Your AC blows cold on driver side hot on passenger side because the vehicle’s AC system is probably malfunctioning. One of the causes of the temperature difference is low refrigerant level.
In this complete article, we’ll explain why your car’s AC is malfunctioning and how to fix it, so let’s get started!
Contents
Why Is Your AC Blowing Cold on Driver Side and Hot on Other Side?
Your AC is blowing cold air on the driver’s side and hot air on the other side because of low refrigerant levels in the AC system, a clogged evaporator or condenser, or a faulty blend door actuator. Other causes include a faulty electrical system and a clogged heater core.
Take note that not every car has an air-conditioning system. Some older car models don’t have one; instead, they use a simple ventilation system that cools the cabin. In contrast, modern and higher-end vehicles have a complete AC system to cool the interior. It is also important to let your mechanic know about these details of your vehicle.
– Faults With the Electrical System
A car’s AC electrical system comprises different components, ranging from wires and fuses to pressure switches. These components work together for the efficient operation of the air-conditioning system. Hence, if one or a couple of those components becomes defective, the air conditioner will malfunction.
Damaged fuses and pressure switches can cause hot air to flow from the AC to the passenger side while colder air blows to the driver’s side. This malfunction can also be a result of frayed wires. Once the wires become worn out, the electrical system can shut down and the car’s AC system won’t function properly.
– Low Refrigerant Level in the AC System
The refrigerant in an air-conditioning system switches between liquid and gaseous states and works with the compressor and evaporator to blow cold air inside the vehicle. It absorbs the heat and humidity within your vehicle to produce cool, dry air. The compressor and condenser are responsible for helping the refrigerant maintain a high-pressure state for blowing cold air.
If the vehicle’s AC has insufficient refrigerant, the compressor won’t be able to raise the system pressure high enough for the expansion valve to successfully cool down the refrigerant. If the refrigerant is not properly cooled, very warm air blowing on one side of the vehicle will malfunction.
The low refrigerant level can be due to leakage. The high pressures of the AC system and the volatile nature of the R-134a refrigerant can cause some of the refrigerant to leak over time. In that case, there will be a temperature difference inside the vehicle.
– Blocked Evaporator or Condenser
Two components require air to pass through a vehicle’s air-conditioning system. The components are an evaporator and a condenser. If any of these components is blocked by debris and dirt, it won’t get the airflow needed for proper operation. Inspect the front of your car and the cabin air filter for dirt and debris because they can affect the operation of a condenser or evaporator.
A clogged condenser and evaporator can cause very warm air to blow on the passenger side while the driver receives cool air. Also, if you notice unusual high pressure before any of the components and unexpected low pressure after them, this is a sign that they might be clogged by dirt, dust, or debris.
– Defective Blend Door Actuator
Every vehicle has a blend door actuator. Blend door actuators are small electric motors that run forward and reverse motion to move the blend door (air mix door) between fresh air and recirculation modes. It is also responsible for moving the air mix door between hot and cold airflow and floor or defrost modes. Thus, it is essential to a car’s AC and heating systems.
If the vehicle’s blend actuator becomes damaged, you will experience inconsistent airflow when using the air conditioner. A stuck actuator can cause hot air to flow toward the passenger side of the vehicle. The malfunction of the actuator means that the desired cold air is diverted incorrectly, leading to an inconsistent temperature in the air-conditioning system. If the gears of the actuator motor become worn out, it will fail to properly regulate airflow inside the vehicle.
– Faults With the Lubrication Levels in the Compressor
Although the refrigerant is the working fluid in a car’s AC, lubrication is vital to the system’s proper functioning. Lubricant is required to smooth the moving mechanical parts of the AC’s compressor. The lubrication oil is used to reduce friction, thereby minimizing mechanical wear during the operation of the compressor. The lubricant also maintains a seal between the high and low sides of the compressor.
If the lubrication level is low, the compressor valves, mating scrolls, vanes, and screws will not properly seal. When this happens, high-side refrigerant pressures will enter the low side of the air-conditioning system. Thus, hot air will be blown inside the vehicle.
Also, if the oil becomes diluted, it will lose many of its lubrication properties and won’t function well with the compressor, causing the passenger side to receive blowing hot air.
– Clogged Heater Core
The heater core is the component that heats the cabin and demists and defrosts the vehicle’s windscreen. It is often described as a small radiator that works with the vehicle’s cooling system. It transfers heat from the engine’s hot coolant to produce cooler air in the interior. The device is inside the HVAC loop after the evaporator and uses the engine cooling liquid to increase temperature.
If there is a clog in the cooling system or heater core itself, it will become inoperative. Blockage in the heater core will cause it to malfunction, and the car’s interior won’t properly receive warmer air. One side of the vehicle will be cool, while the other will receive hot air. A damaged heater core can also cause the build-up of slimy film on the car’s windows.
– Damaged Blower Motor
The blower motor is used to move air through the vehicle’s assembly. This component comprises a motor and blower assembly housed in a metal casing. It is also known as a car heater fan or car heater blower and can be found underneath the dash or behind the glove compartment. The blower motor works with other components to regulate cabin air temperature and ensure the driver and passenger comfortably travel.
