Carrier 90MA/MF/MU manual Condensers may require cleaning of water-deposited scale

BELT TENSION ADJUSTMENT - Shut off unit power

supply. Loosen fan motor from mounting bracket. Do not loosen motor mounting bracket from unit. Move fan motor up or down until proper belt tension is achieved (approximately 3/4-in. deflection with 8-pound tension at midpoint of belt span).

Lubrication - Fan motor and fan shaft bearings are lubricated for the life of the bearings. No re-lubrication is required

5.4Return--Air Filter

Inspect filters twice monthly and clean as required by operating conditions. Filter size and type are listed in Table 1, Table 3 or Table 2. To clean filters flush with hot water or steam or soak in a mild water solution of soap or detergent. Refer to filter manufacturer’s instructions as applicable. Do not operate unit without return-air filters in place.

5.5Condensate Drain

Clean the drain line and unit drain pan at the start of each cooling season. Check flow by pouring water into drain. Be sure trap is filled as shown in Figure 7 to maintain an air seal.

5.6Evaporator Coil

WARNING

Never reach into unit while fan is running. Lock open and tag unit disconnect before working on fan. Remove fuses and take them with you after noting this on tag.

Remove dirt and debris from evaporator coil as required by condition. Clean coil with a stiff brush, vacuum cleaner or compressed air. Use a fin comb of the correct tooth spacing (Refer toTable 1, Table 3 or Table 2 for coil fins/inch) when straightening mashed or bent coil fins.

5.7Water Regulating Valve

PREPARATION FOR OPERATION.

a.Open the water regulating valve inlet and outlet isola- tion valves.

b.Close the water regulating valve bypass valve.

ADJUSTMENT

a. The compressor discharge pressure is controlled by the water regulating valve and may be monitored by observing liquid line pressure.

NOTE

Adjustments to the water regulating valve must be made slowly, allowing ample time for re- sponse and stabilization.

b. Install a calibrated gauge at the liquid line service port. Operating liquid line range for R-22 units is 250 to 270 psig (1724 to 1862 kPa), for R-134a units is 155 to 180 psig (1069 to 1241 kPa) and for R-407C is 267 to 288 psig (1841 to 1986 kPa). If pressure read- ing is below operating range, rotate the square head adjusting screw counterclockwise; this will increase

spring tension, decrease water flow and increase pres- sure.

If pressure reading is above operating range, rotate the square head adjusting screw clockwise; this will decrease spring tension, increase water flow and de- crease pressure.

c. Only the water regulating valve opening point is ad- justable. The closing point is 3 to 7 psig below the opening point and is non-adjustable.

5.8Condenser

Condensers may require cleaning of water-deposited scale.

WARNING

Follow all Safety codes. Wear safety glasses and rubber gloves when using inhibited hy- drochloric acid solution.

Clean condensers with an inhibited hydrochloric acid solution. The acid can stain hands and clothing, attack concrete and, without inhibitor, can attack steel. Cover surroundings to guard against splashing. Vapors from vent pipe are not harmful, but take care to prevent liquid from being carried over by the gases.

Warm solution acts faster, but cold solution is just as effective if applied for a longer period.

Figure 9 Gravity Flow Method

GRAVITY FLOW METHOD

a.Disconnect condenser piping at unit, including isola- tion valves and water regulating valve.

b.Fill condenser as shown in Figure 9. Follow acid manufacturer’s instructions. When condenser is full, allow solution to remain overnight

c.Drain condenser and flush with clean water.

FORCED CIRCULATION METHOD

a.Disconnect condenser piping at unit, including isola- tion valves and water regulating valve.

b.Fill system as shown in Figure 10. Follow acid manufacturer’s instructions. Fully open vent pipe when filling system. The vent may be closed when system is full and pump is operating.

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