How to Check Your Car's Air Conditioning System

How to Check Your Car's Air Conditioning System

Check your vehicle's A/C system prior to when the hot weather arrives to ensure that it's functioning properly and is blowing cold air.

1. While the engine is running does the compressor's clutch work when the air conditioner is turned on? If not, this typically is a sign of an empty (or empty) refrigerant level or an electrical issue. Also, be aware of fast clicking or cycling sounds in the compressor when the AC is turned on. If this happens it could be a sign of an issue with refrigerant levels or other issue. Check it out with your technician. (Note Certain A/C systems block clutches on compressors from engaging at low temperatures, usually under or below forty F.)

2. Are the A/C units blowing cold air? Luke's warm or even air which isn't cooling in any way, could be a sign of an insufficient refrigerant charge within the system of air conditioning. Pressure gauges are a good way to test the refrigerant's charge. If it is low, add refrigerant in order to bring the system fully charged.

3. If the engine is running with the A/C turned off, listen for sounds of knocking or rumbling near the compressor. They could be a sign of a failed clutch on the compressor or the mounting hardware is loose.

4. Are the bolts for mounting A/C components fixed and securely fastened? Are there no loose bolts or loose parts rattling around?

5. Are there caps on the A/C system's ports for service? They keep dirt out and seals to the refrigerant.

6. Examine all belts for wear, cracks, and glass. Get them replaced immediately if you see any of these problems. Also, look for belts that are vibrating when your engine runs and when the air conditioner is turned on. This could be a sign of an untightened belt be tightened, or a malfunctioning auto belt tensioner.

7. Check all cooling and A/C system hoses for cuts scratches, weak spots and indications of leakage. Leakage in hoses of the A/C system is typically spotted through the accumulation of oil and dirt especially around the fittings and connections.

8. Check that the condenser (in the front of your radiator) is free of obstructions like insects or leaves. This can reduce airflow, resulting in lower performance for the A/C. It is possible to wash the condenser to clean it by using an outdoor hose.

Auto Air Conditioner Blowing Warm Air, Not Cooling

Are your car's AC units just blowing warm air and not cooling air? The cooling issue in your car could be the result of any of these

Your AC system could be unable to use refrigerant. This is most likely the most frequent cause of the problem of no cooling. Another reason for no cooling could be the fact that your compressor not operating when you turn on the AC. This could be caused by an electrical problem in the circuit of the compressor or in the magnetic clutch that is driving the compressor. Another reason may be an obstruction within the refrigerant circuit which prevents refrigerant from circulating through the A/C. Another possible cause could be an air blend door within the HVAC unit that is stuck in HEAT position, which is blocking air from moving through the evaporator for the A/C.

Compressor Checks

Start by checking the compressor. Does it turn on when you switch off the air conditioner?

If yes you can tell that the compressor is functioning and the air conditioning system may contain enough refrigerant to create cold air, and the issue is within your HVAC unit. Replace the motor that regulates the door to blend air (this is an extremely difficult task and should be done by a professional as it requires the dismantling of an HVAC system -- roughly 8 to 10 hours! ).

If the compressor fails to activate when you turn on the A/C, you can check whether it is running by juggling the compressor's cable directly into the battery (use the fused jumper wire). If the compressor operates after you jump it and the A/C is blowing cold air, it is because the system has refrigerant. The problem is likely to be a problem with the A/C compressor clutch relay , or an improper clutch switching device and pressure switch.

If the compressor fails to respond when you push it, the issue is an issue with the clutch of your compressor.

If the clutch is engaged but the compressor is unable to rotate (the belt will begin to slide and squeal) The compressor is locked, and you'll need to replace the compressor.

If the clutch on the compressor is engaged and the compressor starts to turn however the A/C isn't blowing cold air, it is likely to be in need of refrigerant, and will require replenishment.

Refrigerant Checks

Attach an AC pressure gauge through the HIGH SIDE port for service (located within the high-pressure hose that connects the compressor and condenser located in on the side of the compartment for the engine). The gauge will let you know whether there is pressure inside the system. By simply pressing the fitting valve of the service fitting using a small screwdriver, to check if refrigerant leaks out is not an accurate test since it informs you of the amount of pressure is present in the system. It could still be a bit of pressure, but not enough to activate the safety switch for low pressure and the compressor won't be activated.