However, if the blower motor develops a fault, it will stop functioning correctly. A damaged blower motor will begin to slow down while working, leading to weak airflow and poor climate control inside the cabin. The reduced speed of the blower motor may cause various airflow — which means one side receiving warmer air than the other — in the interior of the vehicle.
What Are the Remedies for an AC Blowing Hot and Cold Air?
The remedies for an AC blowing hot and cold air are unclogging the condenser, replacing the blend door actuator, checking lubrication levels, and replacing the blower motor. Other ways to fix a faulty AC include repairing faults in the electrical system and unclogging the heater core.
If you decide to go to the mechanic, take note that the cost of fixing your car’s AC system depends on the faulty component and the degree of damage to the component. Also, the labor cost for repairing a car AC varies for different cities. You should prepare to spend between $100 and $300 to fix your AC.
– Unblock the Condenser
A clogged condenser will prevent the car AC from working properly, so the blockage should be removed immediately. Turn off the air-conditioning system, locate the condensate drain pipe, and remove the cap from the pipe. You don’t need any tool to remove the pipe. You can do it easily by pulling with your hands. Check inside the drain for debris and dirt that might have blocked the drain line.
After inspecting the drain, remove any visible residue by using your hands. However, be careful not to push it further down accidentally. The next step is to pour distilled white vinegar inside the pipe and close the drain with its cap. Then wait at least 30 minutes before switching on the car AC system again.
– Replace the Blend Door Actuator
A defective blend door actuator cannot be repaired. It has to be replaced. To replace it, use an 8mm socket to remove the screws in front of the heater box and a small flat-blade screwdriver to replace the faulty actuator. As a precaution, you must disconnect the negative battery cable from the vehicle in case of an electrical surge while replacing it.
Depending on the vehicle’s make and model, the blend door actuator can be found in different locations in a vehicle. So, you seeking professional help to replace the faulty actuator is a good approach. Once you notice the signs that show the actuator is defective, you should take the vehicle to an auto repair shop to install a new one. This helps to prevent more damage to the vehicle’s other components.
– Inspect the Lubrication Levels
Due to the importance of lubricant oil in an AC compressor, you must regularly check the lubrication level. Inspect to see if it has the correct amount of oil. If the lubrication level is low, the compressor will malfunction. In contrast, too much oil can coat the evaporator and condenser coils’ inner walls, which reduces their ability to absorb or dissipate heat.
To inspect the lubrication levels, first look at the tag on the AC compressor because it will inform you how much oil the system needs. If you can’t find info on the compressor, another method is to drain the old compressor oil and measure the amount of oil that flows out. Don’t forget to use the correct type of oil that is best suited for the car’s AC system.
– Replace the Blower Motor
A damaged blower motor should be replaced with a new one. Replacing the motor starts with disconnecting the car battery and removing some trim and small panels from the passenger footwell. Sometimes, you may have to remove the glove box, too. The blower motor is usually located behind the dash of the passenger footwell, so it can be accessed and removed by loosening the bolts that secure it.
Once the bolts have been undone, the HVAC connections should be detached alongside the electrical power connector. Then the process is reversed to install the new blower. You should only attempt this if you’re an expert. If you aren’t, you should get an auto mechanic to complete the replacement.
– Repair Faults in the Electrical System
Inspect the electrical system of the AC system to check for damaged or frayed wires. Once you spot them, repair the damaged wires. Sometimes, you may have to replace the defective wires with new cables.
If you don’t have the expertise to perform this operation, it is best if you drive the vehicle down to the shop of a local mechanic or auto-electrician. Professional mechanics are in a better position to diagnose and fix problems with the electrical system of the car’s air conditioner.
– Recharge the AC System
Since insufficient refrigerant can cause the AC system to be undercharged, ensure that the AC has enough refrigerant to function correctly. Inspect the system for leaks and ensure that the leaks are properly sealed.
You can achieve this by pouring Red Angel A/C Stop Leak into the air-conditioning system. Once you’ve sealed the leaks, it is time to recharge the system by adding new refrigerant.
– Unclog the Heater Core
A clogged heater core should be freed of its blockage so that it will effectively produce cool air inside the vehicle. The first step to unclog the core is to locate the heater core hoses, typically at the firewall. Then disconnect the hoses using pliers or a flat-head screwdriver. The heater core should be flushed using a water hose connected to a water supply, and this will cause dirty water to flow at the other end of the pipe.
Repeat the activity until clean water begins to flow from the other end. Then pour coolant inside one of the hose pipes until it comes out at the end and reconnect it. After reconnecting the hoses, inspect the work to see if the AC is blowing hot air or not.
Conclusion
Having read through this article and the many tips and tricks it included, you shouldn’t be worried if your car AC blows hot air and cold air on different sides of the vehicle.
Here are the key information discussed in the article:
- Low lubricant levels will cause mechanical wear in the compressor, so the AC system should maintain an optimum lubrication oil level.
- A clogged condenser can cause hot air to blow on one side of the vehicle, so the blockage should be removed from its drain line.
- A damaged blower motor will cause weak airflow and poor climate control inside the cabin, so it must be replaced.
- Since a damaged blender door actuator also cannot be repaired, it must be replaced to restore consistent cool airflow in the system.
With the information in this article, once you discover that your car AC is malfunctioning, you can diagnose and fix the problem quickly.
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