FRIEDRICH QUIETMASTER KM21J30 (01) PDF Document

The model number for your FRIEDRICH QUIETMASTER KM21J30 provides specific information about the unit’s features. Here is a breakdown of the code:

1st DIGIT – FUNCTION

K = Straight Cool, Challenger or QuietMaster Series

2nd DIGIT – TYPE

S = Small Chassis

M = Medium Chassis

L = Large Chassis

3rd & 4th DIGITS – APPROXIMATE BTU/HR (Cooling)

This value represents the approximate cooling capacity in BTU/HR.

5th DIGIT – ALPHABETICAL MODIFIER

This is an alphabetical character for model modification.

6th DIGIT – VOLTAGE

1 = 115 Volts

2 = 230 Volts

3 = 230-208 Volts

7th DIGIT

0 = Straight Cool & Heat Pump Models

8th DIGIT

Represents a Major Change.

When applying and sizing a FRIEDRICH QUIETMASTER KM21J30 for cooling, it is crucial to consider all factors that may contribute to the heat loss or gain of the space. It is necessary to survey the space and calculate the load requirements before selecting the equipment size.

The load requirement can be determined using a standard “AHAM” Load Calculating Form. This form is easy to use and self-explanatory. You only need to insert the proper measurements and multiply by the given factors, then add the results for the total load requirement.

Cooling load requirements are generally based on comfortable air conditioning that does not require specific inside temperature and humidity conditions. The calculation is based on an outside design temperature of 95° FDB and 75° FWB. For other areas in the Continental United States, a correction factor can be applied based on the locality.

Follow these instructions which correspond to the numbered items on the form:

1. Multiply the square feet of window area for each exposure by the applicable factor. The window area is the area of the wall opening. Use the factor for “Inside Shades” or “Outside Awnings” as applicable. “Single Glass” includes single thickness windows, and “Double Glass” includes sealed airspace types, storm windows, and glass block. Enter only the number for the exposure with the largest load.

2. Multiply the total square feet of all windows in the room by the applicable factor.

3a. Multiply the total length (linear feet) of all walls exposed to the outside by the applicable factor. Doors are part of the wall. Calculate north-facing walls separately. An uninsulated frame wall or a masonry wall 8 inches or less is “Light Construction.” An insulated wall or masonry wall over 8 inches is “Heavy Construction.”

3b. Multiply the total length (linear feet) of all inside walls between the conditioned space and any unconditioned spaces by the given factor.

4. Multiply the total square feet of roof or ceiling area by the factor for the type of construction that best describes the application (use one line only).

5. Multiply the total square feet of floor area by the factor given. Disregard this if the floor is directly on the ground or over a basement.

6. Multiply the number of people who normally occupy the space by the factor given (use a minimum of 2 people).

7. Determine the total wattage for lights and electrical equipment (except the air conditioner) that will be in use. Multiply the total wattage by the factor given.

8. Multiply the total width (linear feet) of any doors or arches continually open to an unconditioned space by the applicable factor. NOTE: If the width is over 5 feet, consider both adjoining rooms as a single large room and recalculate.

9. Total the loads estimated for the foregoing 8 items.

10. Multiply the subtotal from item 9 by the proper correction factor from the map. The result is the total estimated design cooling load in BTU per hour.

For best results, select a unit with a cooling capacity rating as close as possible to the estimated load. A greatly oversized unit that operates intermittently will be much less satisfactory than a slightly undersized unit that operates more continuously.

The performance data is based on rating conditions of 80°F Room Air Temperature and 50% Relative Humidity with 95°F Outside Air Temperature at 40% Relative Humidity.

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

1. Terminal “C” and “S”: No continuity indicates an open winding, and the compressor must be replaced.

2. Terminal “C” and “R”: No continuity indicates an open winding, and the compressor must be replaced.

3. Terminal “R” and “S”: No continuity indicates an open winding, and the compressor must be replaced.

First, ensure the unit is disconnected from power. Use an ohmmeter set on its highest scale. Touch one lead to the compressor body (ensure a clean point of contact for a good connection) and the other probe in turn to each compressor terminal. If any reading is obtained, the compressor is grounded and must be replaced.

Compressor inefficiency is normally due to broken or damaged suction and/or discharge valves. To check for this condition, follow these steps:

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 performance test.

If the test shows:

A. Below normal high side pressure.

B. Above normal low side pressure.

C. Low temperature difference across the coil.

Then the compressor valves are faulty, and the compressor must be replaced.

To test an external thermal overload, which is located in the compressor terminal box, follow these steps after disconnecting power:

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 there is no continuity, it needs to be replaced.

Some compressors have an internal overload embedded in the motor windings. To check it, follow these steps:

1. With no power 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 it is not continuous, the compressor overload is open, and the compressor must be replaced. Note that the overload will automatically reset, but it may require several hours for the heat to dissipate.

To test the single-phase permanent split capacitor fan motor:

1. 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.

5. Apply “live” test cord probes to each of the remaining wires from the speed switch or system switch to test intermediate speeds.

