HVAC SYSTEM - GENERAL SERVICING

• HEADINGS
  • USING R-12 & R-134a REFRIGERANT
    • HANDLING/SAFETY PRECAUTIONS
    • IDENTIFYING R-134a SYSTEMS & COMPONENTS
      • Fittings & "O" Rings
      • Underhood A/C Specification Labels
    • REFRIGERANT OILS
      • Ford
  • SYSTEM SERVICE VALVES
    • SCHRADER-TYPE VALVES
    • SPECIAL VALVE CONNECTORS
    • R-134a SERVICE VALVES/PORTS
    • SERVICE VALVE LOCATIONS
  • SERVICE EQUIPMENT
  • MANIFOLD GAUGE SET
    • Low-Side Gauge
    • High-Side Gauge
    • CONNECTING GAUGE SET
      • Schrader-Type Valves
    • PURGING TEST HOSES
    • STABILIZING A/C SYSTEM
  • PRESSURE-TEMPERATURE RELATIONSHIP
  • PRESSURE GAUGE READINGS
  • ORIFICE TUBE REPLACEMENT
    • FORD MOTOR CO.
      • Orifice Tube Replacement
      • Orifice Tube Kit
  • REFRIGERANT RECOVERY/RECYCLING
    • FORD MOTOR CO.
  • FLUSHING A/C SYSTEM
    • FORD MOTOR CO.
  • EVACUATING A/C SYSTEM
    • FORD MOTOR CO.
  • CHARGING A/C SYSTEM
    • FORD MOTOR CO.
  • LEAK TESTING
    • TYPES OF LEAK DETECTORS
      • Bubble Solution Detector
      • Dye Solution
      • Electronic Detector
    • PREPARATION FOR LEAK TESTING
    • BUBBLE DETECTOR LEAK TESTING PROCEDURE
    • ELECTRONIC LEAK TESTING PROCEDURE
    • DYE SOLUTION LEAK TESTING PROCEDURES
• FIGURES
  • Fig. 1: Identifying R-134a Service Ports (Typical)
  • Fig. 2: Underhood Refrigerant Identification Label (Ford)
  • Fig. 3: Schrader Service Valve (Compressor Location Shown)
  • Fig. 4: Flexible High Side Adapter
  • Fig. 5: R-134a Service Couplings (Typical)
  • Fig. 6: Normally Functioning R-134a A/C System
  • Fig. 7: Some Moisture In R-134a System
  • Fig. 8: Low R-134a Charge
  • Fig. 9: Poor R-134a Refrigerant Circulation
  • Fig. 10: No R-134a Refrigerant Circulation
  • Fig. 11: Insufficient Cooling Of Condenser Or R-134a Refrigerant Overcharge
  • Fig. 12: Air In R-134a System
  • Fig. 13: Expansion Valve Improperly Mounted Or Heat Sensing Tube Defective (Opening Too Wide)
  • Fig. 14: Compressor Malfunction
  • Fig. 15: Removing Orifice Tube
  • Fig. 16: Removing Broken Orifice Tube
  • Fig. 17: Determining Orifice Tube Location (Ford)
  • Fig. 18: Installing Orifice Tube Kit (Ford)
  • Fig. 19: Permanent A/C System Filters (Ford)
  • Fig. 20: Temporary Pancake Filter (Ford)
  • Fig. 21: Electronic Leak Detector
• TABLES
  • SERVICE VALVE LOCATIONS (CARS)
  • SERVICE VALVE LOCATIONS (TRUCKS & VANS)
  • R-134A PRESSURE-TEMPERATURE RELATIONSHIP

