the fins Use of a water stream, such as a garden hose, against a surface loaded coil will drive the fibers and dirt into the coil. This will make cleaning efforts more difficult. Surface loaded fibers must be completely removed prior to using low velocity clean wa A monthly clean water rinse is recommended for coils that are applied in coastal or industrial environments to help to remove chlorides, dirt, and debris. It is very important when rinsing, that water temperature is less than 130°F and pressure is than 10 Coil cleaning shall be part of the unit’s regularly scheduled maintenance procedures. Failure to clean an e-coated coil will void the warranty and may result in reduced efficiency and durability. CAUTION! Harsh chemicals, household bleach, or acid cleaners should not be used to clean outdoor or indoor e-coated coils. These cleaners can be very difficult to rinse out of the coil and can accelerate corrosion and attack the e-coating. If there is dir For routine quarterly cleaning, first clean the coil with the below approved coil cleaner. After cleaning the coils with the approved cleaning agent, use the approved chloride remover to remove soluble salts and revitalize the unit. Enviro-Coil Concentrate, Part Number HEC01. CHLOR*RID DTS™ should be used to remove soluble salts from the e-coated coil, but the directions must be followed closely. This product is not intended for use as a degreaser. Any grease or oil film should first be removed with the approved cleaning agent Soluble salts adhere themselves to the substrate. For the effective use of this product, the product must be able to come in contact with the salts. These salts may be beneath any soils, grease or dirt; therefore, these barriers must be removed prior to application of this product. As in all surface preparation, the best work yields the best results. Apply directly onto the substrate. Sufficient product must be applied uniformly across the substrate to thoroughly wet out surface, with no areas missed. This may be accomplished by use of a pump-up sprayer or conventional spray gun. The method does not matter, as long as the entire area to be cleaned is wetted. After the substrate has been thoroughly wetted, the salts will be soluble and is now only necessary to rinse them off. It is highly recommended that a hose be used, as a pressure washer will damage the fins. The water to be used for the rinse is recommended to be of potable quality, though a lesser quality of water may be used if a small amount of CHLOR*RID DTS is added. Check with CHLOR*RID International, Inc. for recommendations on lesser quality rinse water. Set thermostat in the heat mode; call for heat to engage all electric heat strips. Check blower for proper rotation and voltage. Measure the amperage and voltage. Compare them to the nameplate data. If applicable, check remote heat pump condenser as per the manufacturer’s recommendations. Set thermostat in the heat mode. Observe supply blower for proper rotation and voltage. Check boiler or hot water operation according to the manufacturer’s instructions. Check control flow valves for correct operation and settings per the manufacturer’s instructions. Inspect and clean unit interior at the beginning of each heating and cooling season and as operating conditions require. Check remote chiller operations as per the manufacturer’s instructions. Check coolant flow valves for correct operation and settings. Set unit controls to cooling mode of operation with supply fans on. Check the fan for correct operating direction, amperage, and voltage. Check compressor operation, rotation, amperage, and voltage to the unit nameplate (check the amperage on the load side of the compressor contactor). Drain pans will have moisture present and require periodic cleaning to prevent microbial growth. Cleaning of the drain pans will also prevent any possible plugging of the drain lines and overflow of the pan itself. Cleaning of the drain pans and inside of the unit should be done only by a qualified service technician. condition of the burners heat exchanger draft inducer vent system operating controls wiring Check for obvious signs of deterioration, accumulation of dirt and debris and any heat or water related damage. Any damaged or deteriorated parts should be replaced before the unit is put back into service. Check the automatic gas valve to insure the gas valve seat is not leaking. Check wiring connections to be sure they are secure and inspect wiring for any deterioration. Most motors and bearings are permanently lubricated. Some applications may require that bearings be re-lubricated periodically. The schedule will depend on the operating duty, temperature variations, and other atmospheric conditions. For bearings equipped with lubrication fittings, the lubrication schedule is dependent on operating temperatures and rotational speeds as shown in the table below. Lithium based grease conforming to an NLGI grade No. 2 consistency is recommended. This medium viscosity, low torque grease is rust inhibiting and waterresistant. It is satisfactory for operating temperatures in the range of –10F to 250F. Bearings should only be re-lubricated when at normal operating temperatures and not running. Rotate the fan shaft by hand, adding only enough grease to purge the seals. A one-inch bearing has a total grease capacity of only .25 ounces. Added grease should In the event the unit is not functioning correctly and a service company is required, only a company with service technicians qualified and experienced in both commercial heating and air conditioning should be permitted to service the systems in order to Parts for AAON equipment may be obtained from your local AAON representative. When ordering parts, reference the unit serial number and part number.