A/C refrigerant cross contamination (Charging R-134a refrigerant into R-1234YF refrigerant.)
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.
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.
High Side Pressure
Low Side Pressure
250-270 psi /1724-1862 kPa
45-55 psi / 310-379 kPa
Compression ratio = Absolute Discharge
CR= 250 psig + 14.7 atmosphere
45 psig + 14.7 atmospheres
CR = 264.7
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
Growling noise with compressor disengaged
Growling noise with compressor engaged
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.
Defrost Mode.Damage to compressor due to low refrigerant charge.
On many vehicles, by selecting the defrost position on the controls, it will also activate the A/C compressor. Cooling the air with A/C first will remove more moisture from the air so it can do a better job clearing the windows.If the A/C system is not functioning correctly this ability will be lost. If your A/C system is not working 100%,with low refrigerant charge over the winter months, you’re not getting the refrigerant oil back to the compressor which is damaging it all winter season that will lead to costly repairs in the spring time. If you run into any issues regarding this system have a professional mechanic from Auto A/C Repair. help you diagnose and fix it.
Call Auto A/C Repair LLC. !
To check the auto a/c compressor compression ratio, note on paper the low and high side gauge readings and add atmospheric pressure to both readings. Divide the high side reading (with the atmospheric pressure added) by the low side reading (with the atmospheric pressure added).The result should be between 6.5:1 and 7.5:1. A compression ratio of 8:1 or higher may cause compressor failure. Learn Moreâ€¦
The A/C compressor is considered the heart of the refrigeration system. Compression ratio is the technical expression for pressure difference. Compression ratios are used to compare pumping conditions for a compressor and is an efficient way to evaluate the health of an air conditioning compressor.
If the A/C system operating pressures of your car gives you out of range values CALL US! We come to your place in Miami-Dade. Consider Auto A/C Repair LLC, always near your location!
How to find an auto ac compressor problem, before is too late?
Check for high compression ratios. To check a/c compressor compression ratio, note on paper the low and high side gauge readings and add atmospheric pressure to both readings. Divide the high side reading (with the atmospheric pressure added) by the low side reading (with the atmospheric pressure added).The result should be between 6.5:1 and 7.5:1. A compression ratio of 8:1 or higher may cause compressor failure.
The A/C system is designed to provide the passenger compartment with low temperature and low humidity air. During periods of high heat and humidity, an A/C system will be more effective in the Recirculation mode (MAX-A/C).
How cold should my AC be at the vent in my car?
A performance test is the best way to determine whether the system is performing up to design standards. This test also provides valuable clues as to the possible cause of trouble with the A/C system.
How do I check the temperature of my car AC?
Operate the heating-A/C system under the following conditions:
1-Engine at 1,000 rpm at operating temperature
Door and windows closed
2-Transmission in PARK or NEUTRAL with parking brake set (depending on transmission application)
3-A/C-heater controls set to recirculation mode (MAX A/C), full cool, panel mode, high blower and with A/C compressor engaged.
4-Insert a thermometer in the driver side center panel air outlet and operate the A/C system until the thermometer temperature stabilizes.
5-Compare the air temperature at the center panel outlet and the A/C compressor discharge pressure (high side) to the A/C Performance Temperature and Pressure chart.
The A/C system in your car is a closed sealed system. It may never need to be recharged. The refrigerant inside the system is pressurized by the hvac compressor ,recirculated and reused in a closed loop infinite system. The Freon(refrigerant) will change from vapor to liquid and back constantly for as long as the system is running.
The R-134a/R-1234yf install in your car is in charge of moving the unwanted elevated temperature of one room or space (the cabin inside your car ) to the outside ambient temperature where it has no impact. To accomplish this task properly a factory calculated range amount of refrigerant needs to be running inside the system.
You need to get your AC system recharged as soon as the total amount of refrigerant is too low to carry the heat from inside your carâ€™s cabin to the outside of the vehicle.