A/C SYSTEM GENERAL SERVICING

1996 GENERAL SERVICING General Servicing Procedures

USING R-12 & R-134a REFRIGERANT

HANDLING/SAFETY PRECAUTIONS

1. Always work in a well-ventilated, clean area. Refrigerant (R-12 orR-134a) is colorless and invisible as a gas. Refrigerant is heavier than oxygen and will displace oxygen in a confined area. Avoid breathing refrigerant vapors. Exposure may irritate eyes, nose and throat.
2. Always wear eye protection when working around A/C system and refrigerant. The system's high pressure can cause severe injury to eyes and skin if a hose were to burst. If necessary, wear rubber gloves or other protective clothing.
3. Refrigerant evaporates quickly when exposed to atmosphere, freezing anything it contacts. If liquid refrigerant contacts eyes or skin (frostbite), DO NOT rub eyes or skin. Immediately flush affected area with cool water for 15 minutes and consult a doctor or hospital.
4. Never use R-134a in combination with compressed air for leak testing. Pressurized R-134a in the presence of oxygen (air concentrations greater than 60 percent by volume) may form a combustible mixture. DO NOT introduce compressed air into R-134a containers (full or empty), A/C system components, or service equipment.
5. DO NOT expose A/C system components to high temperatures (steam cleaning for example), as excessive heat will cause refrigerant system pressure to increase. Never expose refrigerant directly to open flame. If refrigerant needs to be warmed, place bottom of refrigerant tank in warm water. Water temperature MUST NOT exceed 125°F (52°C).

   CAUTION:

   When R-134a is exposed to an open flame, drawn into engine, or detected with a Halide (propane) leak tester, a poisonous gas is formed. Keep work areas well ventilated.

6. Use care when handling refrigerant containers. DO NOT drop, strike, puncture, or incinerate containers. Use Department Of Transportation (DOT) approved (DOT 4BW or DOT 4BA) refrigerant containers.
7. Never overfill refrigerant containers. The safe filling level of a refrigerant container MUST NOT exceed 60% of the container's gross weight rating. Store refrigerant containers at temperatures less than 125°F (52°C).
8. Freon (R-12) is sold and stored in White colored containers, while R-134a refrigerant is sold and stored in 30- or 50-pound Light Blue containers.
9. Refrigerant R-12 and R-134a must never be mixed, as they and their desiccants and lubricants are not compatible. If the refrigerants are mixed, system cross-contamination or A/C system component failure may occur. Always use separate servicing and refrigerant recovery/recycling equipment.
10. Read and follow equipment manufacturer's instructions for all service equipment to be used. The Material Safety Data Sheet (MSDS), provided by refrigerant manufacturer/supplier, contains valuable information regarding the safe handling of refrigerants.

IDENTIFYING R-134a SYSTEMS & COMPONENTS

To prevent refrigerant cross-contamination, use following methods to identify R-134a based systems and components.

Fittings & "O" Rings

All R-134a based A/C systems use 1/2" - 16 ACME threaded fittings (identifiable by square threads) and quick-connect service ports. See Fig. 1 .

Fig. 1: Identifying R-134a Service Ports (Typical)

Underhood A/C Specification Labels

Most R-134a based systems will be identified through the use of underhood labels with R-134a refrigerant clearly printed on labels. The underhood label used on Ford Motor Co. vehicles is Yellow . See Fig. 2 . Most manufacturers will identify refrigerant ty pe with labels affixed to compressor. Before servicing an A/C system, always determine which refrigerant is being used.

Fig. 2: Underhood Refrigerant Identification Label (Ford)
Courtesy of FORD MOTOR CO.

REFRIGERANT OILS

Refrigerant R-12 based systems use mineral oil, while R-134a systems use synthetic Polyalkylene Glycol (PAG) oils. Using a mineral oil based lubricant with R-134a will result in A/C compressor failure due to lack of proper lubrication.

Following are the most common R-134a refrigerant oils used by most domestic vehicles:

Ford

On all models, use YN-12B PAG Refrigerant Oil (Part No. F2AZ-19577-A).

SYSTEM SERVICE VALVES

SCHRADER-TYPE VALVES

NOTE:

Although similar in construction and operation to a tire valve, NEVER replace a Schrader-type valve with a tire valve.

Schrader valve is similar in construction and operation to a tire valve. See Fig. 3 . When a test gauge hose is attached (hose has bu ilt-in valve core depressor), Schrader stem is pushed inward to the open position and allows system pressure to reach the gauge.

