See Figure 1
Before servicing the air conditioning system read and adhere to all of the following warnings:
Obstructed air passages, broken belts, disconnected or broken wires, loose clutch, loose or broken mounting brackets and many refrigerant leaks may be determined by visual inspection of the parts.Checking for Oil Leaks
Refrigerant leaks show up as oily areas on the various components because the compressor oil is transported around the entire system along with the refrigerant. Look for oil spots on all the hoses and lines, and especially on the hose and tubing connections. If there are oily deposits, the system may have a leak, and you should have it checked by a qualified repairman.
Most common leaks are caused by damaged or missing O-ring seals at the various hose and component connections. When these O-rings are replaced, the new O-rings should be lubricated with refrigerant oil and care should be taken to keep lint from shop towels or rags from contaminating the internal surfaces of the connection. Leakage may occur at a spring lock coupling if the wrong O-rings are used at the coupling.
Another type of leak may appear at the internal Schrader-type A/C charging valve core in the service gauge port valve fittings. Have the system checked by a professional A/C mechanic if this is expected.
A small area of oil on the front of the compressor is normal and no cause for alarm.Checking the Compressor Belt
Refer to drive belt procedures in this section for more information about belt adjustment procedures.
Inspect the belt carefully for glazing on the V surfaces, which indicates slippage (there should be a slight crosshatch or fabric appearance), cracks (which usually start at the center) or any other damage, including being too stretched to permit a tight adjustment. Replace the A/C belt if there is any sign at all of damage, as this belt carries a great deal of load.
On most air conditioning installations, the compressor is mounted directly to the block or cylinder head and remains in the same position regardless of the belt adjustment. An idler bracket is locked in place by two locknuts and a pivot bolt. It is rotated via a nut that is welded onto its front surface to adjust the compressor drive belt.
Check the belt tension by depressing the belt in the center of its longest span with your thumb. It should depress approximately 5 / 16 in. (11mm). If the tension is incorrect, loosen the two lockbolts and the pivot bolt. Then, turn the bracket via the weld nut until tension is correct. Hold the bracket in position as you first tighten the locking bolts and then tighten the pivot bolt. Recheck the tension to make sure it has not changed. Readjust if necessary.
CHECKING REFRIGERANT LEVEL
See Figure 2
The first order of business when checking the sight glass is to find it. It will be in the head of the receiver/drier. In some cases, it may be covered by a small rubber plug designed to keep it clean (some vehicles may not have a sight glass). Once you've found it, remove the cover, if necessary, wipe it clean and proceed as follows:
- With the engine and the air conditioning system running, look for the flow of refrigerant through the sight glass. If the air conditioner is working properly, you'll be able to see a continuous flow of clear refrigerant through the sight glass, with perhaps an occasional bubble at very high outside temperatures.
- Cycle the air conditioner ON and OFF to make sure what you are seeing is a pure stream of liquid refrigerant. Since the refrigerant is clear, it is possible to mistake a completely discharged system for one that is fully charged. Turn the system OFF and watch the sight glass. If there is refrigerant in the system, you'll see bubbles during the OFF cycle. Also, the lines going into and out of the compressor will be at radically different temperatures (be careful about touching the line going forward to the condenser, which is in front of the radiator, as it will be very hot). If the bubbles disappear just after you start the compressor, there are no bubbles when the system is running, and the air flow from the unit in the car is cold, everything is OK.
- If you observe bubbles in the sight glass while the system is operating, the system may be low on refrigerant. It is also possible, when the work area temperature is above 110°F (43°C) or below 70°F (21°C), occasional foam or bubbles will be present; these bubbles are normal. However, you may still want to have it checked by a professional.
- If all you can see in the sight glass is oil streaks, this is an indication of trouble. This is true because there is no liquid refrigerant in the system (otherwise, the oil would mix with the refrigerant and would be invisible). Most of the time, if you see oil in the sight glass, it will appear as a series of streaks, although occasionally it may be a solid stream of oil. In either case, it means that part of the charge of refrigerant has been lost.
The refrigerant system will not be low on refrigerant unless there is a leak. Have the system checked for a leak by a qualified mechanic.
CHARGING & DISCHARGING
Fluorocarbon refrigerants like that used in car air conditioners damage the upper atmosphere, destroying its ability to screen off dangerous solar radiation. For this reason, air conditioning service shops are required to use special charging/evacuating stations to condense and recover refrigerants rather than releasing them to the atmosphere. Since these environmental regulations also apply to the do-it-yourselfer, you should have your system discharged by a professional. Having a qualified and trained mechanic discharge, evacuate and recharge your A/C system prevents harmful personal accidents, damage to the environment, and legal repercussions from ruining your day.