Ac problem

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1. Make sure what is the required amount of gas. From factory, all systems

have a decal under the hood that give the data. If the decal is missing or you

are not sure, please specify make, model, and the type of refrigerant used and

to know if your system has oil. Oil starvation is the main reason of compressor

failure. Oil can be added to the system in two ways: with oil injectors or through

the low side port under vacuum. The procedure to add oil through vacuum is

2. Connect both blue and red gauge hoses to the system's service ports. The

discharge port (red hose) is located somewhere between the compressor and

expansion device, either before the condenser or after it. In R134a systems, the

port is the thicker of both, while in R12 systems is the thinner one. In some

aftermarket systems, the port is located in the back of the compressor. If your

ports are located in the compressor, the low side is marked by an "S" and the

high side by an "H". Port caps have an "L" for low or "H" for high.

3. Open both gauge valves. Connect the common hose (yellow one) to the

vacuum pump. Make sure both gauge needles are zeroed down. Needle is

adjusted by turning a fine screw inside the dial. You must remove the plastic

lens to do this.

4. Turn the pump on. You'll notice that both gauge readings begin to drop. The

blue gauge's needle will even dip into negative values. The desired low side

reading should be less than -25, while the high side will remain at 0.

5. After approximately 5 minutes, close both gauge valves. Turn the pump off,

and observe the needles. Any movement will indicate vacuum loss. The faster

the movement, the greater the loss. If after two minutes you don't see any

needle movement, open both valves, turn the pump on, and continue vacuum

for not less than 30 minutes. Close both valves then turn the pump off.

6. Get ready to charge. Have the necessary refrigerant amount handy. Cans

make charging easier and more precise unless you have a charging cylinder or

a precision scale.

7. Disconnect the yellow hose from the vacuum pump and connect it to the can

tap or charging cylinder valve. You can charge in two ways: liquid (can upside

down) or gas. Liquid charging is a lot faster but not recommended unless you

extreme care or have experience. Traditional (gas) charging is slower but safer.

8. Once you've decided, and with the can or container connected, unscrew the

top yellow hose connection (at the gauges) allowing refrigerant to escape for a

couple of seconds. This will purge the air out of the hoses so you make sure

that all you dispense is refrigerant. You can do this venting in liquid form so you

can see when a fine, steady stream of refrigerant escapes indicating that all the

9. "Flood" the system with liquid refrigerant (can upside down) by opening the

red valve (high side) until it won't take anymore. Close the red valve. Jump the

low pressure cycling switch (if so equipped). If you don't know what this is or

10. Turn the engine on. Turn the A/C into MAX on its third or higher blower

speed. You'll note that both gauge readings are now positive. The red gauge

should read between 100 and 150, while the blue gauge between 5 and 15. If

you are charging with cans, don't forget to purge air out the hose after hooking

don't have to), you'll notice the compressor cycling frequently on and off. That is

normal. The cycling will disappear as you dispense more refrigerant. The only

disadvantage of frequent compressor cycling is that charge will take longer.

Needles will move up and down with every cycle. This is normal. Do not jump

any switch unless you are absolutely certain!.

WARNING: DANGER

NEVER OPEN THE RED VALVE WHILE CHARGING. The red valve is to be

opened only during pre-charge, vacuum, or when a system is evacuated. Its

function is keeping an eye on the high side only. It must be closed at all times. If

you have any doubts, wait until you receive information. Severe injury or death

may occur. Remember: ALWAYS wear safety goggles. NEVER charge your

system in a closed environment.

There are two ways to charge: gas (can or cylinder up), or liquid (can or cylinder

upside down). A compressor is designed to compress gas. Direct liquid charge

will harm the compressor if suction pressure is not controlled. Liquid charging is

supervision. Liquid charging can be done if the suction port is away from the

compressor (some compressors have the suction valve in its body).

Liquid charging can be done never exceeding a 50 PSI suction pressure. If you

can't control it, charge in gas form. In cooler weather, cans may freeze. You

may immerse them in water and shake them while charging.

11. Once about 2/3 of the charge has been dispensed into the system, spray

water in the condenser to optimize heat exchange and speed the process.

When you get the condenser wet, vent temperature is likely to raise. This is

normal. You'll also note pressure drop in both gauges.

12. Once the specified amount has been dispensed, close the blue valve. Let

the system run for a minute. Turn the A/C off and then the engine. Wait another

minute and disconnect the couplers from the service ports. Disconnect the low

side first. If you jumpered a switch, reconnect it too.

Optimum cooling performance is attained after 10 minutes of operation. Our

own acceptance criteria is at least 50°F in the center vent to the driver side at

idle after 10 minutes or less. Remember: cooling increases while the vehicle is

in motion.