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Automotive air conditioning compressors require specific types of lubricants. Most 1996 and newer A/C systems use R134a refrigerant and require some type of PAG (polyalkylene glycol) oil for the compressor. If the wrong type of compressor oil or the wrong viscosity compressor oil is used, it may damage the compressor. In fact, the main reason for a newly installed A/C compressor to fail is using the wrong type of compressor oil.

PAO (Polyalphaolefin) oil can sometimes be used as a substitute for certain PAG oils if the compressor manufacturer approves it.

CAUTION: PAG oils should NEVER be used in hybrid vehicles because it is electrically conductive. POE (polyol ester) oil is usually specified for hybrid cars that have electrically-driven A/C compressors because it is non-conductive. Using the wrong oil may allow current to short circuit back through the A/C compressor, creating a shock hazard.

Mineral oil should only be used in older R-12 A/C compressors because R-12 will not mix with R-134 refrigerant.

"Universal" A/C compressor oils are often PAO-based and are not the same viscosity as the PAG oil recommended for a specific type of compressor. This can lead to poor lubrication and premature compressor failure.

Newer vehicles with R-1234yf A/C systems require a

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Should you flush or not flush a dirty condenser? When an A/C system contains sludge, compressor debris or other solid contaminants, what is the best course of action?

condenser

 

Unfortunately, there is no simple answer to this repair dilemma because the answer depends on the circumstances, the vehicle, the contaminants in the system and the style of the condenser.

Condensers are trash collectors. Any debris that comes out of the compressor goes straight into the condenser. It is a low spot in the system so debris and oil naturally collect in the condenser. But the debris does not stay put. Refrigerant flowing through the condenser can pick up debris and carry it to the orifice tube, expansion valve or back to the compressor. Debris can plug up the orifice tube or expansion valve, causing a blockage and loss of cooling. Such blockages also can prevent the circulation of oil in the system, starving the compressor for lubrication.

If the condenser is dirty, why not just replace it? That is what many experts recommend.

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a/c compressorThe compressor is the heart of the refrigeration circuit. It pumps and pressurizes the refrigerant to move it through the A/C system. Compressors work hard and run hot, up to several hundred degrees and several hundred pounds per square inch of internal pressure. They rely on only a few ounces of lubricant to keep their parts moving. If the lubricant is lost because of a leak, or the lubricant breaks down due to contamination, the compressor will not last. Sooner or later, the compressor will call it quits.

The most common symptom of a compressor failure (besides no cooling) is a seized compressor. It will not turn when the magnetic clutch engages, and you may hear squeals of protest from the drive belt. Or, the belt may have already broken or been thrown off its pulleys.

Loss of lubrication is unquestionably the most common cause of compressor failure. This can happen when there is a refrigerant leak somewhere in the system that allows refrigerant and oil to escape. Typical leak points are hoses, hose and pipe connections (O-rings and flange gaskets), the evaporator, condenser or the compressor shaft seal.

How do you align an "unalignable" vehicle? It depends on what makes it unalignable. Front toe on virtually every car and truck is adjustable. But as we all know, there are a lot of vehicles that have no factory adjustments for front camber, caster, rear camber or toe. If the wheels are out of the factory specified range and need to be corrected, it may seem like mission impossible, especially if you are not aware of any aftermarket alignment aids such as shims, eccentrics, offset bushings, strut plates or other modifications for the particular vehicle you are trying to align.

The secret to aligning these kinds of "unalignable" vehicles, therefore, is taking your vehicle to a shop that has an up-to-date alignment machine.

CHRYSLER WHEEL ALIGNMENT PROBLEMS

Chrysler Cirrus, Dodge Stratus and Plymouth Breeze have no factory front camber adjustments. Chrysler says no adjustment is needed because these cars are built to such exacting tolerances. Yeah, right. We have heard that one before. Either somebody goofed or Chryslers bean counters axed the camber adjustment to save a few bucks on every car they build. In any event, we all know that some of these cars will likely require

Ever take a long trip in a vehicle with a steering pull problem? Having to maintain constant pressure on the steering wheel can very tiring, not to mention hard on the tires. A vehicle with a pull problem is a vehicle that is fighting the forces of nature. Something is amiss and is causing the vehicle to follow a path other than a straight one.

There are actually several different types of steering pull: a steady pull, a pull that only occurs after turning (memory steer), or a pull that only occurs under certain driving conditions such as bump steer or torque steer.

An off-center steering wheel may or may not accompany a pull (which we'll cover shortly). Other times the pull may be more of a "drift" or steering wander to one side or the other. So let's look at some of the common pull-related conditions along with their causes and what you have to do to eliminate them.

