AirComm Corporation Cessna 182T T182T Maintenance Manual
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Products, Inc. CR-182-10 System Service Manual 21-50-00 Page 202 April 5, 2002 Figure 3 Correct expansion valve and sense bulb orientation
Products, Inc. CR-182-10 System Service Manual 21-50-00 Page 301 April 5, 2002 AIR-CONDITIONING SYSTEM SYSTEM SERVICING 1. GENERAL The air-conditioning system uses refrigerant R134a and the compressor lubricating oil used is Polyolester Oil viscosity grade (ISO) 68. No other refrigerant or compressor oil should be used. Refrigerant R134a is non-explosive, non-flammable, non-corrosive, has practically no odor, and is heavier than air. Although R134a is classified as a safe refrigerant, certain precautions must be observed to personnel and property when working with R134a refrigerant. WARNING: A. Liquid R134a, at normal atmospheric pressure and temperature, evaporates so quickly that it tends to freeze anything that it contacts. Care must be taken to prevent any liquid refrigerant from coming into contact with skin. B. Always wear safety goggles when servicing any part of the refrigerant system to prevent refrigerant from coming into contact with the eyes. C. The refrigerant containers and the air-conditioning components are under pressure. Do not expose the air-conditioning system or refrigerant containers to heat. Do not puncture the air-conditioning components or the refrigerant containers. CAUTION: Do not operate air-conditioning system with condenser air outlet blocked. 2. DISCHARGING SYSTEM A. General The air-conditioning system refrigerant must be discharged prior to disconnecting or removing any components in the refrigerant loop. Federal law prohibits discharging refrigerant into the atmosphere. Use only an R134a compatible recycling/recovery unit when discharging the air-conditioning system.
Products, Inc. CR-182-10 System Service Manual 21-50-00 Page 302 April 5, 2002 B. Tools and Equipment Designation Ref. No. Qty Remarks R134a Compatible Recycling/Recovery Unit Comm. Avail. 1 None C. Discharging Procedure 1) Connect R134a compatible recycling/recovery unit to the R134a service valves located near the evaporator installation on the right hand side of the aircraft. 2) Empty the recycling/recovery unit of oil. 3) Discharge the air-conditioning system in accordance with the recovery units instructions. 4) Empty the oil from the recycling/recovery unit. Note the amount of oil removed during the system discharge. This amount of oil must be added to the air-conditioning system prior to charging. Only use polyolester oil viscosity grade ISO 68. 3. EVACUATING SYSTEM A. General The air-conditioning system must be evacuated prior to charging the system with refrigerant. Evacuating the system removes any moisture and air that may be in the system. Use only an R134a compatible recycling/recovery unit when evacuating the air-conditioning system. B. Tools and Equipment Designation Ref. No. Qty Remarks R134a Compatible Recycling/Recovery Unit Comm. Avail. 1 None
Products, Inc. CR-182-10 System Service Manual 21-50-00 Page 303 April 5, 2002 C. Evacuating Procedure 1) Connect R134a compatible recycling/recovery unit to the R134a service valves on the aircrafts air-conditioning system. 2) Empty the oil from the recycling/recovery unit. 3) Evacuate the air-conditioning system in accordance with the recovery units instructions for a minimum of 15 minutes. 4) Empty the oil from the recycling/recovery unit. Note the amount of oil removed during the vacuum. This amount of oil must be added to the air- conditioning system prior to charging. Only use polyolester oil viscosity grade ISO 68. 5) Once the air-conditioning system has been evacuated, it is then ready for charging with new/recycled R134a refrigerant. 4. CHARGING SYSTEM A. General Use only R134a refrigerant when charging air-conditioning system. Federal law prohibits discharging refrigerant into the atmosphere. Use only R134a compatible recycling/recovery unit when charging the air-conditioning system. B. Tools and Equipment Designation Ref. No. Qty Remarks R134a Compatible Recycling/Recovery Unit Comm. Avail. 1 None R134a refrigerant Comm. Avail 2.5 lbs. None Polyolester Oil Comm. Avail 5 fl. oz. Viscosity ISO 68 C. Charging Procedure 1) Connect R134a compatible recycling/recovery unit to the R134a service valves on the aircrafts air-conditioning system. If recovery unit does not have pressure gauges, connect service pressure gauges to air-conditioning system. 2) Evacuate the air-conditioning system for 15 minutes in accordance with the instructions in this report. 3) Close the low side and open the high side on the recycling/recovery unit. 4) Add polyolester oil viscosity ISO 68 to the high side service tee using the refrigerant recycling/recovery unit while the system is under a vacuum.