100 % sealed air conditioning system does not exist. All a/c systems leak, and this condition is taken into consideration when the a/c charge amount is calculated when designing the system. Some amount of refrigerant loss could develop over time, but it is a minute amount, and it should not affect system operation.
How do I know if my ac in my car needs to be recharged ?
There is not a periodic service interval that you need to follow to recharge your air conditioning system. This service is system dependent, meaning every car will have unique needs for freon(refrigerant) recharge.
The first sign that could indicate that you need to recharge the refrigerant in your carâ€™s ac system is when the system begins to cool less than it used to.
SIGNS OF LOW REFRIGERANT CHARGE:
Poor A/C performance. A/C not cooling down the vehicle
One Side of the car cooling more than the other side.
Back of the car cooling more than the front.
A/C compressor short cycling. A/C compressor turning on and off fast.
Frost in a/c lines.
Visible refrigerant (Freon) leaks.
A/C SYSTEM LOW ON REFRIGERANT CHARGE
Low refrigerant could mean low oil circulating and improper lubrication of the hvac compressor. Therefore when there has been a refrigerant leakage big enough the compressor gets to the point where there is not refrigerant to pump and then it pumps out the oil that lubricates the compressorâ€™s internal components. Failure of the a/c compressor will result if the ac system is not recharged, and oil balanced properly.
The refrigerant in the automotive system is the substance which not only transfer heat from the passenger compartment in the vehicle to the condenser outside of the car and then released the heat into the atmosphere, but it also cools the compressor down reducing the total heat of compression preventing the compressor from building up excessive pressure and temperature. A poor lubricated compressor could be operating in temperatures that could get up to 800 F
ELECTRONIC CONTROLLED VARIABLE DISPLACEMENT CLUTCHLESS COMPRESSOR AND LACK OF LUBRICATION
Electronic controlled variable displacement compressors could be clutch or clutch-less designs. The ac compressor has a swash plate that rotates to reciprocate pistons, which compress refrigerant. The swash plate is allowed to change its angle which changes the stroke rate of the piston. They are electronically controlled using sensors and an Electronic Control Module (ECM)
Electronic controlled variable displacement compressor is always running even when the a/c is off. The ECM changes the rate of displacement, but the compressor is spinning connected to the drive belt without any clutch to disengage.
Lubrication occurs by using a sump in which the connecting rod splashes oil around the inside of the compressor. Some automotive air conditioning compressors use an oil pump to circulate the oil, like an engine lubrication system. Lubrication is accomplished while the ac compressor is running and there is refrigerant and oil circulating back to the compressor.
The (ECVD) clutch-less compressor should not be operated without refrigerant in the system to carry lubricant.
EXPENSIVE MISDIAGNOSIS AND UNNECESSARY COMPRESSOR REPLACEMENT
These (ECVD) clutch-less compressors do not have a conventional clutch, meaning the compressor shaft turns all the time driven by the accessory drive belt, even when the a/c is commanded off from the hvac temperature control assembly panel!
ECV CONTROL DIAGRAM
2015 HYUNDAI ELANTRA GT 2.0L
Source: ALLDATA Repair.
Variable Swash Plate Compressor
The internally controlled variable swash plate compressor changes the swash plate angle by a MCV (Mechanical Control Valve) in accordance with fluctuation of a suction pressure.
The externally controlled variable swash plate compressor changes the swash plate angle by an ECV (Electric Control Valve) in accordance with an electrical signal from the heater & A/C control unit.
HOW TO QUICKLY DIAGNOSE CLUTCHLESS COMPRESSOR FAILURE
Without the right tools This new compressor output control technology can make it difficult to determine if the poor ac performance is being caused by a computer control malfunction or another problem in the refrigeration system or cooling system of the vehicle. This can result in an expensive misdiagnosis and unnecessary compressor replacement.
These are different tools that could be used for correct testing a diagnose of this units:
1. A scan tool and checking PWM signal from the module to the ECV compressor .
2. Handheld ECV Compressor tester unit to manually control the ECV on the compressor and increase or decrease (PWM) the pumping capacity of the air conditioning.
