Category: AC compressor

Is my ac compressor working ok

What components should be replaced to avoid any other problems with the new compressor?

 

  • Compressor
  • TXV(Thermal Expansion valve/FOT(Fixed Orifice Tube)
  • Receiver-drier / Accumulator
  • Seals at every connection open(O-rings /washers)
  • Condenser
  • Flush A/C lines
  • Balance compressor oil and A/C components replaced oil
  • Pull a deep vacuum
  • Recharge

The AC compressor should last for the entire life of the car, usually 8-10 years. Before installing a new air compressor we need to investigate what caused the failure in order to avoid future issues.

What causes an air compressor to lock up?

 
Lack of lubrication
Cooling system poor performance
Condenser fan not working or performing poorly
A/C system overcharged
Incorrect type of oil
Low refrigerant charge
A/C system contamination
A/C refrigerant cross contamination (Charging R-134a refrigerant into R-1234YF refrigerant.)
Inefficient condenser
Dirty evaporator core (In the past, not much attention was paid to dirty evaporators. Technicians are now beginning to realize that low evaporator pressures cause high compression ratios.)
 
The compressor’s efficiency can be improved by maintaining the correct working conditions. This involves keeping the suction pressure as high as practical and the head pressure as low as practical within the design parameters.
When a compressor begins to have an internal failure. It often releases debris into the A/C system. The debris created can be metal or Teflon. When enough debris is present, it can become trapped in the various components, and restrict the flow of refrigerant and oil.
After a catastrophic compressor failure the system must be flushed, otherwise the new air conditioning compressor could get damaged by all the debris released by the old locked up a/c compressor.
Most vehicle manufacturers recommend closed loop flushing with refrigerant as a flushing agent. A benefit of this type of flushing is there is no danger of flush contamination, since the flush agent being used is the correct refrigerant for the A/C system.

Fix what is causing the air conditioning compressor to fail.

Some common problems automotive a/c compressors may experience:
1-High head pressures, due to:
1.1-Overcharged ac systems.
1.2-Condenser fan not working at all or working not efficiently enough.
1.3-Clogged up with road debris, condenser core.
1.4-Contaminated a/c systems, with non-condensable gases.
2-Frequent clutch cycling due to:
2.1-Low refrigerant charge.
2.2-Faulty cycling switch.
3-Lack of lubrication or incorrect type and oil viscosity.
4-High resistance in clutch ground circuit.
5-Compressor bearing contaminated with other engine fluids (coolant, power steering…etc)

The AC compressor should last for the entire life of the car,usually 8-10 years.

System maintenance and compressor efficiency

 
The compressor’s efficiency can be improved by maintaining the correct working conditions. This involves keeping the suction pressure as high as practical and the head pressure as low as practical within the design parameters.
A dirty evaporator will cause the suction pressure to drop. When the suction pressure goes below normal, the vapor that compressor is pumping become less dense and gets thin (sometimes called rarified vapor).The compressor performance declines. Low suction pressures also cause the high-pressure gases caught in the clearance volume of the compressor to expand more during the piston’s downstroke.This gives the compressor a lower volumetric efficiency. These gases have to expand to a pressure just below the suction pressure before the suction valve will open. Because more of the downward stroke is used for reexpansion, less of the stroke can be used for suction. Suction ends when the piston reaches bottom dead center. Low evaporator pressures cause high compression ratios.
Dirty condensers also cause compression ratios to rise, but they do not rise as fast as with dirty evaporator.A dirty condenser makes the head pressure to rise. This causes the amount of refrigerant in the clearance volume (at the top of the compressor cylinder) to be greater than the design conditions allow and the compressor efficiency to drop.
If there is a dirty condenser (high head pressure) and a dirty evaporator (low suction pressure), the compressor will run longer to keep the refrigerated space at the design temperature. The overall efficiency drops.
Evaporator core and condenser core maintenance will increase the life of the air conditioning compressor,improve the A/C efficiency and cooling capacity.With regular A/C maintenance we are saving money in the long run and getting the most out of the air conditioning system.

What causes an air compressor to lock up?

 

Auto air conditioning compressor

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What causes an air compressor to lock up?

 

  • Lack of lubrication
  • Cooling system poor performance
  • Condenser fan not working or performing poorly
  • A/C  system overcharged
  • Incorrect type of oil
  • Low refrigerant charge
  • A/C system contamination
  • A/C refrigerant cross contamination (Charging R-134a refrigerant into R-1234YF refrigerant.)
  • Inefficient condenser
  • Dirty evaporator core (In the past, not much attention was paid to dirty evaporators. Technicians are now beginning to realize that low evaporator pressures cause high compression ratios.)