To test the run capacitor, follow these steps:

1. Remove the capacitor from the unit after disconnecting power.

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

3. For a dual-rated capacitor, apply an ohmmeter lead to the common (C) terminal and the other probe to the compressor (HERM) terminal. A satisfactory capacitor will cause a deflection on the ohmmeter pointer, which then gradually moves back to infinity.

4. Reverse the leads of the probe and momentarily touch the capacitor terminals. The deflection of the pointer should be two times 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.

First, disconnect the leads from the control switch. Using an ohmmeter, there must be continuity between the following terminals for each position:

1. “Off” Position – no continuity between terminals.

2. “Lo Cool” Position – between terminals “L1” and “C”, “LO” and “MS”.

3. “Med Cool” Position – between terminals “L1” and “C”, “M” and “MS”.

4. “Hi Cool” Position – between terminals “L1” and “C”, “H” and “MS”.

5. “Fan Only” Position – between terminals “L1” and “2”.

If continuity is not present as described, the switch is faulty and should be replaced.

To test the thermostat, first disconnect power to the unit and remove the wires from the thermostat terminals. Then, perform the following checks:

1. Turn the thermostat to its coldest position. Check for continuity between the two terminals. There should be continuity.

2. Turn the thermostat to its warmest position. Check for continuity. The thermostat contacts should be open (no continuity).

NOTE: The temperature must be within the thermostat’s operating range (60°F to 92°F) to perform this test accurately.

No, you should not attempt to adjust the thermostat. Due to the sensitivity of the internal mechanism and the sophisticated equipment required to check calibration, it is recommended that the thermostat be replaced rather than recalibrated if it is not functioning correctly.

Disconnect power and remove the leads from the switch. Depress the switch to the function being tested and check for continuity with an ohmmeter.

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”.

If the switch fails either test, it should be replaced.

This procedure applies when replacing components like the compressor, condenser, evaporator, or repairing refrigerant leaks. It requires specialized equipment and should be performed by a qualified technician.

1. Recover the refrigerant from the system using an EPA-approved recovery system connected to 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 more 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 boost the pressure to 150 PSIG with dry nitrogen.

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

8. Reduce the system to zero gauge pressure.

9. Connect a vacuum pump to 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.

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

In the case of a motor compressor burnout, follow this special procedure:

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 equivalent 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 hermetic component replacement.

If the compressor on your FRIEDRICH QUIETMASTER KM21J30 does not run, check the following possible causes and perform the corresponding corrections:

Low voltage: Check for voltage at the compressor. 115 volt and 230 volt units will operate at 10% voltage variance.

Thermostat not set cold enough or inoperative: Set the thermostat to the coldest position. Test the thermostat and replace it if inoperative.

Compressor hums but cuts off on overload: This indicates a hard-starting compressor. Direct test the compressor. If it starts, add starting components.

Open or shorted compressor windings: Check for continuity and resistance. Replace the compressor if windings are faulty.

Open overload: Test the overload protector and replace it if inoperative.

Open capacitor: Test the capacitor and replace it if inoperative.

Inoperative system switch: Test for continuity in all positions. Replace if inoperative.

Broken, loose or incorrect wiring: Refer to the appropriate wiring diagram to check wiring.

If the fan motor on your FRIEDRICH QUIETMASTER KM21J30 does not run, check the following:

Inoperative system switch: Test the switch and replace it if inoperative.

Broken, loose or incorrect wiring: Refer to the applicable wiring diagram.

Open capacitor: Test the capacitor and replace it if inoperative.

Fan speed switch open: Test the switch and replace it if inoperative.

Inoperative fan motor: Test the fan motor and replace if inoperative. Be sure the internal overload has had time to reset.

If your FRIEDRICH QUIETMASTER KM21J30 is not cooling well, consider these possible causes and solutions:

Undersized unit: Refer to sizing charts to ensure the unit is appropriately sized for the space.

Thermostat open or inoperative: Set the thermostat to the coldest position. Test the thermostat and replace if necessary.

Dirty filter: Clean the filter as recommended in the Owner’s Manual.

Dirty or plugged condenser or evaporator coil: Use steam or detergents to clean the coils.

Poor air circulation in the area being cooled: Adjust the discharge air louvers. Use a high fan speed.

Fresh air or exhaust air door open on applicable models: Close the doors and instruct the customer on the use of this feature.

Low capacity – undercharge: Check for a leak and make the necessary repair.

Compressor not pumping properly: Check the amperage draw against the nameplate. If not conclusive, perform a pressure test.

If your FRIEDRICH QUIETMASTER KM21J30 will not start, investigate the following:

Fuse blown or circuit tripped: Replace the fuse or reset the breaker. If it repeats, check the fuse or breaker size and check for shorts in the unit wiring and components.

Power cord not plugged in: Plug in the power cord securely.

System switch in “Off” position: Set the switch to a cooling or fan setting.

Inoperative system switch: Test for continuity in each switch position and replace if faulty.

Loose or disconnected wiring at switch or other components: Check wiring and connections. Reconnect per the wiring diagram.