If test hose being used does not have a built-in core depressor, an adapter must be used. Never attach hoses or adapters to a Schrader valve unless it is first connected to manifold gauge set.

Fig. 3: Schrader Service Valve (Compressor Location Shown)

SPECIAL VALVE CONNECTORS

On some vehicles, thread size on high-side service valve (3/8" - 24 threads) is different from thread size on low-side service valve (7/16" - 20 threads). Special adapters are required to make this connection. See Fig. 4 . These adapters are availa ble in 45-degree and 90-degree angles in addition to straight-fixed and flexible adapters.

Some Ford Motor Co. systems require installation of Adapter (D81L-19703-A) on discharge line for high-side gauge installation. For low-side gauge installation, it may be necessary to remove pressure switch from accumulator. Install Adapter (D87P-19703-A) between accumulator and pressure switch. Connect gauge to adapter.

Fig. 4: Flexible High Side Adapter

R-134a SERVICE VALVES/PORTS

All vehicles with R-134a refrigerant use quick-disconnect service valves/ports. All R-134a systems use quick-disconnect fittings with sealing caps that thread into inside of service port instead of onto outside of service port.

The high side uses a large service port, and the low side uses a small service port. See Fig. 1 . The R-134a service ports have in ternal metric threads to help prevent the accidental connection of R-12 servicing equipment.

There are 2 types of quick-disconnect service couplings which can be used on R-134a systems. One type of service coupling depresses service port valve when connection is made. The other type connects onto service port but will not depress service port valve until a knob is rotated. See Fig. 5 .

Fig. 5: R-134a Service Couplings (Typical)

SERVICE VALVE LOCATIONS

For service valve locations, refer to the appropriate table. Refer to the following:

• Cars, see: SERVICE VALVE LOCATIONS (CARS) .
• Trucks & Vans, see: SERVICE VALVE LOCATIONS (TRUCKS & VANS) .

SERVICE VALVE LOCATIONS (CARS)

Vehicle		High	Low
Continental		(5)	(6)
Contour & Mystique
2.0L Engine		(7)	(8)
2.5L Engine		(7)	(9)
Cougar & Thunderbird		(7)	(3)
Crown Victoria, Grand Marquis & Town Car		(7)	(3)
Escort & Tracer		(1)	(2)
Mark VIII		(7)	(9)
Mustang		(7)	(3)
Probe		(4)	(3)
Sable & Taurus		(7)	(9)
(1) In discharge (high pressure) line, near condenser. (2) In suction (low pressure) line. (3) On accumulator-drier or filter-drier. (4) On liquid line extension, in front of condenser. (5) On condenser to evaporator tube, to right of radiator. In the stowed position, it is clipped to the condenser. (6) On suction line, at evaporator core outlet tube. (7) On A/C manifold and tube, between A/C compressor and condenser. (8) On suction line, between evaporator core and accumulator-drier. (9) On A/C manifold and tube, between A/C compressor and accumulator-drier.

SERVICE VALVE LOCATIONS (TRUCKS & VANS)

Vehicle	High	Low
Aerostar, Explorer & Ranger	(1)	(4)
Bronco & "F" Series	(1)	(2)
"E" Series	(1)	(4)
Villager	(6)	(7)
Windstar	(5)	(3)
(1) In discharge (high pressure) line, near condenser. (2) In suction (low pressure) line between evaporator and compressor. (3) In suction (low pressure) line, near receiver-drier. (4) On accumulator-drier. (5) On A/C compressor plumbing or manifold. (6) On high pressure line extension from A/C compressor. (7) On suction line, near accumulator-drier.

SERVICE EQUIPMENT

Because R-134a is not interchangeable with R-12, separate sets of hoses, gauges and recovery/recycling equipment are required to service vehicles. This is necessary to avoid cross-contamination and damaging system.

All equipment used to service systems using R-134a must meet SAE standard J1991. The service hoses on the manifold gauge set must have manual (turn wheel) or automatic back-flow valves at the service port connector ends. This will prevent refrigerant from being released into the atmosphere.

