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Your best source for complete troubleshooting and diagnosis information on auto A/C systems. Our information provides proper repair, recharge, service and maintenance procedures for all automotive air conditioning systems. Regardless if you have a current CCOT (cycling clutch orifice tube) system or an expansion valve and POA valve system, we've got the information you need. From step-by-step help on retrofitting and recharging to complete A/C compressor or component replacement, our A/C manuals provide you a quick and easy methods that have been proven helpful to everybody from the apprentice to the professional.

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Replacing your auto A/C Compressor:
Here's a great 'step-by-step' or 'how to' guide to replace your auto A/C compressor.
If you're not doing the work yourself, this information will provide you a much better understand what the auto service shop is trying to explain

Potentially one of the most costly auto A/C repairs is when you have to replace the A/C compressor. If you're facing that situation now, it's really important that you understand all the steps that must be followed in order to do the job properly and get warranty on your replacement compressor. Keep in mind that the 'steps' we talk about apply to either new or remanufactured compressors, so there is no difference. You will also find this information of interest if you're having the work completed by a service shop (or if you're shopping for a service shop). We'll try to eliminate all the technical terms to make it easier to understand.

What's really important to understand before you start is that the A/C system is just that... it's a system! That means it's only as good as the weakest link. It also means that all the components in the system must work together.

To start, let's have a look at some of the components you should really pay attention to when you're replacing the A/C compressor. They are:
1) the condenser
2) the accumulator or receive drier
3) refrigerant or compressor oil
4) orifice tube or expansion valve (also called a TXV)
5) hose or line assemblies
6) Before you finish, you must flush the A/C system.
You should also give serious consideration to having an in-line filter installed. (More about that later) and you may still have to retrofit the A/C system too!

Let's start by understanding what happens when the A/C compressor fails and how it effects the different parts of the system. We will detail the functions of these various parts and also explain how a blown or seized A/C compressor can effect them. That way you'll have a real good understanding of how to go about the replacement of the compressor or be able to better understand what the service shop may be trying to explain. Remember, we're going to keep the technical jargon out so it's going to be easy to follow, ok?

To start, remember that the A/C system is a sealed system. When a compressor fails (usually because of the lack of oil flow to the compressor) the internal parts of the compressor 'break up' and are pushed throughout several parts of the system. This contaminates the system and those parts. Before replacing the compressor, several other A/C parts have to be checked or changed. Here's why.

The Condenser:
The A/C condenser performs pretty much the same function as an engine radiator, but the condenser cools the refrigerant (or freon) in the auto A/C system. Typically, the A/C condenser should be flushed to remove any debris. The flushing of the system will remove contaminated compressor oil and debris scattered throughout the system.
Auto A/C condenser designs are critical to the performance of your A/C system. Did you know that some condensers can not be flushed! In more current vehicle applications using high efficiency condensers, you should understand that they may not be able to be flushed. Why? The passages are simply too small and much of the debris gets lodged into the tube openings. In short, it's just impossible to remove all the debris from these condensers designs. The photo on the left shows a 'cut away' cross section of a typical high efficiency A/C condenser. You can see for yourself that the tube openings are extremely small.

SERVICE Required: Depending on the actual design of the A/C condenser, it may have to be replaced. If it can be flushed, it's best to use approved flushing agents that evaporate quickly and do not leave any residue in the A/C system. The ability to flush a condenser has to be considered on a case by case basis.

The Accumulator or Receiver Drier:
Accumulators and Received Driers are not interchangeable, but they perform the same functions. This component is in the A/C system to
1) trap, remove and hold moisture
2) filter particles or debris
3) also acts as a reservoir for compressor oil and refrigerant

Typically, the accumulators are located on the LOW pressure side of the system. Receiver driers are almost always on the HIGH pressure side, usually in the liquid line that runs between the condenser and evaporator.

Accumulator or receiver drier? Here's a close up look at the difference between liquid line driers and low side (vapor) accumulators

Looking for your accumulator or drier? Here's where they are typically installed on your auto A/C system This detailed illustration will show you exactly where these components are located in a typical auto A/C system. or a detailed below is an illustration showing where the A/C accumulator and/or receiver drier would be located on a typical auto A/C system.