An evaporator coil freezing up can be caused by several issues. Here’s what to check:

Dirty filter: Clean the filter as recommended in the Owner’s Manual.

Restricted air flow: Check for a dirty or obstructed coil and clean it as required.

Inoperative thermostat: Test for a shorted thermostat or stuck contacts.

Short of refrigerant: De-ice the coil and check for a leak.

Inoperative fan motor: Test the fan motor and replace it if inoperative.

Partially restricted capillary: De-ice the coil. Check the temperature differential across the coil. Touch test the coil return bends for the same temperature. Test for low running current.

If the compressor runs continuously, check for the following:

Excessive heat load: The unit may be undersized. Test the cooling performance of the unit. You may need to replace it with a larger unit.

Restriction in line: Check for a partially iced coil. Check the temperature split across the coil.

Refrigerant leak: Check for oil at silver-soldered connections. Check for a partially iced coil and low running amperage.

Thermostat contacts stuck: Check the operation of the thermostat. Replace it if the contacts remain closed.

Thermostat incorrectly wired: Refer to the appropriate wiring diagram to verify connections.

If the thermostat is not cycling the unit off, consider these possibilities:

Thermostat contacts stuck: The thermostat needs to be replaced.

Thermostat set at coldest point: Turn the thermostat to a higher temperature setting to see if the unit cycles off.

Incorrect wiring: Refer to the appropriate wiring diagram to check the wiring.

Unit undersized for area to be cooled: Refer to the Sizing Chart to ensure the unit has adequate capacity for the room.

If your unit cycles on overload, investigate these potential issues:

Overload inoperative (opens too soon): Check the operation of the unit. Replace the overload if the system operation is satisfactory.

Compressor attempts to start before system pressures are equalized: Allow a minimum of two (2) minutes for pressures to equalize before attempting to restart. Instruct the customer about this waiting period.

Low or fluctuating voltage: Check the voltage with the unit operating. Check for other appliances on the circuit. The air conditioner should be on a separate, properly fused circuit.

Incorrect wiring: Refer to the appropriate wiring diagram.

Shorted or incorrect capacitor: Check by substituting a known good capacitor of the correct rating.

Restricted or low air flow through condenser coil: Check for proper fan speed or a blocked condenser.

Compressor running abnormally hot: Check for a kinked discharge line or a restricted condenser. Check the amperage.

If the thermostat fails to turn the unit on, check the following:

Loss of charge in thermostat bulb: Place a jumper across the thermostat terminals to check if the unit operates. If the unit operates, replace the thermostat.

Loose or broken parts in thermostat: Check the thermostat as described above. Replace if faulty.

Incorrect wiring: Refer to the appropriate wiring diagram to verify connections.

Noisy operation can be attributed to several factors:

Poorly installed unit: Refer to the Installation Instructions for proper installation procedures.

Fan blade striking chassis: Reposition and adjust the motor mount.

Compressor vibrating: Check that the compressor grommets have not deteriorated.

Improperly mounted or loose cabinet parts: Check that compressor mounting parts are not missing and that all cabinet parts are secure.

If water is leaking indoors, consider these causes:

Evaporator drain pan overflowing: Clean the obstructed drain trough.

Condensation forming on base pan: The evaporator drain pan may be broken or cracked. Reseal or replace it.

Poor installation resulting in rain entering room: Check the installation instructions and reseal as required.

Condensation on discharge grilles: This may be due to a dirty evaporator coil or very high humidity levels. Clean the coil.

Short cycling can be caused by the following:

Thermostat differential too narrow: Replace the thermostat.

Plenum gasket not sealing: A poor seal allows discharge air to short cycle the thermostat. Check the gasket and reposition or replace it.

Restricted coil or dirty filter: Clean the filter and advise the customer of periodic cleaning.

Thermostat bulb touching thermostat bulb support bracket (applicable models): Adjust the bulb bracket.

Prolonged off cycles can be due to:

Anticipator (resistor) wire disconnected at thermostat or system switch: Refer to the appropriate wiring diagram to correct the connection.

Anticipator (resistor) shorted or open (applicable models): Replace the thermostat block and resistor.

Partial loss of charge in thermostat bulb causing a wide differential: Replace the thermostat.

If you notice water leaking outside the unit, check these possible causes:

Evaporator drain pan cracked or obstructed: Repair, clean, or replace the drain pan as required.

Water in compressor area: Detach the shroud from the pan and coil. Clean and remove the old sealer. Reseal, reinstall, and check.

Obstructed condenser coil: Steam clean the condenser coil.

Fan blade and slinger ring improperly positioned: Adjust the fan blade to be 3/16 to 1/4″ from the condenser shroud. Adjust the fan motor mount to allow 3/16 to 1/4″ clearance between the condenser fan blade and base pan.

High indoor humidity can be addressed by checking the following:

Insufficient air circulation in the air conditioned area: Adjust the louvers for the best possible air circulation.

Oversized unit: Operate the unit in the “Fan-Auto (Moneysaver)” position to help reduce humidity.

Inadequate vapor barrier in building structure, particularly floors: This is a structural issue. Advise the customer to consult a building professional.