Horizon™ Dedicated Outdoor Air Systems: Monthly Maintenance

Cooling Season

• Check the unit’s drain pans and condensate piping to ensure that there are no blockages.

• Inspect the evaporator and condenser coils for dirt, bent fins, etc. If the coils appear dirty, clean them according to the instructions described in “Coil Cleaning” later in this section.

• Manually rotate the condenser fans to ensure free movement and check motor bearings for wear. Verify that all of the fan mounting hardware is tight.

• Inspect the F/A-R/A damper hinges and pins to ensure that all moving parts are securely mounted. Keep the blades clean as necessary.

• Verify that all damper linkages move freely; lubricate with white grease, if necessary.

• Check supply fan motor bearings; repair or replace the motor as necessary.

• Check the fan shaft bearings for wear. Replace the bearings as necessary.

• Check the supply fan belt(s). If the belts are frayed or worn, replace them. Refer to the “Fan Belt Adjustment-Belt Drive Units,” p. 36 for belt replacement and adjustments.

• Verify that all wire terminal connections are tight.

• Remove any corrosion present on the exterior surfaces of the unit and repaint these areas.

• Generally inspect the unit for unusual conditions (e. g., loose access panels, leaking piping connections, etc.)

• Make sure that all retaining screws are reinstalled in the unit access panels once these checks are complete.

With the unit running, check and record the following:

• ambient temperature

• compressor oil level (each circuit)

• compressor suction and discharge pressures (each circuit)

• superheat and subcooling (each circuit)

Heating Season

• Inspect the unit’s air filters. If necessary, clean or replace them.

• Check supply fan motor bearings; repair or replace the motor as necessary.

• Inspect both the main unit control panel and heat section control box for loose electrical components and terminal connections, as well as damaged wire insulation. Make any necessary repairs.

• Verify that the electric heat system operates properly.

Regular coil maintenance, including annual cleaning enhances the unit’s operating efficiency by minimizing the following:

• Compressor head pressure and amperage draw

• Evaporator water carryover

• Fan brake horsepower

• Static pressure losses

• Airflow reduction

For evaporator coil cleaners, contact the local Trane Parts Center for appropriate detergents.

• Remove enough panels from the unit to gain safe access to coils.

• Straighten any bent coil fins with a fin comb.

• For accessible areas, remove loose dirt and debris from both sides of the coil.

• When cleaning evaporator coils, mix the detergent with water according to the manufacturer’s instructions. If desired, heat the solution to 150° F maximum to improve its cleansing capability.

• Important: DO NOT use any detergents with microchannel coils. Pressurized water or air ONLY.

• Pour the cleaning solution into the sprayer. If a high-pressure sprayer is used: a. The minimum nozzle spray angle is 15 degrees. b. Do not allow sprayer pressure to exceed 600 psi. c. Spray the solution perpendicular (at 90 degrees) to the coil face. d. For evaporator coils, maintain a minimum clearance of 6" between the sprayer nozzle and the coil. For microchannel coils, optimum clearance between the sprayer nozzle and the microchannel coil is 1"-3”.

• Spray the leaving-airflow side of the coil first; then spray the opposite side of the coil. For evaporatorcoils, allow the cleaning solution to stand on the coil for five minutes.

• Rinse both sides of the coil with cool, clean water.

• Inspect both sides of the coil; if it still appears to be dirty, repeat Steps 6 and 7.

• Reinstall all of the components and panels removed in Step 1; then restore power to the unit.

• For evaporator coils, use a fin comb to straighten any coil fins which were inadvertently bent during the cleaning process.