 
 
Analysis of Denso A/C Compressor warranty claims shows that in a quarter of all cases
the use of incorrect oils, such as universal oils or oil mixtures, inevitably leads to seizure and damage. This is because universal oils are PAO-oils or mineral oils with a different viscosity to that of synthetic PAG-oils. PAO-oils do not mix well with PAG-oils and with refrigerant R134a or R1234yf, leading to poor lubrication and increased wear. Installing the ac Compressor without balancing the oil in the system, gives a high risk of liquid lock, due to too much oil in the A/C system! When adding oil to the ac compressor in your car one out of two methods could be used and the right one will depend on the type of compressor. Oil could be added through the ac compressor oil service port or through the low side or intake of the compressor. Always add oil through the oil service port if it comes with one or compressor damage may result.
 
Excessively high temperature and lack of lubrication are the biggest enemies of any automotive a/c compressor bearings. Slipping compressor clutches can generate temperatures as high as 1,200 degrees Fahrenheit; this tremendous amount of heat will quickly melt down the bearing seal. The bearing loses its grease and in the process, before it locks up completely it gets rough and noisy.  Seal could cause the compressor oil to finds it way into the hvac compressor clutch bearing contaminating the grease. The properties of the bearing grease will be changed by this oil contamination causing it a poor compressor bearing lubrication and inevitably internal bearing failure.
 
Leaking air conditioning systems will leak out refrigerant and the oil that resides inside of the compressor creating a huge frictional resistance between the compressor piston and the cylinder leading to an increase in compressor internal temperature
 
Overcharged or improperly vacuumed auto ac systems will create high system pressures and therefore high temperatures.
 
Compressor pressure plate and rotor pulley excessive air gap will cause slippage and rise in temperature.
 
A dirty evaporator will cause the suction pressure to drop. When the suction pressure goes below normal, the vapor that the compressor is pumping becomes les dense and gets thin (sometimes called rarified vapor).The compressor performance declines. Low suction pressures also cause the high-pressure gases caught in the clearance volume of the compressor to expand more during the piston’s downstroke.This gives the compressor a lower volumetric efficiency. These gases have to expand to a pressure just below the suction pressure before the suction valve will open. Because more of the downward stroke is used for expansion, less of the stroke can be used for suction. Suction ends when the piston reaches bottom dead center.
 
 
 

How to save my auto air conditioning compressor?

 

A/C performance test

 
 
This easy test will give you a general guideline to compare against your car’s a/c operation. (This test was specifically performed on a BMW model).
 
 
Switch on air conditioning compressor with A/C button at a vehicle interior of 45 °C /113 °F (measure at the head restraint)
 

On vehicles with MAX-AC button:

  • Activation of  MAX- AC (= maximum cooling power)

On vehicles without MAX-AC button:

  • Set Maximum cooling power by means of following steps:
    • Setting low temperature value
    • Blower setting maximum
    • Stratification maximum cold(4 blue bars)
    • Only ventilation open
    • Close remaining flaps (air outlet only from center fresh air grille, left and right)

 
After 5 min, measure both ventilation temperatures with a thermometer at the same time (center, left and right fresh air grille). The measured temperature must be < 16 °C / 60.8 °F and the difference between right and left may not be greater than 2 °C / °F.
 

How to find an automotive compressor problem, before is too late?

 
Compression ratios are used to compare pumping conditions for a compressor. When compression ratios become too high, the refrigerant gas temperature leaving the compressor rises to the point that oil for lubrication may become overheated. Overheated oil may turn to carbon and create acid in the system shortening the life of the Automotive A/C system.
 
 

R-134a

Ambient temperature

High Side Pressure

Low Side Pressure

90 °F/32°C 250-270 psi /1724-1862 kPa 45-55 psi / 310-379 kPa

 

Calculation:

 
Calculation example:
 

Compression ratio = Absolute Discharge

                             Absolute Suction

 

CR= 250 psig + 14.7 atmosphere

        45 psig + 14.7 atmospheres

 

CR = 264.7

59.7

 

CR = 4.43:1

 
Understanding the A/C compressor compression ratio results.
 
A compression ratio of 4.43:1 would indicate to a service technician that the absolute or true discharge pressure is 4.43 times as great as the absolute suction pressure. Either an increase in head pressure or a decrease in suction pressure will cause higher compression ratios.
 
 

Symptoms of a Bad or Failing AC Compressor

 

  1. Growling noise with compressor disengaged
  2. Whistling noise
  3. Grinding noise
  4. Squealing noise
  5. Rattling noise
  6. Growling noise with compressor engaged
  7. Banging noise
  8. Knocking noise

 
 
Serpentine belt problems usually result from one of these causes: a defective belt tensioner, misalignment of a pulley or defective bearings of any component of the drive system. Worn out drive system belts lead to poor hvac compressor output performance.
 

Can compressor be repaired?

 
The air compressor may be remanufactured or rebuilt. The price range for labor only is $285.00 to $500.00.This is an option many people choose, because of the price difference between a new compressor and a rebuilt one.
 