For identification purposes, R-134a service hoses must have a Black stripe along their length and be clearly labeled SAE J2196/134a. The low pressure test hose is Blue with a Black stripe. The high pressure test hose is Red with a Black stripe. The center test hose is Yellow with a Black stripe.

NOTE:

Refrigerant R-12 service hoses will ONLY be labeled SAE J2196.

R-134a manifold gauge sets can be identified by one or all of the following:

• Labeled FOR USE WITH R-134a on set.
• Labeled HFC-134 or R-134a on gauge face.
• Light Blue color on gauge face.

In addition, pressure/temperature scales on R-134a gauge sets are different from R-12 manifold gauge sets.

MANIFOLD GAUGE SET

A manifold gauge set is used to determine system's high-side and low-side pressures, correct refrigerant charge, system diagnosis and operating efficiency. High (discharge) and low (suction) pressures must be compared to determine system operation. Manifold gauge sets for the 2 refrigerant types are basically the same except for fittings at ends of hoses. Fittings are different to ensure connection only to appropriate refrigerant system.

Low-Side Gauge

Low-side gauge, which may have a Blue identifying feature, is used to measure low-side (suction) pressure. Low-side gauge is also called a compound gauge because it can measure pressure and vacuum. Pressure scale ranges from 0 to 150 psi; vacuum scale ranges from 0 to 30 in. Hg.

High-Side Gauge

High-side gauge, which may have a Red identifying feature, is used to measure high-side (discharge) pressure. Gauge scale ranges from 0 to 500 psi.

CONNECTING GAUGE SET

NOTE:

R-134a quick disconnect service couplings are connected in the same sequence as Schrader-type service valves.

Schrader-Type Valves

1. Put on safety goggles, and cover vehicle's fender. Slowly remove protective caps from Schrader valves to check for leaky valves.

   CAUTION:

   Ensure hand valves on manifold gauge set and the hose-end shutoff valves are closed before attaching test hoses to Schrader valves.

2. Ensure service hoses are equipped with valve core depressor to match Schrader valve. If not, install special adapters for this purpose. If the high-side service hose connector will not fit on high-side Schrader valve, a special adapter must be used. See SPECIAL VALVE CONNECTORS .
3. Ensure both manifold gauge hand valves are closed. Connect low-side service hose to low-side (suction) service valve, and finger tighten connections. Connect high-side service hose to high-side (discharge) service valve, and finger tighten connections.

NOTE:

After test gauges are installed, test hoses must be purged of all air before proceeding with testing.

PURGING TEST HOSES

1. Ensure high-side and low-side hoses are properly connected to service valves, and all hose connections are tight. Place a clean shop towel over end of center service hose.
2. Purge high-side test hose by opening hand valve on high-side gauge for 3-5 seconds. This allows system's refrigerant to force air through test hoses and out of center service hose into the shop towel. Immediately close high-side gauge hand valve.
3. Purge low-side test hose in the same manner using hand valve of low-side gauge. Close hand valve after 3-5 seconds. Purging of test hoses is now complete, and system is ready for testing.

NOTE:

If manifold gauge set is to be used in conjunction with refrigerant recovery/recycling equipment, use instructions provided with the recovery/recycling equipment to properly purge test hoses.

STABILIZING A/C SYSTEM

1. Once manifold gauge set is attached to system and test hoses have been purged, system is ready for testing. Place all test hoses, gauge set and other equipment away from all moving parts of engine.
2. Start engine, and turn A/C controls to maximum cooling position (full cold or "MAX A/C"). Set blower fan on high speed. Open doors and/or windows. Operate system for 5-10 minutes. System should now be stabilized and ready for test readings.

PRESSURE-TEMPERATURE RELATIONSHIP

A refrigerant, when confined in an enclosed space, increases in pressure as the temperature increases. Conversely, if the temperature is lowered, the pressure also decreases.

Depending on temperature, a corresponding pressure will exist in a such an enclosed space. For example, at 70°F (21.1°C), a gauge will indicate about 71.0 psi (5.0 kg/cm² ). Refer to the R-134A PRESSURE-TEMPERATURE RELATIONSHIP table to see this relationship.

