How to Replace a Car AC Low-Pressure Hose

Date: May 18, 2024

Closed-loop air conditioning systems, used in many modern automobiles, trucks, and SUVs, prevent coolant and refrigerant from escaping outside of the vehicle unless a leak occurs. These leaks are often located in low-pressure or return lines or high-pressure or AC feed lines. Unless additional refrigerant is required, the air conditioner should keep blowing cool air until the connections are tightened. The AC low-pressure hose, however, may have issues and has to be replaced and recharged. While liquid refrigerant is distributed via the AC condenser and dryer by the high-pressure side of the air conditioning system, the low-pressure side is connected to the compressor from the AC evaporator. After the closed-loop cycle, both systems have to cooperate to change heated air into cold air. 

The majority of low-pressure AC hoses are constructed of metal, with flexible rubber hose material used for engine compartment tight spaces. Small holes in the hose might lead to refrigerant leakage, which would be ineffective for the air conditioning system. It is essential to perform regular AC inspections for leaks and repair the damaged components to resolve this problem.

Recognizing signs of a broken AC low-pressure hose.

Symptoms of damage to the low-pressure side of the AC system usually appear sooner than symptoms on the high-pressure side. This is because the cold air is blasted into the car from the low-pressure side. There will be less cold air in the cabin when the leak is on the low-pressure side. The symptoms won't be as obvious at first if the high-pressure hose is the source of the issue.

 Since your car's air conditioning system is closed-loop, you must locate the leak before deciding which parts to replace. When the low-pressure hose is damaged or leaks, these symptoms or warning signs are frequently observed.

The cabin lacks cool air flow: Less cold air entering the cabin is the first and most noticeable indication that there is a leak in the low-pressure line. Since the low side is used to transport the refrigerant to the compressor, issues with the hose typically affect the overall air conditioning system.

There’s refrigerant buildup on the hose: A greasy film frequently forms on the exterior of the low-pressure line if there is a leak originating from the low-pressure side of the air conditioning system. This is because the gaseous refrigerant coming from this side of the air conditioning system is the cause of this. This is usually located on the fittings that attach the compressor to the low-pressure AC lines. The refrigerant will ultimately run out and the air conditioning system will become entirely worthless if the leak is not rectified. This may potentially lead to the failure of other important AC system components.

Adding refrigerant to the AC system causes the sound of escaping refrigerant: When there’s a hole in the low-pressure line, it’s common to hear a hissing sound coming from beneath the car. Currently, there are two popular methods for looking for leaks: 

  • Reach over the pipe and feel around for any refrigerant leaks.
  • Use a dye or refrigerant substance that will reveal the leak’s source when illuminated by a UV or black light.

Causes of AC low-pressure hose failures

Age, environmental exposure, and time are the main causes of low-pressure hose failures. Damage to the low-pressure pipe is quite uncommon. Refrigerant leaks from the system are mostly caused by worn-out or broken seals on the condenser or AC compressor. The AC compressor clutch frequently shuts off automatically, rendering the system inoperable, if the refrigerant level drops too low. Given that the refrigerant is also utilised to cool the system, this lowers the possibility of the compressor catching fire.

 The most frequent locations for AC low-pressure hose failures are the rubber sections of the hose or the connections to the other portions. Due to ageing or heat exposure, the majority of the hose's rubber components may crack because they are bent. Additionally acidic refrigerant may cause the hose to deteriorate from the inside out until a hole appears. The low-pressure hose may potentially sustain damage in the event that the system contains an excessive amount of AC refrigerant. As a result, the hose itself becomes unable to withstand the excessive pressure and either bursts or pops the seal where it connects to the compressor. This scenario is the worst case and is rare.

How to replace a new AC low-pressure hose

After diagnosing the AC leak as a low-pressure hose, order the correct replacement parts and tools. Specialized equipment is required to remove refrigerant and pressure from AC system lines.

The general procedures to replace the AC low-pressure hose are given below. Each AC system has its own distinct characteristics determined by the manufacturer, model, year, and make. Make sure to consult your service manual for precise instructions on safely repairing your AC system’s low-pressure hose. If you are unable to handle it on your own, you can seek the help of professionals like Fasttrack Emarat to fix the issue for you.

Remove battery cables: To replace mechanical components, remove battery cables from positive and negative terminals, ensuring they don't connect to terminals during repair, and power from the battery is always recommended. 

Drain refrigerant and pressure from your AC system: To remove pressure from the AC system, follow these steps:

  1. Remove battery cables and follow the instructions in your vehicle service manual.
  2. The next step is to connect the vacuum pump, manifold system, and empty tank to the vehicle’s AC system, ensuring all components are securely attached.
  3. Secure all lines by opening valves on the manifold, vacuum pump, and empty tank.
  4. Switch on the vacuum pump and wait until both the low and high-pressure lines read zero on the pressure gauges as the system drains.
  5. Refer to your vehicle service manual for specific methods.

Find and replace the leaking low-pressure hose: If you completed the pressure check, it’s important that you note which low-pressure line was damaged and requires replacement. Normally, there are two distinct low-pressure lines. The line connecting the compressor to the expansion valve, commonly made of rubber and metal, is prone to breaking.

Detach AC low-pressure hose from expansion valve and compressor: The expansion valve is connected to the low-pressure lines through two common connections. The AC low-pressure hose connects the expansion valve to the compressor on the left side, but it’s unlikely to be the cause of the leak. Refer to the service manual for specific instructions on connecting and fitting different types of vehicles.

Inspect AC low-pressure hose connections: Make sure the connections to the compressor and expansion valve are secure after replacing the old hose with a new low-pressure line. To tighten new connections, follow the directions in the service manual and make sure each fitting is securely attached according to the manufacturer’s recommendations. If you neglect this, there is a possibility of a refrigerant leak.

Recharge AC system: Each vehicle has a unique process for recharging an AC system after it has been drained, so consult your service manual for guidance.

Don't worry if you can't replace the AC low-pressure line on your vehicle alone. Fastrack Emarat provides expert car AC low-pressure hose replacement services in Dubai. Our skilled specialists will do the task quickly and effectively, guaranteeing that the AC system in your car performs at its best. For professional AC repair service in Dubai, stop by Fastrack Emarat today!