 

What happens if a compressor fails?

 
The first sign will be no cold air coming out from the vents.
These are all signs that a/c compressor in your car is about stop working or fail:
 
1-Clicking sound from under the engine. (Compressor clutch engaging and disengaging)
2-AC not working.
3-Noise under the engine with the a/c climate control on.
4-Burned rubber smell coming out from the engine compartment.
5-Looking at ac gauges set pressure; typical weak or damaged ac compressor pressures are High side pressure too low and Low side pressure too high.
 
When a compressor begins to have an internal failure. It often releases debris into the A/C system. The debris created can be metal or Teflon. Metal debris can be created from any metal component inside the compressor sefl-desctructing, and Teflon can come from the Teflon seals on the compressor pistons. When debris becomes trapped against the seal, it will damage it and pieces of the seal break apart and travel throughout the A/C system.
When enough debris is present, it can become trapped in the various components, and restrict the flow of refrigerant and oil.
 
After a catastrophic compressor failure the system must be flushed, otherwise the new air conditioning compressor could get damaged by all the debris released by the old locked up a/c compressor.
Most vehicle manufacturers recommend closed loop flushing with refrigerant as a flushing agent. A benefit of this type of flushing is there is no danger of flush contamination, since the flush agent being used is the correct refrigerant for the A/C system.
 
When the A/C system flushing is complete:
 

  • Oil balance the system through the compressor.
  • Reconnect the manifold line to the compressor, or replace the compressor if needed.
  • Install a new orifice tube or TXV.
  • Install a new Accumulator-drier or Receiver-drier

 
 
 

Why did my compressor stop working?

  • Electric or electronic fault of any of the compressor control devices or ac compressor circuit protection device
  • Faulty or wrong signal input to the BCM or PCM.
  • A/C compressor clutch excessive air gap.
  • A/C system too low on refrigerant charge due leakage in the air conditioning system.
  • Compressor clutch coil winding open.
  • A/C head control set switch damage or entire a/c control set damaged.
  • Variable displacement electronically controlled compressor. Valve control damaged.

 
 
 
 

A/C compressor

A/C operation, normal noises.

Normal noises include the sounds of A/C compressor clutch engagement, the blower motor, moving blend air and mode doors, and pressure equalization after vehicle is shut down.

Noises that could indicate the need for a/c compressor service or replacement include:

  1. Growling noise with compressor disengaged
  2. Whistling noise
  3. Grinding noise
  4. Squealing noise
  5. Rattling noise
  6. Growling noise with compressor engaged
  7. Banging noise
  8. Knocking noise

Why is my AC making a weird noise?

Banging noise: If liquid refrigerant enters the compressor, a thumping, banging noise will result.

Knocking noise: Heavy knocking compressor noises come from refrigerant system blockage, incorrect pressures, or internal damage.

Growling noise with compressor disengaged: A worn compressor pulley bearing or clutch bearing will cause a growling noise.

Growling noise with the compressor engaged: A/C compressor internal bearings damage.

Squealing noise: A loose, dry, or worn A/C compressor belt will cause squealing noise. This noise will be worse during acceleration.

Worn or dry blower motor bearings may cause a squealing noise when the blower motor is running

Rattling noise: A loose or worn clutch hub or loose compressor mountings bolt will also cause rattling noise from the compressor.

Knocking noises: This type of noise from the compressor usually indicates internal damage, especially on piston-type compressors. Always check the compressor mounting and brackets before condemning the compressor for noise.

A loose mounting can cause knocking noises from the compressor area that may be mistaken for internal compressor noise.

Grinding noise: When car accessories pulley bearings are failing, they can make this kind of noise.

A/C compressor locked up.European cars

Can I drive my car with a bad AC compressor?

Will a bad AC compressor affect the engine?

A bad compressor could affect the engine in your car. If your compressor’s pulley bearing goes bad, your engine can stall due to the stuck compressor or the serpentine belt may break affecting all the accessories moved by the serpentine belt.

Clutchless variable displacement piston compressors and compressor lock up. 

Clutchless variable displacement compressors have extra protection in case the compressor seizes.In the event  a compressor failure occurs the bridges on the clutch assembly will break and only the pulley will keep running, allowing the engine to keep running.

automotive refrigerant control devices.

What is compressor protection ?

AC compressor circuit protection.

Some compressor clutch circuits contain a thermal limiter switch that senses compressor surface temperature. Some A/C compressor clutch circuits also contain a low-pressure cutoff switch. 

A/C safety switches .

A/C systems have load-sensitive electrical switches; such as the low-pressure switch, high-pressure switch, pressure cycling, and power steering. Not all the switches, however, are used in all vehicles. The pressure switches are used to prevent compressor or component damage in the event of extremely high or low-system pressures.