R-134A PRESSURE-TEMPERATURE RELATIONSHIP

Temperature °F (°C)	(1) psi (kg/cm2 )
20 (-6.7)	18 (1.3)
30 (-1.1)	26 (1.8)
40 (4.4)	35 (2.5)
45 (7.2)	40 (2.8)
50 (10.0)	45 (3.2)
55 (12.8)	51 (3.6)
60 (15.6)	57 (4.0)
65 (18.3)	64 (4.5)
70 (21.1)	71 (5.0)
75 (23.9)	79 (5.6)
80 (26.7)	87 (6.1)
85 (29.4)	95 (6.7)
90 (32.2)	104 (7.3)
95 (35.0)	114 (8.0)
100 (37.8)	124 (8.7)
110 (43.3)	147 (10.3)
120 (48.9)	171 (12.0)
130 (54.4)	199 (14.0)
140 (60.0)	229 (16.1)
150 (65.6)	263 (18.5)
160 (71.1)	300 (21.1)
(1) Pressure readings are provided as a general guideline and may not represent actual readings.

PRESSURE GAUGE READINGS

The pressure gauge readings used represent an expansion valve type system using a Nippondenso 10-cylinder compressor. See Fig. 6 -Fig. 14 . Gauge indications will vary depending on system configuration and compressor application.

Temperature and humidity, as well as other factors, affect pressure gauge readings. Compared to R-12 systems, pressure readings on R-134a systems are generally lower for low-side pressure and higher for high-side pressure. Pressure gauge readings should be used only as a guide.

Fig. 6: Normally Functioning R-134a A/C System

Fig. 7: Some Moisture In R-134a System

Fig. 8: Low R-134a Charge

Fig. 9: Poor R-134a Refrigerant Circulation

Fig. 10: No R-134a Refrigerant Circulation

Fig. 11: Insufficient Cooling Of Condenser Or R-134a Refrigerant Overcharge

Fig. 12: Air In R-134a System

Fig. 13: Expansion Valve Improperly Mounted Or Heat Sensing Tube Defective (Opening Too Wide)

Fig. 14: Compressor Malfunction

ORIFICE TUBE REPLACEMENT

FORD MOTOR CO.

NOTE:

Ford evaporator core orifice tube is located in evaporator inlet pipe. Replace orifice tube whenever compressor is replaced.

Orifice Tube Replacement

1. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Disconnect high pressure line. Remove and discard "O" rings. Pour a small amount of refrigerant oil into inlet to lubricate "O" rings.
2. Insert the orifice tube remover/installer into the tube. See Fig. 15 . Turn tool to right to engage tangs on tube. Turn tool nut to slowly pull orifice tube out. If it breaks off when removal is attempted, use broken orifice tube extractor to pull the broken section out. See Fig. 16 .
3. Ensure new orifice tube is fitted with new "O" ring(s) lubricated with clean refrigerant oil. Insert tube with short end toward evaporator until seated. Reconnect high pressure line.

NOTE:

If broken orifice tube extractor fails to remove broken orifice tube, install orifice tube kit. See ORIFICE TUBE KIT heading below.

Fig. 15: Removing Orifice Tube
Courtesy of FORD MOTOR CO.

Fig. 16: Removing Broken Orifice Tube
Courtesy of FORD MOTOR CO.

Orifice Tube Kit

1. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Remove liquid line from vehicle. Locate orifice tube in metal portion of liquid line (3 indented notches or circular depression). See Fig. 17 .
2. Note angular positions of liquid line ends for reassembly. Cut a2 1/2" (63.5 mm) section from tube at orifice location. DO NOT cut closer than 1" (25.4 mm) from start of bend in liquid line.
3. Using pliers, carefully remove orifice tube from housing. Clean out liquid line to remove contaminants. Lubricate "O" rings with refrigerant oil. Assemble the orifice tube kit on the liquid line. See Fig. 18 . Ensure replacement orifice tube is same color as one removed.
4. Ensure flow direction arrow points at evaporator. While holding hex of liquid line in a vise, tighten each compression nut to 65-70 ft. lbs. (88-95 N.m). Reconnect line using new "O" ring lubricated with refrigerant oil. Evacuate, recharge and leak test system. Check for proper operation.