 

STEADY PULL

This is a condition where the vehicle continually pulls or drifts to one side while traveling straight. The driver typically has to maintain steady pressure on the steering wheel

Have you ever been confronted by a vehicle with a bad attitude? The kind of attitude we're talking about here is not a chip on the shoulder, but a physical attitude that's not what it should be. The chassis may be sagging or slightly askew thanks to the unbalanced forces of gravity that are working upon it. The underlying cause of this kind of bad attitude is usually one or more sagging springs, and the way you detect it is by measuring ride height prior to doing a wheel alignment.

Ride height problems are not always obvious, and may be overlooked unless a vehicle is leaning like a battleship that's taken a torpedo, or is tilting like the Titanic on its final plunge. It's hard to see variations in ride height if the difference is only an inch or two. You can compare the height of the fender wells on both sides to see if the suspension is leaning or not, but a simple comparison won't tell you if the overall chassis height is correct or not. And with the nose-down aero attitude of so many cars today, it's impossible to tell if the vehicle has the right attitude

Strut suspensions are named after Earl S. MacPherson who invented the first strut suspension back in the 1950s. The strut suspension is an independent front suspension with a lower control arm and a strut assembly in place of the upper control arm. It is an alternative to the SLA (Short Long Arm) suspension that was used up until the 1980s on most cars. Struts suspensions came into widespread use in the 1980s along with front-wheel drive, and is used on most passenger cars and minivans today. SLA suspensions are still used on most fullsize pickup trucks and SUVs which have heavier loads to carry.

What Does A strut Do?

The strut�s role in a MacPherson strut suspension is to (1) support the weight of the vehicle via the spring around the strut, and (2) to serve as the upper steering pivot for the knuckle. This eliminates the need for an upper control arm and ball joint (except for "wishbone" strut suspensions which still use upper control arms). In a wishbone suspension, the strut is attached to the lower control arm instead of the steering knuckle, and an upper control arm serves as the upper steering pivot for

Has this ever happened to you? You have the alignment checked on a car or truck and found that it was within the acceptable range of specs for the application, but it does not steer straight. It is a common enough problem, so keep reading any maybe we can straighten things out for you.

As anybody who has spent much time under an alignment rack knows, the range of factory tolerances that are included in the data banks of most electronic alignment equipment today (as well as alignment reference books) may not be tight enough for every vehicle you are apt to encounter. The alignment specs that everyone uses are compiled from information supplied by the vehicle manufacturers, and are based on the vehicle's suspension geometry, drivetrain configuration, handling characteristics, weight distribution, average loading, etc. As long as a vehicle is within the range of specs listed, wheel alignment should be acceptable under most circumstances. But sometimes it is not. Some vehicles are more sensitive to slight variations in alignment than others, just as some drivers are more sensitive about how their car or truck steers and

Wheel alignment refers to the geometrical relationship of the wheels to the vehicle itself, to each other and to the road. Ideally, all four wheels should be aimed straight ahead, parallel to each other, perpendicular to the road and perpendicular to their respective axles. This will produce the least amount of rolling resistance, the least amount of friction, the least amount of tire wear and the greatest traction. The basic alignment angles we're talking about here are toe, camber and caster.

TOE WHEEL ALIGNMENT

Toe is the most important wheel alignment angle because it has the greatest effect on tire wear. Toe refers to the parallelism between the wheels as viewed from above and is usually measured in inches or millimeters. When both front wheels are aimed straight ahead and the distance between the leading edges of both front tires is exactly the same as the distance between the trailing edges, the wheels have "zero toe" and are theoretically aligned. We say in theory because toe alignment changes when the vehicle is being driven.

The joints and sockets in the suspension and steering linkage all have a little play, which when added together can allow wheel alignment to

HOW AUTOMATIC CLIMATE CONTROL DIFFERS FROM MANUAL AIR CONDITIONING

Manual air conditioning systems are just what the name implies: they require he A/C temperature settings to be adjusted manually. Manual A/C systems have an on-off switch, a temperature control knob or slide switch and a knob or switch for adjusting fan speed.

With a manual A/C system, you turn on the A/C when you want cool air and select a temperature setting and blower speed. If the air gets too cold, you turn down the blower speed or change the position of the temperature setting. If the air isn't cold enough, you crank it all the way up.

The temperature slide switch on most manual systems is connected with cables or vacuum hoses to the airflow control doors inside the HVAC (heating ventilation air conditioning) unit under the instrument panel. Changing the temperature setting opens or closes the doors to increase or decrease airflow through the A/C evaporator. It is a relatively simple, trouble-free control system that does not require a lot of complicated electronics.

Automatic temperature control systems, by comparison, can be very complicated (and troublesome). These type of systems control both heating and cooling with a

When your car or truck has an air conditioning problem and needs service, what should you do? If your A/C system only needs some refrigerant, you can probably recharge the a/c system yourself. But if you are having cooling problems, leaks or electronic control problems, you should probably seek out a repair facility that specializes in air conditioning service work.

