Precautions
To safely discharge the air conditioning system, use pressure gauges:
1. With the engine off, connect the pressure gauges to the manifold.
2. Connect the red blower hose (high pressure side) collector pressure gauge with a service valve on the high pressure line. It is located on the line going from the compressor to the condenser. Connect blue blower hose (low pressure side) to the suction line. This is a line that runs from the evaporator in the car to the compressor. It is usually large in diameter due to the insulation surrounding it. The valves used in the pipelines are called Schrader valves.
-> Take extreme care when removing the test hoses from the riveted shredder, as some coolant will leak out at high pressure.
3. Place the free end of the center hose in a suitable container or wrap the end in a towel.
4. Slowly open the high pressure manual valve to adjust the refrigerant flow.
If you can't handle the escaping refrigerant, the force of pressure will drag some of the coolant oil with it. This is not desirable and may damage the compressor.
5. Make sure no oil has leaked into the container. If there is oil, slightly close the manual valve.
6. After the manifold pressure gauge reads less than 350 kPa, slowly open the low pressure valve.
7. After depressurizing the system, gradually open the high and low pressure valves until both gauges indicate 0 kPa.
Draining and charging the system
This procedure requires a vacuum pump.
There are no procedures that would partially discharge the system from the refrigerant. Since you have no idea how much coolant is in the system, you cannot know how much to add. To avoid severe damage to the compressor from overcharging, always empty the system completely and evacuate it.
1. Connect manifold pressure gauges.
2. Connect the central hose to the vacuum pump inlet.
3. Turn on the vacuum pump and then open both manual valves.
4. Let the vacuum pump run for approximately 15 minutes. Check that the low pressure gauge reading is greater than 700 mmHg.
If the reading is less than 700 mmHg, close both valves and turn off the vacuum pump. Inspect the system for leaks and repair if necessary.
6. Close manifold gauge valves and shut off vacuum pump.
After draining the system, always check for leaks.
7. Install the refrigerant container valve on the refrigerant can.
8. Connect the central hose to the valve port.
9. Turn the knob clockwise to make holes in the jar for dripping.
10. Turn the knob fully counterclockwise to fill the center hose with refrigerant. Do not open the high and low pressure valves.
11. Loosen the center hose nut connected to the center manifold gauge fitting until a hiss is heard. This will allow a small amount of coolant to bleed the air out of the hose. Wait a few seconds for air to escape from the hose and then tighten the nut.
12. Hang or stand the jar so that it remains upright for the remainder of the procedure. DO NOT turn or tilt the jar while charging.
13. Open the low pressure valve; make sure the high pressure valve is securely closed.
CAUTION: Never attempt to charge the system from the high pressure side.
14. Open the front doors of the vehicle, start the engine and set the blower fan to maximum speed with the air conditioning system on. The engine should run at 1000 rpm. Start filling the system. Use a spring grid to measure the amount of refrigerant in the system. DO NOT exceed the stated weight; more doesn't mean better. Use the following amount of refrigerant when charging.
- 1984-88 Accord: 650-750
- 1989 Accord: 800-900
- 1990-91 Accord: 900-950
- 1984-87 Prelude: 750-850
- 1988 Prelude: 900-1000
- 1989 Prelude: 850-950
- 1990-91 Prelude: 900-950
15. If necessary, change the can to fill the system with refrigerant, but do not forget to close the control valve before changing the can.
16. When the system is completely filled, close the control valve. Keep the engine running for an additional 30 seconds to clear the line and gauges.
17. With the engine running, disconnect the low pressure hose from the union. Disconnect the high pressure side; hold the fitting down and unscrew it quickly to avoid loss of refrigerant.
CAUTION: Always remove pressure gauge hoses from service channel side only! Otherwise, unexpected refrigerant leakage may occur.
18. Replace dust caps at line joints and shut off engine.