Fig. 17: Determining Orifice Tube Location (Ford)
Courtesy of FORD MOTOR CO.

Fig. 18: Installing Orifice Tube Kit (Ford)
Courtesy of FORD MOTOR CO.

REFRIGERANT RECOVERY/RECYCLING

Refrigerant recovery/recycling equipment is used to remove refrigerant from vehicle's A/C system without polluting atmosphere. To remove and recycle refrigerant, ALWAYS follow instructions provided with the refrigerant recovery/recycling equipment being used.

The removed refrigerant is filtered, dried and stored in a tank within the recovery/recycling equipment until it is ready to be pumped back into the vehicle's A/C system.

NOTE:

Separate sets of hoses, gauges and refrigerant recovery/recycling equipment MUST be used for R-12 and R-134a systems. DO NOT mix R-12 and R-134a refrigerants, as their refrigerant oils and desiccants are NOT compatible.

FORD MOTOR CO.

1. Connect Rotunda Recovery/Recycling Equipment (078-00800) hoses to high-side and low-side service valves. See SERVICE VALVE LOCATIONS under SYSTEM SERVICE VALVES .
2. Turn refrigerant recovery/recycling equipment on. Allow unit to run until vacuum is obtained. Once vacuum reading is obtained, close inlet valve (if equipped) on refrigerant recovery/recycling equipment. Shut refrigerant recovery/recycling equipment off.

   NOTE:

   On some applications, refrigerant recovery/recycling system will automatically shut off through the use of a low pressure switch. On other applications, refrigerant recovery/recycling equipment must be manually shut off.

3. Allow system to remain closed for about 2 minutes while observing pressure readings on the refrigerant recovery/recycling equipment.
4. If pressure reading remains at zero, disconnect hoses from service ports. If pressure reading is greater than zero, repeat steps 2) and 3).

FLUSHING A/C SYSTEM

NOTE:

A/C system flushing or filtering should be performed to remove contaminates resulting from a compressor failure.

FORD MOTOR CO.

CAUTION:

Accumulator/receiver drier, muffler, hoses, thermal expansion valve and fixed orifice tube should be removed. DO NOT flush these components because residual flushing agent cannot be completely removed. Except for hoses, these components are generally replaced after A/C system contamination. Hoses can be reused unless they are clogged with debris. Only flush evaporator core and condenser core, and metal inlet and outlet lines.

1. Manufacturer recommends flushing contaminated system using one gallon of Ford A/C System Flushing Solvent (F4AZ-19579-A), a new Motorcraft filter (FL-1A) and a Rotunda A/C System Flusher (014-00991). DO NOT reuse flushing solvent and filter, they are intended to be used only on one vehicle only. Follow manufacturer's operating instructions for use of Rotunda A/C system flusher.
2. If an A/C system flusher is not available to clean A/C system, an in-line filter kit can be used. Two filter kits are available. Filter kits are used with either a rubber lined suction hose or with a nylon lined suction hose located between compressor and evaporator. Rubber lined hose has a wall thickness of 1/4" and nylon lined hose has a wall thickness of 1/8". See Fig. 19 .
3. Each filter kit has 2 filters. A temporary pancake filter and a permanent in-line suction filter. The pancake filter is installed between condenser core and evaporator core orifice. The permanent filter is installed in the suction line between the accumulator and the compressor. See Fig. 20 .
4. If A/C system is contaminated because of compressor failure, discharge system using approved refrigerant recovery/recycling equipment. Install replacement compressor and correct amount of new refrigerant oil. Install replacement accumulator and correct amount of new refrigerant oil.
5. Cut suction hose between compressor and accumulator (closer to compressor). Measure side wall of suction hose. If hose side wall is 1/4", use in-line filter labeled USE WITH RUBBER INNER LINED HOSE. If hose side wall is 1/8", use in-line filter labeled USE WITH NYLON INNER LINED HOSE. Remove a length of suction hose to accommodate suction filter and install filter. On filter for nylon lined hose, install 2 "O" rings on each filter tube. On both filters, use hose clamps provided in filter kit and ensure filter is correctly oriented for refrigerant system flow. See Fig. 19 .
6. Replace fixed orifice tube. If fixed orifice tube is located in the liquid line between condenser and evaporator, replace liquid line. Install pancake filter in liquid line between condenser and evaporator (fixed orifice tube). Ensure filter inlet is toward condenser.
7. Evacuate, charge and leak test A/C system. See the following subjects:
   • EVACUATING A/C SYSTEM
   • CHARGING A/C SYSTEM
   • LEAK TESTING

