Heating and Air Conditioning: Service and Repair

REFRIGERANT RECOVERY, EVACUATION AND CHARGING




REFRIGERANT RECOVERY
When discharging refrigerant out of A/C system, always recover it by using refrigerant recovery and recycling equipment. Discharging it into atmosphere would cause adverse effect to environments.

NOTE: When handling recovery and recycling equipment, be sure to follow the instruction manual for the equipment.

EVACUATING SYSTEM
1. Whenever opened (exposed to atmospheric air), air conditioning system must be evacuated by using a vacuum pump. The A/C system should be attached with a manifold gauge set, and should be evacuated for approx. 15 minutes.

NOTE: Do not evacuate before recovering refrigerant in system.

2. Connect high and low charging hoses of manifold gauge set respectively as follows:
High Charging Hose -> Compressor Delivery Hose
Low Charging Hose -> Compressor Suction Hose

3. Attach center charging hose of manifold gauge set to vacuum pump.
4. Operate vacuum pump, and then open suction-side valve (Lo) of manifold gauge set.

If there is no blockage in the system, there will be an indication on high pressure gauge.
When this occurs, open the other-side valve (Hi) of the set.
5. Approx. 10 minutes later, low pressure gauge should show a vacuum lower than 760 mmHg providing no leakage exists.

NOTE:
- If the system does not show a vacuum below 760 mm Hg, close both valves, stop vacuum pump and watch movement of low pressure gauge.
- Increase in the gauge reading suggests existence of leakage. In this case, repair the system before continuing Its evacuation.
- If the gauge shows a stable reading (suggesting no leakage), continue evacuation.

6. Evacuation should be carried out for a total of at least 15 minutes.
7. Continue evacuation until low pressure gauge indicates a vacuum less than 760 mmHg, and then close both valves.
8. Stop vacuum pump. Disconnect center charging hose from pump inlet. Now, the system is ready for charging refrigerant.

CHARGING SYSTEM WITH REFRIGERANT
The air conditioning system contains HFC-134a (R-134a).
Described here is a method to charge the air conditioning system with refrigerant from the refrigerant service container.

When charging refrigerant recovered by using the refrigerant recovery and recycling equipment (when recycling refrigerant), follow the procedure described in the equipment manufacturer's instruction manual.

WARNING:
- Your eyes should not be exposed to refrigerant (liquid).
Any liquid Refrigerant HFC-134a (R-134a) escaping by accident shows a temperature below freezing point. Should liquid HFC-134a (R-134a) get into your eyes, it may cause a serious injury.
To protect your eyes against such accident, it is necessary to always wear goggles. Should it occur that HFC-134a (R-134a) strikes your eye(s), consult a doctor immediately.
a. DO NOT USE YOUR HAND TO RUB THE AFFECTED EYE(S). INSTEAD, use quantities of fresh cold water to splash it over the affected area to gradually raise temperature of such area above freezing point.
b. Obtain proper treatment as soon as possible from a doctor or eye specialist.

- Should the HFC-134a (R-134a) liquid come into contact with your skin, the affected area should be treated in the same manner as when skin is frostbitten or frozen.
- Refrigerant must not be handled near where welding or steam cleaning is performed.
- Refrigerant should be kept at a cold and dark place. It should never be stored where a high temperature is anticipated, e.g. where exposed to direct sun light, close to fire or inside vehicle (including trunk room).
- Avoid breathing fumes produced when HFC-134a (R-134a) is burned. Such fumes may be hazardous to health.

CAUTION:
- ALWAYS CHARGE THROUGH LOW-SIDE of A/C system.
- NEVER CONNECT ON HIGH-SIDE of A/C system.
- Do not charge while compressor is hot.
- When installing tap valve to refrigerant container to make a hole there through, carefully follow directions given by manufacturer.
- A pressure gauge should always be used before and during charging.
- The refrigerant container should be emptied of refrigerant when discarding it.
- The refrigerant container should not be heated up to 40 °C (100 °F) or over.
- Refrigerant container should not be reversed in direction during charging. Reversing in direction causes liquid refrigerant to enter compressor, causing troubles, such as compression of liquid refrigerant and the like.

PROCEDURE OF CHARGING




1. Check to make sure that hoses are routed properly after evacuating the system (see the figure).
2. Connect the manifold gauge set in position. Thus open refrigerant container valve to purge the charging line. Then open the low pressure-side valve.

WARNING: Make sure that high pressure-side valve is closed securely.

3. Start engine and keep engine speed at 1000 r/min. Then, operate air conditioning.
4. Charge A/C system with refrigerant in vapor state. At this time, refrigerant container should be held upright.




5. When refrigerant container is emptied, use following procedure to replace it with a new refrigerant container.
a. Close low pressure valve.
b. Replace empty container with a refrigerant container which has been charged with refrigerant. When using refrigerant container tap valve, use following procedure for replacement.
1. Retract needle and remove refrigerant container tap valve by loosening its plate nut.
2. Install previously-removed refrigerant container tap valve to a new refrigerant container.




c. Purge any air existing in center charging hose. When using refrigerant container tap valve, use following procedure to purge air.
1. Once fully tighten refrigerant container tap valve and then loosen (open) plate nut slightly.
2. Open low pressure valve of manifold gauge set a little.
3. As soon as refrigerant comes out with a "hiss" through a clearance between refrigerant container and tap valve, tighten plate nut as well as manifold gauge set low pressure valve.
4. Turn handle of tap valve clockwise so that its needle is screwed into the new container to make a hole for refrigerant flow.




6. After the system has been charged with specified amount (600 g, 21.0 oz) of refrigerant or when low and high pressure gauges have indicated specified value below respectively, close low pressure side valve of manifold gauge set. At this time, look into the sight glass of receiver/dryer and check that there are no bubbles in it, which means that the system is fully charged.

Low pressure gauge when charged with specified amount About 245 kPa (2.5 kg/sq.cm, 35.5 psi)

High pressure gauge when charged with specified amount About 1,470 kPa (15 kg/sq.cm, 213 psi)

REMOVING MANIFOLD GAUGE SET
When A/C system has been charged with a specified amount of refrigerant, remove manifold gauge set as follows:
1. Close low pressure-side valve of manifold gauge set. (The high pressure-side valve is closed continuously during the process of charging.)
2. Close refrigerant container valve.
3. Stop engine.
4. Using shop rag, remove charging hoses from service valves. This operation must be performed rapidly.

WARNING: High pressure-side is naturally under high pressure. So, care must be used to protect your eyes and skin.

5. Put caps on service valves.




LEAK-TESTING REFRIGERANT SYSTEM
Whenever a refrigerant leak is suspected in the system or any service operation has been performed which may result in disturbing lines or connections, it is advisable to test for leaks. Common sense should be used in performing any refrigerant leak test, since the need and extent of any such test will, in general, depend upon the nature of a complaint and the type of a service performed on the system.

LIQUID LEAK DETECTORS:
There are a number of fittings and places throughout the air conditioning system where a liquid leak detector solution may be used to pinpoint refrigerant leaks.

By merely applying the solution to the area in question with a swab, such as attached to the cap of a via, bubbles will form within seconds if there is a leak.

For confined areas, such as sections of the evaporator and condenser, an electronic (gas) leak detector is more practical for determining leaks.