If your air conditioner is running low or depleted of refrigerant. Check for leaks and then ensure that the A/C system is cleared to eliminate air. After air has gone out it can be recharged by using the amount specified in the refrigerant. It is crucial to eliminate all air out since this can affect the cooling efficiency and could cause the compressor to become noisy.

A/C System Functional Checks

When the circuit for refrigeration appears to be functioning (refrigerant within the device, the compressor operating and pressure in the building) however there is not cooling in the system, then the cause could be due to an obstruction in the tube for orifice (located in the high-pressure pipe between the condenser at to the rear of the radiator and the evaporator within the compartment for passengers). An obstruction here can stop the refrigerant from getting into the evaporator and recirculating throughout it. The refrigeration circuit.

When the tube for the outlet has been plugged in, the high-side pressure reading is lower than usual and the low-side reading will be also lower than normal because there is no refrigerant circulated throughout the entire system.

If the refrigeration circuit appears to be operating in a normal manner (compressor running either frost or condensation on the high-pressure line that connects the condenser unit to the evaporator) and there is no cool air blowing through the ducts in the vehicle (and the blower is functioning) The problem is most likely to be due to a BLEND Air door that's locked in its HEAT state or perhaps a severely blocked cabin air filter that is limiting the flow of air. Another possible cause is an issue with the auto thermostat, like an interior thermostat or control unit.

If you are not knowledgeable about A/C repair is to locate repair shops that specialize in repairs to A/C systems and let them identify and fix the problem with your cooling system. The modern A/C systems that incorporate automated climate control are extremely complicated and require specialized tools and expertise to identify and fix.

Troubleshoot Air Conditioning


The most likely reason for an auto air conditioner cooling issue is that there isn't any refrigerant in your system. If refrigerant escapes beyond a leaky compressor O-ring seal, escaped through a pinhole in the condenser or evaporator or leaked out of leaky hoses or hose, the leak must be discovered and fixed before that the unit is recharged.

In many systems, the compressor will not switch on when the refrigerant level is low due to it is the "low-pressure security switch" stops the clutch of the compressor from activating if the pressure in the system is low. This helps protect the compressor from harm caused by the absence of the lubrication.

The first thing to be checking is the engagement of the compressor. If the compressor's magnetic clutch isn't engaged when the air conditioner is on, it could be due to a blown fuse or wiring issue. If the fuse has been blown and replaced, it can restore cooling for a short period of time. However, the root cause of the fuse blowing in the first instance is to be discovered and fixed to stop repeating the same issue again.

In the event that the magnet clutch receives voltage, but isn't engaging the compressor, it is likely that the clutch is in a bad state and has replacing. If there is indication of leakage within the seal of the compressor shaft it is recommended that the seal be replaced.

If the clutch is working but isn't turning on the compressor (the belt might squeak in protest! ) it means that the compressor is jammed and requires replacing.

The majority of compressor failures are caused by a lack of lubrication. This in it's own way could be caused by an insufficient refrigerant supply to the system, blockages (such as a blocked orifice tube that prevents refrigerant or oil from moving through the compressor) or loss of lubricant because of leaks or insufficient procedure for servicing (not adding oil into the system in order to help replace the oil lost by leakage or the replacement of a component) or the use of the incorrect kind of fluid.

R-12 systems require mineral oils R-134a systems use different types of PAG oil as well as POE oil. Utilizing mineral oil in the newer R-134a systems could result in serious problems with lubrication or even the incorrect quality (viscosity) of the PAG oil. Follow the manufacturer's recommendations for your vehicle. the manufacturer's recommendations for compressor oil.

The second thing you must be looking for while tackling the issue of no-cooling is system pressure. In order to do this, you'll need an A/C set of gauges. Connect your gauges to the low and high service fittings. If both of the low and high side gauges show low, your system is insufficient and needs recharge. Before any refrigerant is added, look for leaks in order to determine where the refrigerant is headed.