Products, Inc. CR-182-10 System Service Manual 21-50-00 Page 304 April 5, 2002 NOTE: Adding refrigerant or oil from the recycling/recovery unit directly to the low-pressure service tee will allow liquid refrigerant or oil to enter the compressor. The compressor is only designed to compressor gas refrigerant, and liquid refrigerant or oil may damage/destroy the compressor. Always close the low side of the recycling/recovery unit during charging. 5) Charge the air-conditioning system in accordance with the recovery units instructions except as noted 6) If bubbles are present at the sight glass after the system has been running for a minimum of 5 minutes, add refrigerant as necessary.
Products, Inc. CR-182-10 System Service Manual 21-50-00 Page 601 April 5, 2002 AIR-CONDITIONING SYSTEM INSPECTION/CHECKS 1. GENERAL General service procedures are provided to keep the air-conditioning system operating at peak efficiency. Procedures are provided for inspection intervals, refrigerant charge inspection, refrigerant leak inspection, and compressor oil level inspection. CAUTION: Do not operate air-conditioning system with condenser air outlet blocked. A. Tools and Equipment Designation Ref. No. Qty Remarks Service Pressure Gage Comm. Avail. 1 None Electronic Leak Detector Comm. Avail. A/R Type H-10G Polyolester Oil Comm. Avail. A/R Viscosity ISO 68 2. INSPECTION INTERVALS A. General Periodic inspections of the air-conditioning system will keep the system operating at peak efficiency. The inspections are simple visual inspections requiring a minimal amount of time. B. Inspection Intervals *Or every annual inspection, which ever comes first. ITEM INSPECT FOR INTERVAL ACTION AIR-CONDITIONING SYSTEM COMPONENTS DIRT , DAMAGE EVERY 600 HOURS*CLEAN OR REPLACE COMPONENTS AS NECESSARY COMPRESSOR BELT TENSION , WEARWITHIN 5 HOURS OF INSTALLING A NEW BELT, THEN EVERY 600 HOURS*TENSION OR REPLACE AS NECESSARY SIGHT GLASSPROPER REFRIGERANT LEVELWHEN PROBLEM IS SUSPECTED*DISCHARGE/CHARGE AS NECESSARY EVAPORATOR AND CONDENSER COILS DIRT EVERY 600 HOURS*CLEAN OR REPLACE AS NECESSARY
Products, Inc.
CR-182-10 System Service Manual
21-50-00
Page 602
April 5, 2002
3. REFRIGERANT LEVEL INSPECTION
To be performed when improper refrigerant charge is suspected.
A. Select air-conditioning system switch to AIR COND position.
B. Set the cabin temperature knob to the MAX position.
C. Set the fan speed knob to the HI position.
D. Run system for five (5) minutes minimum.
E. Check that the receiver/drier inlet and outlet fitting temperatures are the same.
If the outlet is considerably colder, the receiver/drier screen is may be clogged
and may need replacement.
F. Check the sight glass for bubbles. No bubbles should be visible after 5 minutes
of operation.
NOTE: The refrigerant bubbles are more difficult to see at ambient
temperatures below 65ºF. Always re-check refrigerant level when
ambient temperature is above 65ºF for proper level.
G. Add/Remove refrigerant as necessary.
4. REFRIGERANT SYSTEM LEAKAGE INSPECTION
To be performed when refrigerant leak is suspected.