   Check new filters and hoses for clearance from other engine components. Use tie straps if necessary.

8. Place a fan in front of the radiator. Turn A/C control to ON position, blower motor to maximum speed, and temperature control to full cold position. Start engine and allow to idle. Ensure A/C is operating properly. Slowly bring engine speed up to approximately 1200 RPM. Set engine speed at 1200 RPM and run it for one hour with A/C system operating.
9. Stop engine. Discharge A/C system, using approved refrigerant recovery/recycling equipment. Allow engine to cool, remove pancake filter and discard filter. Reconnect liquid line, evacuate, charge and leak test A/C system. See EVACUATING A/C SYSTEM, CHARGING A/C SYSTEM and LEAK TESTING. Ensure A/C system is operating properly.

Fig. 19: Permanent A/C System Filters (Ford)
Courtesy of FORD MOTOR CO.

Fig. 20: Temporary Pancake Filter (Ford)
Courtesy of FORD MOTOR CO.

EVACUATING A/C SYSTEM

FORD MOTOR CO.

1. Close both valves on manifold gauge set. Connect manifold gauge set to high-side and low-side service valves. See SERVICE VALVE LOCATIONS under SYSTEM SERVICE VALVES . Connect a hose to center connector on manifold gauge set and evacuation pump.
2. Open both valves on manifold gauge set. Operate evacuation pump until low-side vacuum reading is at least 29.5 in. Hg. Continue operating evacuation pump for 30 minutes.
3. Close both valves on manifold gauge set. Turn off evacuation pump. Observe low-side gauge. Any loss of vacuum in 5 minutes indicates a system leak. Perform leak testing procedure, and repair system as necessary. See LEAK TESTING .

CHARGING A/C SYSTEM

FORD MOTOR CO.

1. With manifold gauge set connected, attach refrigerant container to hose on center connector of manifold gauge set. Fully open refrigerant container valve, and purge air from center hose.
2. Disconnect electrical connector from clutch cycling pressure switch located on the accumulator. Install jumper wire between clutch cycling pressure switch connector terminals.
3. Open low-side valve on manifold gauge set, and allow refrigerant to enter system. When refrigerant is no longer being drawn into system, start and operate engine. Place A/C-heater controls on maximum cold position with blower fan on high speed.

   NOTE:

   In areas where ambient air temperature is high, it may be necessary to operate a high output fan to blow air through condenser and radiator.

4. When proper amount of refrigerant has been added, close low-side valve on manifold gauge set. Remove jumper wire, and connect clutch cycling pressure switch. Reinstall electrical connector.
5. Operate system to verify proper operation and normal system pressures. Disconnect manifold gauge set. Install service port caps. Check system for leaks.

LEAK TESTING

TYPES OF LEAK DETECTORS

Bubble Solution Detector

This is a solution applied externally at suspected leak points. Leaking refrigerant will cause the detector to form bubbles and foam. A soap and water solution also works well.

Dye Solution

This is a colored solution that may be introduced into the A/C system. The dye will show up and color components at leak points. Some manufacturers offer refrigerant containing a Red dye. This dye-containing refrigerant is installed by normal charging procedures. Other dye solutions are visible with a Black light only.

