Air Conditioner Compressor Not Starting - Causes & Solutions

Figure 1: The repair worker is inspecting the air conditioner.

As is known to us, the refrigeration compressors is the heart of the air conditioner. The compressor, which is generally installed in the outdoor unit, plays the role of compressing refrigerant in the refrigeration cycle. The air conditioner compressor extracts the refrigerant from the low-pressure area and sends it to the high-pressure area after compression for cooling and condensation. The heat is emitted into the air through the radiator, while the refrigerant also changes from a gas state to a liquid state, and the pressure rises.

After the air conditioner is started, the compressor will keep working to achieve control of the temperature. But many users report that the compressor of the air conditioner at home does not operate at all. Do you know the reasons? We will take you to figure it out.

Reasons of Air Conditioner Compressor not Starting

* Insufficient Freon

In general, due to long-term operation with insufficient Freon, the compressor could not start. It’s the improper installation that leads to refrigerant leakage.
Solution: Add Freon.

the worker is adding freon to the central air conditioner

Figure 2: Adding Freon to the air conditioner.

* Remaining Air

When installing, the worker did not discharge the air in the refrigeration system. As a result, there is sometimes ice blockage, thus increasing the compressor load. The increased compressor load makes the temperature of the compressor higher. And the refrigeration oil will deteriorate under a high temperature for a long time and will not play the role of lubrication and cooling, which further increases the temperature of the compressor. The insulation of the coil is reduced due to high temperature, causing damage to the compressor.
Solution: Pay attention to the installation process.

* Power Leads Faults

The power leads faults mean that the power supply is not connected or there is no power. The power lead socket with bad contact, or the small diameter of the power supply wire, or aging wire, or the low power supply voltage, all cause the compressor not to start. It is recommended to install the voltage regulator for home use. In addition, the connecting pipe that is bent and flat would also cause the compressor workload to increase.

Fixed-frequency air conditioner starting voltage: 187V (fluctuation range: 198-242V)
Varied-frequency air conditioner starting voltage: 156V (fluctuation range: 176-264V)

Solution: Check whether the power lead is aging.

* Lock Protection Function

The Lock protection function may lead the compressor to fail to operate and you can refer to the manual to start it. If the compressor works at a high temperature for a long time, it will result in insulation reduction, low coil resistance, and increasing starting current. So the compressor temperature rises instantly.
Solution: Unlock the compressor referring to the manual.

* Electric Wiring Failure

Figure 3: A compressor relay.

Solution
You should disconnect the differential pressure relay and the high voltage circuit breaker. And then you would press the reset button of the differential pressure relay until the pressure changes, and the contact can be closed or the disconnected pressure can be readjusted.

Reasons of Air Conditioner Faults

The battery of the remote control is low. You should replace its battery regularly (once every three months). If the battery is low, it may stop the human-machine dialogue function. The air conditioner can not receive the indoor temperature to form a temperature difference. So it can not be started.

When the air conditioner is turned on for refrigeration or heating for the second time, the compressor will have a protection delay of 3 minutes.

When the air conditioner is for heating, the indoor unit and outdoor unit would be preheating to avoid cold air, so the air conditioner will automatically run the anti-cold air function. Once the heat exchanger temperature reaches a certain value and ensuring that the air conditioner blows the hot air, the ac will start to operate.

The outdoor temperature is low. Under minus 8 ℃, the fixed-frequency air conditioner would be standby for a long time, as well as varied-frequency ac under minus 10 ℃ and DC varied-frequency ac under minus 18 ℃.

This phenomenon may also occur in the morning before sunrise. This phenomenon is due to the low-temperature protection function of the air conditioner, which is to prevent the liquid refrigerant from returning to the compressor to cause a liquid strike and damage the compressor. (and vice versa when it is for cooling)

Extremely low or high voltage.

Other signals (such as “mobile phone or fluorescent lamp") interfere with the communication of the air conditioner. After powering off for 3 minutes, you can turn on it again.

The remote control setting is wrong, such as "cooling" in winter or "heating" in summer.

Why Air Conditioner Failing to Start in Summer

Figure 4: The compressor is stuck.

The compressor is stuck in the cylinder or the starting coil is burnt out.

The compressor’s starting capacity is not enough or burnt out.

Release the refrigerant and increase the capacitance. At the moment of starting it, you should pad its bottom with wood and hammer it. If this does not work, you should replace the compressor.

Replace the compressor capacity.