Our advice is to seek out a repair facility that is a member of MACS, the Mobile Air Conditioning Society. MACS is a non-profit trade association for repair shops that do air conditioning service work. MACS promotes training, education, professionalism, and most importantly "Best Practices" for servicing and repairing your vehicle's air conditioning system.

Since 1991, MACS has assisted more than one million technicians to comply with 1990 Clean Air Act requirements for certification in refrigerant recovery and recycling to protect the environment.

Recently, the Climate Protection Partnership division of the U.S. EPA teamed up with MACS to publish and promote six mobile air conditioning best service practices checklists. These checklists are written for professional technicians to help them environmentally safe and technically proper air conditioning service and repairs.

If you drive an older vehicle (pre-1994), the air conditioning system contains R-12 refrigerant (Freon). As long as the A/C system has no leaks and it cooling normally, there is no need to convert from R-12 to the new "ozone safe" R-134a refrigerant. But if your A/C system has lost it's charge because of a leak, collision damage, or the need to open it to replace a compressor, hose or other component, you may have to convert from R-12 to R-134a when you recharge the system

Why? Because R-12 is no longer produced in the U.S. Supplies of recycled R-12 still exist, and some R-12 is still brought in from offshore suppliers. But it is hard to find and expensive. That's why many people simply recharge their older R-12 air conditioning system with R-134a after repairs have been made.

R-134a Retrofit Conversion Costs

Does it make economic sense to retrofit an older vehicle to R-134a if the A/C system has lost its refrigerant charge or needs major repairs? The older a vehicle gets, the more it depreciates. By the time it is 15 or more years old, it may only be worth a few hundred dollars.

Flammable refrigerants are illegal to use in an automotive air conditioning system. There are some exceptions, such as the new R1234yf refrigerant, which is mildly flammable but only under certain conditions. Flammable refrigerants may also be used in the trailer refrigeration units on heavy duty trucks. But other than these, no flammable refrigerant should ever be used in a car or light truck A/C system.

Flammable Refrigerant Fire Hazards

Propane, butane and a number of other hydrocarbon mixtures and blends actually work quite well as refrigerants, with cooling characteristics similar to R-12, R-22 and R-134a. But if the evaporator inside the passenger compartment develops a leak, the flammable vapor may create a potential for a fire or explosion. Do you really want to risk being cremated while driving your vehicle?

Another thought to keep in mind is what happens if your vehicle is involved in an accident. The A/C condenser sits right in front of the radiator and contains high pressure refrigerant vapor and liquid. If the condenser is ruptured in a frontal collision (which it often is), high pressure flammable vapor will be released, almost guaranteeing an underhood fire!

Do you really want to risk your life

What the future holds for automotive refrigerants is uncertain, but changes are happening and more changes are coming. R-134a refrigerant contineus to be used in many late model vehicles, but many new cars are now being equipped with A/C systems that use R-1234yf refrigerant. Other refrigerants may also be coming as R-134 is gradually phased out in the years ahead. The Europeans want to phase out R-134a in all new vehicles by 2017. The European rules require any new refrigerants must have a global warming potential of less than 150. The U.S. EPA also wants car makers to switch to a different refrigerant to lower the overall carbon emissions of the vehicle fleet. Carbon credits will be given to auto makers who make the switch to a refrigerant that has a lower Global Warming Potential (GWP). Though R-134a poses no danger to the ozone layer if it escapes into the atmosphere, it is a "greenhouse gas" with a fairly high global warming potential of 1300 (compared to 1 for carbon dioxide, which is nature's own greenhouse gas). A leak that allows only an ounce or two of R-134a to escape into the

Auto makers are slowly moving toward a new refrigerant for automotive air conditioning systems. The new refrigerant is R-1234yf (HFO-1234yf), and it will be phased in slowly over time starting with some 2014 model year vehicles.

R-1234yf has cooling properties that are similar to R-134a, which has been used as an automotive refrigerant since it was introduced back in 1994 to 1995 to replace R-12. R-134a contains no CFCs, which are harmful to the Earth�s protective ozone layer, but it does retain heat well and has a relatively high Global Warming Potential (GWP) rating of 1410.

IMPACT ON GLOBAL WARMING

Automotive refrigerants that leak out of A/C systems contribute very little to the overall global warming problem, only about 0.14% according to scientific estimates. Even so, when you multiply the millions of vehicles that are AC-equipped times even a small amount of refrigerant leakage over time, the numbers can add up. Some would argue that switching to a new refrigerant is unnecessary and will hardly make a dent in climate change. Others argue that it is all a conspiracy by DuPont and Honeywell to monopolize the world automotive refrigerant market by getting regulators

Seems like everybody is trucking these days. And why not? Most people perceive trucks as a better value for their money. They like the size, visibility and utility a truck provides as well as the "outdoorsman" image conveyed by many sport utility vehicles (SUVs) and sport trucks. Many of today's trucks also have car-like ride and handling and come fully equipped with all the amenities, which makes them more appealing to a wider range of buyers. So it is no wonder there is more trucks on the road today.

