How to test car ac compressor with multimeter
AC stands for Air Conditioning, and often most people overlook it, causing it to stop working altogether. If you notice your air conditioner compressor blowing hot air on a hot day, you probably have a faulty component. Therefore, if your air conditioning compressor is faulty, you may have engine damage because it will stall and your car will suddenly stop while driving.
As a result, this can lead to an accident and injury to you and other passengers. In addition, damage to the air conditioning compressor often leads to problems in the steering system as its performance is reduced, and the brakes are also prone to failure.
Therefore, it is clear that the air conditioning compressor plays a crucial role in the production of cold air and, consequently, in its circulation through the air conditioning unit. If your vehicle’s air conditioning system is not working effectively, you most likely have a problem that can affect your overall driving experience.
Conclusion:
Fortunately, a faulty air conditioning compressor can be repaired. All you need to do is run a series of tests to examine it with a multimeter and find out exactly where the problem may be. Once you have identified the problem, schedule an appointment with an AX compressor expert or mechanic to have the problem fixed correctly.
How to check the A/C compressor with a multimeter.
Step 1: Check if the air conditioner compressor is damaged.
Before testing the A/C compressor, make sure the A/C circuit is completely off. This is important and will prevent electrical shock when testing the compressor. Therefore, make it a habit to turn off the air conditioner compressor circuit and any other switches around it.
Next, remove the front panels by unscrewing them from the air conditioner. This will give you access to the interior, especially the vents and many other internal components. Once this is done, you should now remove the power access panel to see how the wires connect to the AC compressor unit. Also check for burned terminals or even inside the system.
Step 2: Check the power and ground at the AC compressor connector.
Make sure that the compressor power terminals are disconnected from the coupling and that the multimeter is set to direct current (DC). At one of the terminals, connect the positive probe leads to the clutch power terminal, then connect the negative probe leads to battery ground, set the AC and then start the engine.
Observe the voltage on the multimeter; if it is zero, route the positive probe lead to another terminal on the power connector. If the displayed reading is still zero this time, route the negative probe lead to another terminal.
If both probe wires are connected to the power terminals, this is confirmation that both the ground and the compressor clutch are receiving sufficient current; therefore, the clutch coil is a defective component that should be replaced. Some clutches are usually repairable, while others often require replacement.
Step 3: Find out why your compressor clutch is not receiving power
Connect the negative battery terminal to a multimeter and check for voltage at terminals 2 and 3. If the multimeter shows no voltage, check the relay wiring and fuses.
If there is power, apply the positive test lead to terminal four and the negative to terminal three and you will see a battery voltage reading on the multimeter. If you don’t see any reading, assume the PCM has a problem and cannot generate ground for the control relay coil.
Step 4: Do not test the relay coil ground.
If there is little or no refrigerant pressure in the system because the condenser is clogged or the TMX valve and orifice are damaged, consider that the PCM is not generating ground to the compressor relay coil. So try to find the maximum and minimum pressure switch, and then connect the negative and positive sensor wires to the appropriate terminals.
Next, start the vehicle’s engine and turn the air conditioner on full blast while checking the voltage on the multimeter at one of the terminals. If voltage is present, it means that the PCM is generating current and therefore you should perform an identical test on switch 5. If voltage is present on all switches, perform a continuity test on all switches.
Step 5 – Check the continuity of the pressure switches.
Set the multimeter to ohmic, then connect one lead of the meter to the specified terminal (5) located on the low pressure switch and the other lead to terminal (7) of the pressure switch. When the switch is closed, it means that the refrigerant is sufficient and has a reading on the display, but if the pressure is too low. The switch will open and you will most likely get an inaccurate reading between terminals 5 and 7.
Perform the same procedure on the maximum pressure switch with the multimeter set to ohms. Connect one of the multimeter test leads to terminal 8 and the other to terminal 6 of the maximum pressure switch.
When the switch is closed, assume that the refrigerant pressure is ideal, as shown by the multimeter reading. If the pressure is too high, the switch will open and the reading displayed will be an infinity between 5 and 7. This means you have a serious problem with the A/C compressor that needs to be fixed by an expert.
Conclusion:
After reviewing the above information, you should already know how to check your AC compressor with a multimeter. It is usually the only basic tool you will need during this test, which shows its overall importance. After performing the test, you will be in a better position to assess whether the AC compressor needs to be replaced or repaired.