It's important to remember that one of the main functions of the accumulator or drier is to absorb moisture from the A/C system. Therefore they include a desiccant material. Desiccants are typically made from silica gel, and because of their affinity for water, they make great drying agents. Additionally, accumulators and driers have filter screens to trap any debris. After a compressor failure, these filter screens can easily get plugged with debris. KEEP IN MIND.. some of the components that flow refrigerant through the system work with openings of less than .050" (fifty thousandths of an inch). It takes LESS THAN 1/10 of A TEASPOON OF DEBRIS to plug these components and cause a failure.

SERVICE Required: Typically, the desiccants have been proven to become saturated after three to four years of service. Once saturated, they can no longer absorb moisture. Additionally, there is no way to check the filter screens for contamination. It is very common for the debris from the compressor failure to contaminate driers because the debris is carried throughout the system. Therefore, as a standard practice, accumulators or receiver driers should be replaced whenever you are replacing the A/C compressor. Consider that it's much the same as an oil filter on you engine. You change the oil; you change the oil filter. Like any filter, there is a 'fixed' capacity for how much debris and contamination any filter can hold. Additionally, if the accumulator or drier is not replaced, you are probably going to 'void' your compressor warranty.

Auto A/C diagnosis, repair and troubleshooting manuals - Recharge and pressure test any automotive air conditioning system on the road today! We've got all the answers!

A/C Compressor Oil:
Auto A/C compressor oil is the lifeblood of the a/c system. However, it's interesting to note that the oil in the A/C system is only there for the compressor. There are no other components that require internal lubrication; just the A/C compressor.

There are different types of A/C compressor oil ranging from PAG, Ester and mineral (now rarely used). There are also other synthetics that provide many benefits over the traditional oils. One of the best ones we've used and worked with is Polymax2. What's unique about Polymax2 is that it's compatible with all the other compressor oils, but it is no where near as hygroscopic (meaning is does not attract or hold moisture... and this is really important!) This oil is and used is  oils on the market and they t are import Up until the early 1990’s, all auto A/C Systems used a common refrigerant known

SERVICE Required: It's important to try and remove as much of the contaminated oil as possible. It's just like having a new engine installed; you don't reuse the old oil, do you? The same applies to the A/C Compressor oil. You will have to flush the A/C system to remove contamination and oil. Replace the oil using new compressor oil.

The Orifice Tube or Expansion Valve:
Like accumulators and driers, orifice tubes and expansion valves are not interchangeable, but they perform the same function in the auto A/C system. They simply 'meter' or control the flow of refrigerant.

In orifice tube systems, it's virtually mandatory that the orifice tube be removed and inspected. In most cases where the system has sustained a compressor failure, the inlet screen of the orifice tube quickly gets plugged with debris. That restricts the flow of both refrigerant and refrigerant oil.

Expansion valves are not as easy to inspect. Some designs include inlet screens as a safety precaution; others do not. There are some 'bench tests' that can be performed for expansion valves, however they are very difficult to diagnose when the system is not operating. Therefore, it's not uncommon to have a compressor replaced only to find out afterwards that the expansion valve is faulty.

Auto A/C orifice tubes work like expansion valves. TXV's have moving parts and orifice tube do not! Here's a close up schematic illustration of these valves! This illustration will provide you a better look at a typical orifice tube and expansion valve. Remember, the openings in these valves are very small. They are usually about .050" (fifty thousandths of an inch) and are quickly plugged when a compressor fails. As an example, view this orifice tube that was pulled from an actual failed compressor repair. Although the orifice tube that's pictures is extremely plugged, it only takes about 1/10th of a teaspoon of debris to block the flow of refrigerant and oil in the average auto A/C system.

SERVICE Required: Typically, orifice tubes should be replaced. Even small amounts of debris can cause restrictions in the proper flow or refrigerant. Expansion valves may have to be replaced. If they are restricted, there is no repair. If they have no visible signs of contamination or restriction, they may be tried and tested with the replacement compressor.