Despite their rugged image, though, trucks and SUVs are just as vulnerable to tire wear problems and misalignment as cars. In fact, alignment is even more of a concern with trucks and SUVs because the tires tend to be larger and more expensive than those on most cars. That's why an annual alignment check is often recommended. An alignment check should also be performed anytime a vehicle has a tire wear problem or has been experiencing a steering pull or other steering or handling related problem.

TRUCK ALIGNMENT TIPS

Regardless of the type of truck that is being aligned, there are some general rules to keep in mind:

DROP-IN ALTERNATIVES FOR R-12 REFRIGERANT?

Though a number of alternative refrigerants are marketed as "drop-in" replacements for R-12, there is really no such thing as a true drop-in replacement. The reason why is because Federal law prohibits the topping off A/C systems with ANY refrigerant that is chemically different from what is already in the system, unless all of the old refrigerant is first removed so the system can be converted to the alternative refrigerant.

There are, however, a number of alternative refrigerants that can be used in older vehicles with R-12 A/C systems, and most have been reviewed and approved by the EPA for retrofitting older R-12 A/C systems. Approved refrigerants must meet the EPA's SNAP (Significant New Alternatives Policy) criteria for environmental acceptability and usage.

NOTE: The SNAP rules prohibit the use of flammable refrigerants (propane, butane and similar hydrocarbons) in mobile A/C systems because of their hazardous nature, and the SNAP rules prohibit the use of any other refrigerants that contain ozone-damaging CFCs. for more information about flammable refrigerants, Click Here.

APPROVED ALTERNATIVE REFRIGERANTS

There are number of alternative refrigerants from which to choose. One is R-134a, which is the ONLY alternative

A/C COOLING PROBLEM?

The most likely cause of an automotive air conditioner cooling problem is no refrigerant in the system. If the refrigerant has escaped past a leaky compressor or O-ring seal, leaked out of a pinhole in the evaporator or condenser, or seeped out through a leaky hose, the leak needs to be identified and repaired before the system is recharged.

On many systems, the compressor will not turn on if the refrigerant is low because the "low pressure safety switch" prevents the compressor clutch from engaging if system pressure is low. This protects the compressor from possible damage caused by a lack of lubrication.

One of the first things you should check, therefore, is compressor engagement. If the compressors magnetic clutch is not engaging when the A/C is turned on, the problem may be a blown fuse or a wiring problem. If the fuse is blown, replacing it may restore cooling temporarily. But the underlying reason for the fuse blowing in the first place needs to be identified and corrected to prevent the same thing from happening again.

If the magnetic clutch is receiving voltage but is not engaging the compressor, the clutch is defective

Is you car's air conditioner blowing warm air only and no cool air? Your A/C cooling problem could be caused by any of the following:

Your A/C system may have lost its charge of refrigerant. This is probably the most common cause of a no cooling problem. Another possible cause of no cooling may be that your A/C compressor is not be engaging when you turn on the A/C. This can be caused by an electrical fault in the A/C compressor circuit or the magnetic clutch that drives the compressor. Another cause could be an internal obstruction inside the refrigerant circuit that is preventing refrigerant from circulating inside the A/C system. Another possibility might be a blend air door inside the HVAC unit that is stuck in the HEAT position and is preventing air from flowing through the A/C evaporator.

Compressor Checks

Start with the compressor. Does it engage when you turn on the A/C?

If so, the compressor is working and the A/C system probably contains enough refrigerant to make cold air, so the problem is inside the HVAC unit. Replace the motor that controls the blend air door (this is a

You should check your car's A/C system BEFORE hot weather arrives to make sure it is working properly and blowing cold air. The following tips on how to check your car's air conditioning system has been provided by the Mobile Air Conditioning Society (MACS):

Note: Always be extremely careful any time you are under the hood while the engine is running. Stay away from all rotating components with your hands, clothing, and hair, and always wear eye protection around a running engine.

1. With the engine running, does the compressor clutch engage when the A/C is switched on? If it does not, this usually indicates a low (or empty) refrigerant condition, or an electrical problem. Also, listen for rapid clicking or cycling noises at the compressor when the A/C is switched on. If this is happening, it could also indicate low refrigerant or some other problems. Have it checked by your service technician. (Note: Some A/C systems prevent compressor clutch engagement in low temperatures, typically at or below 40� F.)

2. Is the A/C system blowing cold air? Luke warm air or air that