Electronic Detector

This instrument will draw in any leaking refrigerant through a test probe, and then sound an alarm or create a flashing light if refrigerant is found. It is the most sensitive of the leak detectors used. See Fig. 21 .

Fig. 21: Electronic Leak Detector

PREPARATION FOR LEAK TESTING

Connect manifold gauge set to air conditioning system. Ensure low-side and high-side gauge set valves are closed. Check system pressure. It should be at least 50 psi (3.5 kg/cm² ). If low, add just enough refrigerant to bring system to 50 psi (3.5 kg/cm² ).

Ensure all joints, connections, and fittings are free of oil dirt and other contaminants. Using a refrigerant leak detector, check all refrigerant line connections for leaks. Check condenser and compressor seal area.

Refrigerants are heavier than air. Always check for leaks at bottom of refrigerant lines and components. Refrigerant oil will leak with refrigerant. Visually check all connections and compressor clutch area for oil stains. If compressor shaft seal is leaking, a fresh oil streak will normally be seen on underside of hood, above compressor clutch.

Always perform leak testing after A/C service. Move refrigerant leak detector slowly to check for leaks, as leaks will not be detected if leak testing is performed too quickly.

BUBBLE DETECTOR LEAK TESTING PROCEDURE

This leak detection method is recommended when it is impossible or difficult to determine the exact location of the leak using other methods. Although commercial bubble detectors are more effective, household soap solutions may be used.

Using the dauber that comes with the commercial soap solution, apply the solution to all joints, connections, fittings or controls where a leak might be suspected. If high-suds household solutions are used, apply them with a small brush. Wherever bubbles form, leaks are present and must be repaired. check the entire system as there may be more than one leak.

ELECTRONIC LEAK TESTING PROCEDURE

NOTE:

Some electronic leak detectors will function on only R-12 systems or on only R-134a systems, and some will function on both R-12 and R-134a systems. Familiarize yourself with the tester being used and know what type of system you are leak testing.

Electronic leak detectors should be used in well ventilated areas. Avoid using them around explosive gases. Always follow manufacturer's instructions for the specific tester being used. If none are available, proceed as follows:

1. Turn all controls and the sensitivity knob to the OFF position or zero setting. Plug the leak detector into an approved source of voltage if not battery operated. Turn the switch ON, and allow the unit to warm up for approximately 5 minutes.
2. Check operation of the tester by positioning the probe in a reference source where refrigerant is known to be present in small amounts. Adjust the controls and sensitivity knob until detector reacts properly. Move probe away from refrigerant source and the reaction should stop. If it continues, adjust the sensitivity knob to a lower setting.
3. When tester reacts properly, leak test air conditioning system by moving probe under all components, fittings and connections. Keep the probe moving. DO NOT hold it in constant contact with refrigerant. When leaks are found, repair them as necessary. Keep in mind that there may be more than one leak.

DYE SOLUTION LEAK TESTING PROCEDURES

CAUTION:

Dye-charged refrigerant cans are available to be used as internal leak detectors. The use of this type of solution may void some manufacturer's warranties. Be sure to check with the A/C system manufacturer concerning the use of dye-charged leak detectors. Dyes which work in R-12 systems will not work in R-134a systems.

The following procedure is for introducing a dye solution, not dye-charged refrigerant, into the air conditioning system.

1. Connect manifold gauge set to air conditioning system in a normal manner. Remove center hose from manifold gauge set, and replace it with a short piece (6" long) of 1/4" tubing using two 1/4" flare nuts. Connect a container of dye solution to the tubing.
2. Connect one end of the gauge set's center hose to the dye solution. Connect a container of refrigerant to the other end of the hose. Operate the engine at idle speed. Set the air conditioning system for maximum cooling. Slowly open the low-side hand valve to allow the dye solution to enter the system.
3. Charge the system to at least 50% capacity. Operate the system for 15 minutes, and then shut off both the air conditioning system and the engine. Check all connections for signs of the colored dye solution. Check the vehicle again 24 hours later. If leaks are found, repair as necessary.

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