A/C Hose assemblies:
Whenever replacing your Auto A/C Compressor, pay close attention to all the hose assemblies. Understand that there are three different hose assemblies on each vehicle. They are; 1) from the A/C compressor to the condenser; 2)from the condenser to the evaporator inlet; 3)from the evaporator outlet back to the A/C Compressor.

Hose assemblies can be coated internally with oil and contaminants. Each hose should be dismantles and removed, then flushed as an individual component to remove all oil and debris that may be in them. Play special attention to the low side suction hose (from the Evaporator to the A/C Compressor). Depending on the vehicle and compressor design, it is possible that when a compressor  seizes and 'scatters', debris can be released 'backwards' into the suction hose. Leaving that debris in the hose (and not flushing it) will cause it to contaminate your new compressor.

Be sure that all hose assemblies are cleaned internally prior to installing your replacement A/C compressor.

SERVICE Required: Remove all A/C hoses from the vehicle and flush each one. Remember to flush in both directions until flush solvents exiting the component are clean.

Have a look at the A/C Hose assemblies on a typical auto A/C system This illustration details the three different A/C hose assemblies (or lines) on a typical auto A/C system. Remember that each one of these hoses will have to be flushed before replacing your auto A/C Compressor. Flushing will remove any debris that may have been scattered throughout the system.

Flushing and cleaning the auto A/C system:
It is virtually impossible to replace an A/C compressor without flushing the system. The extent of flushing or cleaning is dependent on the amount of contamination and debris left in the system after the failure.

As an absolute minimum, the high side of the system should be flushed. That would include the hose from the compressor to the condenser, the condenser, and the hose from the condenser to the evaporator inlet. (Note: depending on the condenser design and the amount of debris, the condenser may have to be replaced). Receive driers or accumulators can NOT be flushed (by virtue of their design). Additionally, never attempt to flush a compressor.

Flushing is really cleaning the internal components of the A/C system. It's important to use an approved A/C flush that will not leave any residue in the system and will evaporate quickly. Use caution when selecting your flushing compound. Many A/C Flushes on the market use reclaimed solvents and chemicals that are not safe for the A/C system. Flushing can be accomplished with either an aerosol type flush (which does not require a flush gun) or a liquid pour type that is used with a flush gun.

Either type (aerosol or liquid) flush agent will work, however you must have access to 'dry' compressed air or nitrogen to 'push' the flush solvent through the system. Nitrogen is the preferred method because it is an inert gas and will not introduce any moisture into the system. After flushing, it is strongly recommended that an in-line filter be installed in order to catch any debris that may be left in the system.

Using pressure (air or nitrogen) behind the flush solvent will push it through the components (hoses, condenser, etc.) to remove both oil and debris. It's important to repeat the flush process several times, in both directions, until the flush solvent removed from the component is clear. Complete details on Flushing the Auto A/C System are available here.

SERVICE Required: Flush the A/C system by disconnecting each component and flushing it as an individual item. Flush in both directions using only approved A/C system flushed.

In-Line Filters:
They're really almost like insurance for your replacement A/C compressor!
By now it should be pretty clear that any A/C compressor failure is cause for a complete system clean up. That's fine, but you should also consider additional 'insurance' for your replacement compressor.

In-line filters are typically installed in the liquid line (after the condenser; before the evaporator). The best feature of in-line filters is that they have a much larger filter surface area to catch and hold any debris while still allowing refrigerant and oil to flow. This is important because in countless cases, even after flushing a system several times, some debris remains in the system (Usually in the A/C condenser because of the long tube lengths and turns.) They are simple to install and don't require any special tools! See the A/C In-Line Filter installation instructions for yourself!

In-line filters are like insurance for your A/C compressor! Don't be fooled by those cheap filters that don't let you change the filter pack! This is the last filter you will ever install!

SERVICE Required: It is good practice to add an in-line filter to your A/C system whenever replacing the compressor. It provides the added insurance against any debris or contamination left in the system restriction flow and causing another compressor failure.

No matter what the reason is for replacing your auto A/C compressor, remember that there is a lot of other related work that has to be completed before you install the replacement compressor. We hope that this information has been helpful and we welcome your comments.

An Illustration showing a typical Auto A/C System

Schematic illustration of the typical automotive air conditioning system. We make auto A/C diagnosis and repair easy!

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