3. A scope can be used by carefully back probing the connector to the control valve and connecting the scope leads to the two wires and check the PWM wave signal
LOW REFRIGERANT AND LOW OIL CONDITION COULD LEAD TO AC COMPRESSOR DAMAGE
With a large refrigerant undercharge, oil is pumped out from the compressor and becomes trapped in the evaporator or other ac components of the system and is unable to properly return to the hvac compressor. The amount of oil in the compressor can get down to dangerously low levels creating excessive heat and, in most cases, leading to failure of the unit. Some Air conditioning tests has shown that with an undercharged ac system, the oil amount in the compressor was reduced by over 57%.
Car A/C air conditioning compressor clutch bearing.
Automotive a/c compressor clutch bearing failures are usually caused by system problems and not the bearing itself. Replacing the noisy bearing without finding the root of the problem and fixing it permanently will only lead to premature damage of a new component and a waste of time and money. Seals, compressor shaft and bearing could share the same enemy, heat.
What could cause damage to the ac compressor bearing in my car ?
Excessively high temperature and lack of lubrication
Slipping compressor clutches
Over tensioned manual belt tensioners
A leaking compressor shaft seal
A leaking compressor shaft seal could cause the compressor oil to find its 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.
What could cause the ac system in my car to buildup excessive high pressure and temperature ?
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 elevated temperatures.
Compressor pressure plate and rotor pulley excessive air gap will cause slippage and rise in temperature.
Replacing just the bearing
A/C compressor factory bearing defects will not need more than a few hours of compressor operation to become evident. Rarely the bearing itself is the culprit.
Proper lubrication is a must for ac compressor long life. When the a/c compressor is operated ,oil gradually leaves the compressor, and the oil is circulated through the entire ac system together Â with the refrigerant. After the air conditioning system is operated for the first time an oil balanced condition is reached in which a certain amount of oil is retained in the compressor and a certain amount is re-circulated through the ac system components with different amounts of oil depositing in them . If a component of the system is replaced after the system has been operated, we need to compensate for this by adding oil to the new replacement ac part.
HOW AN OVERCHARGE/UNDERCHARGE A/C OIL CONDITION AFFECT THE A/C SYSTEM?
Too much oil in the a/c system could result in extremely high head pressures which will cause poor air conditioning performance and premature wear and failure of the hvac compressor. If there is a surplus of oil in the system, too much oil circulates with the refrigerant ,causing the cooling capacity of the system to be reduced and the compressor head pressure to increase. Too little oil results in poor lubrication of the compressor and an increase in the heat of compression which shorten the life of the ac compressor.
OIL BALANCING AN AC SYSTEM
When there has been excessive leakage of refrigerant, or it is necessary to Â replace a component of the refrigeration system oil balancing is necessary to assure that the total oil charge in the system is the correct one after the leak has been repaired or the new ac part is installed in the car.
HOW TO OIL BALANCE MY CAR AC SYSTEM
The recommended procedure step by step
Measure the oil recovered from the system while recovering the refrigerant prior to part replacement
Drain and measure the oil left in the old part
Drain the new part(if factory oil-prefilled)
Refill the new part with the same amount of oil removed from the old part and the amount of oil recovered from the system
WHAT TYPE OF OIL ACCORDING TO TYPE OF REFRIGERANT R-12 R-1234YF AND R-134a
The refrigerant oil required by the automotive ac system depends on a number of factors ,but it is primarily dictated by the type of refrigerant used in the system.R-12 car systems used a mineral oil. Mineral oil mixes well with R-12Â without breaking down and losing its lubrication characteristics. Mineral oil however cannot be used Â to lubricate ac systems with R-134a refrigerant.R-134 systems require a different synthetic oil,polyalkylene glycol (PAG).There are different blends of PAG and POE oil; always use the recommended by the vehicle manufacturer or the replacement part manufacturer.