A. The system leakage check is to be performed in an area with an ambient
temperature of 65ºF or above.
B. Install service pressure gage to low and high pressure R134a service valves.
C. On systems that have not been operated for 2 weeks or longer, operate the
system for a minimum of 15 minutes. This will lubricate the compressor shaft
seal and ensure a more accurate leakage check of the shaft seal.
D. With the system off, and using a type H-10G electronic leak detector or
equivalent, check all connections, compressor shaft seal, and fabricated
components for leakage. No leakage is acceptable.
5. COMPRESSOR OIL LEVEL CHECK
NOTE: It is not necessary to check the compressor oil level during routine
maintenance. It only needs to be checked when a system component
is replaced or when incorrect oil level is suspected. Only polyolester oil
viscosity grade ISO 68 should be used.
1. Operate air-conditioning system for 10 minutes. This will collect as
much oil as possible in the compressor.
2. Discharge air-conditioning system in accordance with the discharging
instructions in this manual.
3. Remove either discharge or suction port hose fitting.
4. Remove oil drain plug and allow all oil to drain.
5. Add 5 ounces of oil to the compressor.
6. Clean oil drain area and install drain plug. Torque to 6 - 9 ft-lbs.
Products, Inc. CR-182-10 System Service Manual 21-50-00 Page 603 April 5, 2002 7. Install hose fitting. 8. Charge air-conditioning system in accordance with the charging instructions in this manual.
Products, Inc. CR-182-10 System Service Manual 21-50-01 Page 1 April 5, 2002 ELECTRICAL DESCRIPTION AND OPERATION 1. GENERAL The electrical system of the Cessna 182 air-conditioning system operates from the main 28 VDC buss. The major components of the electrical system are: Evaporator Blower: Blows cold air into the cabin. Condenser Blower: Removes heat from the refrigerant Compressor Clutch: Engages/disengages the compressor 2. SAFETY FEATURES During certain flight configurations the compressor clutch and condenser blower are disabled to supply electrical power to more critical systems. Depending on the aircraft model and type, automatic load shedding removes power to the compressor clutch and condenser blower when high load systems are engaged. The evaporator blower will remain available to re-circulate cockpit air during all flight configurations. Before electrical current reaches the compressor clutch it passes through the JBS2020- 5 Pressure Switch and the JBS60-2 Freeze Switch. In the event of excessive refrigerant pressure during flight (caused by failed or blocked condenser blower) or inadequate refrigerant pressure (caused by a leak in the plumbing) the JBS2020-5 pressure switch will open and disable the compressor clutch. In the event of extremely low temperature air exiting the evaporator (which may cause the coil to freeze) the JBS60-2 Freeze Switch will open and disable the compressor clutch. 3. TEMPERATURE CONTROLLER OPERATION The Cessna 182 air-conditioning system is equipped with a variable temperature control on the pilot’s instrument panel. ES52126-1 thermistors vary in resistance as temperature changes and are placed at the inlet of the evaporator coil. The ES62117-1 Temperature Controller measures the resistance from the thermistors and compares that resistance with the cooling adjustment knob setting. The temperature controller then energizes and de-energizes the ES56128-1 Relay which engages and disengages the compressor clutch. Example: The aircraft operator set the temperature control knob for 70ºF (medium cooling). The temperature controller measures the resistance of the thermistors and determines that the air entering the evaporator is 68ºF. The temperature controller energizes the normally closed relay to remove power to the clutch. Since the compressor is not
Products, Inc. CR-182-10 System Service Manual 21-50-01 Page 2 April 5, 2002 turning, the air-conditioning is not accomplishing any cooling and the air into the evaporator increases in temperature to 72ºF. The temperature controller measures the resistance of the thermistors and determines that the air temperature is too high. The temperature controller de-energizes the normally closed relay to send power back to the clutch. The compressor now turns and lowers the air temperature of the cockpit air. This will continue to keep the air at the evaporator inlet temperature at 70ºF.