FRIEDRICH QUIETMASTER KS12J10 (01) PDF Document

Rating Conditions: 80°F. Room Air Temperature and 50% Relative Humidity with 95°F. Outside Air Temperature at 40% Relative Humidity.

First, disconnect electrical power to the unit before servicing. Remove the compressor terminal box cover and disconnect wires from the terminals. Using an ohmmeter, check for continuity across the following terminals:

1. Terminal “C” and “S” – no continuity means there is an open winding and the compressor must be replaced.

2. Terminal “C” and “R” – no continuity means there is an open winding and the compressor must be replaced.

3. Terminal “R” and “S” – no continuity means there is an open winding and the compressor must be replaced.

First, disconnect electrical power to the unit before servicing. Use an ohmmeter set on its highest scale. Touch one lead to the compressor body, ensuring a clean point of contact for a good connection. Touch the other probe in turn to each compressor terminal. If a reading is obtained, the compressor is grounded and must be replaced.

Compressor inefficiency is typically caused by broken or damaged suction and/or discharge valves, which reduces the compressor’s ability to pump refrigerant gas. To check for this condition:

1. Install a piercing valve on the suction and discharge or liquid process tube.

2. Attach gauges to the high and low sides of the system.

3. Start the system and run a “cooling or heating performance test.”

If the test shows A) below normal high side pressure, B) above normal low side pressure, and C) low temperature difference across the coil, the compressor valves are faulty and the compressor must be replaced.

To test the external thermal overload on models equipped with one:

1. Remove the overload.

2. Allow time for the overload to reset before attempting to test.

3. Apply ohmmeter probes to the terminals on the overload wires. There should be continuity through the overload if it is functioning correctly.

The internal overload is embedded in the motor windings. To check it:

1. With no power connected to the unit, remove the leads from the compressor terminals.

2. Using an ohmmeter, test for continuity between terminals C-S and C-R. If there is no continuity, the compressor overload is open, and the compressor must be replaced.

To test the fan motor:

1. First, determine that the capacitor is serviceable.

2. Disconnect the fan motor wires from the fan speed switch or system switch.

3. Apply “live” test cord probes to the black wire and the common terminal of the capacitor. The motor should run at high speed.

4. Apply “live” test cord probes to the red wire and the common terminal of the capacitor. The motor should run at low speed.

To test the run capacitor:

1. Remove the capacitor from the unit.

2. Check for visual damage such as bulges, cracks, or leaks.

3. For a dual-rated capacitor, apply one ohmmeter lead to the common (C) terminal and the other probe to the compressor (HERM) terminal. A satisfactory capacitor will cause the ohmmeter’s pointer to deflect and then gradually move back to infinity.

4. Reverse the leads of the probe and momentarily touch the capacitor terminals. The pointer’s deflection should be twice that of the first check if the capacitor is good.

5. Repeat steps 3 and 4 to check the fan motor side of the capacitor.

NOTE: A shorted capacitor will indicate a low resistance (pointer moves to “0” and stays). An open capacitor will show no movement of the pointer at all.

First, disconnect the leads from the control switch. Then, check for continuity between the terminals for each position:

“Off” Position: No continuity between any terminals.

“Lo Cool” Position: Continuity between terminals “L1” and “C”, and between “LO” and “MS”.

“Med Cool” Position: Continuity between terminals “L1” and “C”, and between “M” and “MS”.

“Hi Cool” Position: Continuity between terminals “L1” and “C”, and between “H” and “MS”.

“Fan Only” Position: Continuity between terminals “L1” and “2”.

Remove the wires from the thermostat. Turn the thermostat to its coldest position and check for continuity between the two terminals. Next, turn the thermostat to its warmest position and check that the thermostat contacts open (no continuity). NOTE: The ambient temperature must be within the thermostat’s operating range of 60°F (± 2°) to 92°F (± 4°) for an accurate test.

No attempt should be made to adjust the thermostat. Due to the sensitivity of the internal mechanism and the sophisticated equipment required to check the calibration, it is suggested that the thermostat be replaced rather than calibrated.

Disconnect the leads from the switch. Depress the switch to the function you are testing.

1. When YES is depressed, there should be continuity between terminals “1” and “2”.

2. When NO is depressed, there should be continuity between terminals “2” and “3”.

The following procedure applies when replacing components in the sealed refrigeration circuit (e.g., compressor, condenser, evaporator, capillary tube):

1. Recover the refrigerant from the system at the process tube.

2. Cut the process tube below the pinch off on the suction side of the compressor.

3. Connect a nitrogen tank to the suction process tube.

4. Drift dry nitrogen through the system and unsolder the most distant connection first (e.g., filter drier).

5. Replace the inoperative component and always install a new filter drier. Drift dry nitrogen through the system while making these connections.

6. Pressurize the system to 30 PSIG with proper refrigerant and then boost the pressure to 150 PSIG with dry nitrogen.

7. Leak test the complete system with an electronic halogen leak detector and correct any leaks found.

8. Reduce the system to zero gauge pressure.

9. Connect a vacuum pump to both the high and low sides of the system using deep vacuum hoses.

10. Evacuate the system to a maximum absolute holding pressure of 200 microns or less.

11. Break the vacuum by charging the system from the high side with the correct amount of specified refrigerant. This prevents boiling the oil out of the crankcase.

12. Restart the unit several times, allowing pressures to stabilize. Pinch off the process tubes, cut and solder the ends. Remove the pinch off tool and leak check the process tube ends.

1. Recover all refrigerant and oil from the system.

2. Remove the compressor, capillary tube, and filter drier from the system.

3. Flush the evaporator, condenser, and all connecting tubing with dry nitrogen or an equivalent substance to remove all contamination. Inspect the suction and discharge lines for carbon deposits and clean them if necessary.

4. Reassemble the system, including a new drier strainer and capillary tube.

5. Proceed with processing as outlined under the standard hermetic component replacement procedure.

1. Due to the spinning motion of the rotary compressor, the mounts are critical. If you notice vibration, check the mounts carefully.

2. The electrical terminals on a rotary compressor are in a different order than on reciprocating compressors. The terminal markings are on the cover gasket. Use your wiring diagram to ensure correct connections.

The refrigerant charge is extremely critical and must be measured carefully to be as exact as possible to the nameplate charge. The correct method for charging is to introduce liquid refrigerant into the high side of the system while the unit is off. Then, start the compressor and enter the balance of the charge as gas only into the low side. Introducing liquid directly into the low side without a capillary tube will cause damage to the discharge valve of the rotary compressor.