The lubricant oil used in automotive air-conditioning systems is a non-foaming, sulfur free grade specially formulated for use in cars a/c systems. New refrigerants like R-1234yf might use PAG 46 and are backwards compatible for use with R-134a systems, but the R-134a old PAG 46 oils are not forward compatible with R-1234yf systems.
OIL RECHARGE AMOUNTS
REFRIGERANT OIL Recommended PAG oil: DENSO ND-OIL 8 Â
Add the recommend refrigerant Â oil in the amount listed if you replace any of the following parts:
A/C condenser(including receive Dryer.
25 mL (5/6 fl oz)
40 mL (1 1/3 fl oz)
Line or hose
10 mL (1/3 fl oz)
10 mL (1/3 fl oz)
25 mL (5/6 fl oz)
For A/C compressor replacement, subtract the volume of oil drained from the removed A/C compressor from 82 mL (2 3/4 fl oz), and drain the calculated volume of oil from the new A/C compressor: 82 mL (2 3/4 fl oz) ďĽŤ Volume of removed A/C compressor = Volume to drain from new A/C compressor. NOTE: Even if no oil is drained from the removed A/C compressor, do not drain more than 50 mL (1 2/3 fl oz) from the new A/C compressor.
Oil in the A/C system is essential, primarily to lubricate moving parts, i.e., the compressor. It also enables heat to travel and dissipate from the compressor. As with refrigerant, oil in the A/C system must keep its chemical stability.
Insufficient lubrication due to the wrong type of oil and viscosity is the second most frequent reason for A/C compressor damage and failure.
Distinct types of a/c oil like PAG,POE or mineral oils with a different viscosity do not mix, leading to poor lubrication, damaged seals and increased automotive air conditioning compressor wear
The use of the wrong type of oil could result in the hvac compressorâ€™s piston rubbing against the cylinder surface. If the oil is too thick, it is unable to properly lubricate the tight space between the cylinder wall and the piston. Wrong oil viscosity can result in more internal friction, leading to an increase in compressor temperature and inevitably compressor damage.
Blending or mixing of diverse types of oils may result in a new different type and oil viscosity. This oil contamination build-up to the point where it can block the flow of refrigerant and oil, leading to poor lubrication and seizure of the compressor and major system failure.
Refrigerant moving oil and cooling down the A/C Compressor
it is extremely important that the engine not be run on a vehicle with a clutch less compressor if there is no refrigerant in the A/C system. This is because the compressor depends on refrigerant to carry lubricant inside of it.
How much oil should I add after a/c compressor replacement ?
After the refrigerant system has been charged and ran at the factory, the refrigerant oil in the A/C compressor is dispersed throughout the refrigerant system. The A/C receiver/drier, A/C evaporator, A/C condenser and the A/C compressor will each keep a significant amount of the needed refrigerant oil.
The refrigerant oil level in a new A/C compressor must first be adjusted prior to compressor installation.
Oil balancing the a/c system:
Measure the oil recovered from the system by recovery/recycling/recharging station.
Drain and measure the oil left in the old compressor using a beaker.
Drain the new compressor and refill it with the same amount of oil removed from the system and old compressor .
For Example :if 2 oz of oil are recovered from the system and 2 oz of oil was drained from the old a/c compressor, drain the new replacement a/c compressor and then add 4oz of the proper oil type and viscosity to the compressor before installation.
Installing the ac Compressor without balancing the oil in the system, gives a considerable 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.
Most reclaim/recycling recharging stations will measure the lubricant being removed during recovery. This amount of lubricant should be added back into the system after the repairs are done.
How could the oil in my carâ€™s A/C system be low?
Leaking automotive air conditioning systems will leak out refrigerant and the oil that resides inside of the compressor.
Refrigerant oil must be added when an A/C condenser, A/C receiver/drier or A/C evaporator is replaced
Refrigerant oil loss will be evident at the leak point by the presence of a wet, shiny surface around the leak.