*Queue corny 1950s instructional video music* Hello consumer, are you finding yourself sticking to your leather seats like an egg on a cast iron pan? Are your tired of wondering where the luxury went in your BMW, Mercedes, Audi, Saab, Volvo, or other European car? Have you ever packed extra clothes on short trips, assuming you will sweat through your current garments? If you, like millions of others, have an automobile equipped with air conditioning that just isn’t pulling its weight, then you’ve landed in the right place. *Needlescratch*. Judging by recent AC Parts sales, many of you are working on the air conditioning system of your European car lately. The air conditioning system is a complicated one, and successfully diagnosing bad AC parts can be an ongoing struggle without a good foundation in how they work. Consider this your A/C 101 basics course, hopefully after reading this you will be able to get your AC parts back in tip top shape. This is split up into two parts: Part One describes the components and Part Two describes
A/C Parts Basics: Part one, what’s in there anyway?
There are several components that are vital to the proper operation, all available at eEuroparts.com. They include, in order of travel:
The A/C Compressor
The A/C Condenser
The A/C Receiver Drier (Accumulator)
The A/C Expansion Valve (or Orifice Tube in some systems)
The A/C Evaporator
Before getting started, real quick, I want to stress how sensitive all of these AC parts are to moisture and contaminates. The interior of the AC System will only work its best if it is completely clean and perfect. This is why we recommend a full flush and fill be done by an experienced shop with the proper equipment after replacing any AC parts. It’s also why we recommend replacing the AC condenser when you have the opportunity if you are working on other parts, because it can act like a filter and become clogged over time, resulting in reduced performance out of your freshly maintained air conditioning system. Anyway, on to the parts, in order of flow, starting with the compressor.
A/C Compressor – Shop for your vehicle
The compressor does the heavy lifting in all A/C systems, and is powered by the engine by means of belt and pulley. The main purpose of the compressor is exactly what it sounds like, it takes the cold refrigerant vapor coming out of the evaporator and compresses it into a hot high pressure gas. The A/C Compressor is probably the most complicated single component in the air conditioning system of your car, and can fail in many ways. You used to be able to replace A/C Compressor seals, A/C Compressor Clutches, A/C Compressor bearings and other items, but the industry (of course) is moving in a direction that prohibits maintenance and rather forces customers to buy a complete new assembly. Signs of a compressor that needs to be replaced can be leaks of any kind (bad seals), bad or seized clutches, terrible groaning or grinding noises (internal bearings), or excess drag on the engine by any combination of those three. A bad AC Compressor should not be left alone since it can cause unnecessary drag and fatigue on other engine systems connected to your serpentine belt, and contribute to an inefficient car.
*Top tip – Try to make sure you use your AC a few times a month, even if you are not driving the car in the winter or even have functioning AC. This will make sure the compressor seals and associated components stay lubricated and won’t dry out.
A/C Condenser – Shop for your vehicle
From the compressor, hot high pressure gas flows to the condenser, which is the large aluminum radiator on the front of your car with metal pipes going to it. Functioning as the first of two heat exchangers in your air conditioning system, the A/C Condenser receives the hot high pressure gas and cools it down with fresh air from outside the car. For the condenser to function you must always have airflow, which is why it has a dedicated cooling fan attached to it for when the car is stationary. The hot gas is cooled down enough for it to condense into a liquid (get it?) and travels onto the next stage in the system. A/C condensers are extremely delicate because their cooling effectiveness must be so high. Because of this, they are prone to taking damage from road debris or careless mechanics.
*Top tip – The passageway are extremely narrow, almost needle thin on many newer cars, which means they can get clogged easily. Sometimes full A/C flushes will not be able to remove contaminates from condenser, which is why I recommend replacing the condenser at the same time as the compressor and A/C Receiver Drier for a complete AC service (the expansion valve is a good idea too, if you can reach it easily). You want to avoid turning your A/C condenser into an expensive filter.
A/C Receiver Drier (Accumulator) – Shop for your vehicle
After the cooled down compressed liquid leaves the condenser, it will go into the receiver drier, also sometimes known as the accumulator. Many times this is directly adjacent to the condenser, or even attached, and appears as a reservoir which accumulates the refrigerant. A key part of this component is a filter/desiccant that will remove the moisture out of the refrigerant and oil. After awhile, this part will fill with water (capacity is usually really only a few drops), and additional water vapor that seeps into the system will remain there and corrode every single component to the point of non-function.
*Top tip – Every single time you change out one of the AC Parts in your car, you should change the A/C Receiver Drier. You have the system depressurized anyway, and chances are it will be awhile until the next time you do if everything is done right.
A/C Expansion Valve (or Orifice Tube in some systems)
These AC Parts are positioned right in front of the A/C Evaporator, and are the key point in the process where the refrigerant takes a turn for the colder. If you remember your physics class in school, compression always results in heat, and expansion results in cooling effect. Where the compressor cranked up the pressure and heat, and the condenser turned it into a nice dense liquid, the A/C Expansion valve can now funnel that liquid through a tiny hole, and into a larger opening on the back. The expansion process allows the refrigerant to expand and cool into a semi vaporous liquid, which then enters the A/C Evaporator. The expansion valve can become stuck or clogged, and the the orifice tube can also easily be clogged since the passageway inside it is so narrow to get the maximum expansion effect. If you are replacing your Evaporator, it’s a good idea to also replace your expansion valve, or at least have a good look at it. Some evaporators come with valves built in, check them out on eEuroparts.com.
Differences between the expansion valve and orifice tube: When you see an evaporator with the input and output pipe that join together at a junction, that’s the expansion valve. It is measuring the temperature of the output, and then adjusting the input valve to regulate the most efficient flow. In systems where the input and output pipes can’t be near each other, an orifice tube is used to start the expansion process. Systems with an orifice tube regulate the flow with other means, usually via valves and clutches in the compressor.
A/C Evaporator – Shop for your vehicle
Now that the vapor/liquid refrigerant is able to get some elbow room to expand, it continues the process on through the evaporator. The cooling effect is pretty dramatic in the evaporator, which becomes very cold. The blower motor then circulates air through this freezing cold aluminum radiator and there you have it; a comfortable environment inside your vehicle on a hot day. The key failure areas of the evaporator are leaks, which are relatively uncommon. In most cars you have to open up your dash to get to this component. From the A/C Evaporator, the low pressure cool gas now goes back to the compressor to do it all again.
*Top tip – If you have a moldy smell to your A/C, there’s a good chance the box with the evaporator in it has mildew. When the evaporator core cools down, water collects on the outside and it eventually drips down and out of the bottom of the car in the form of condensation. The dark, damp ducting surround this is prone to harboring mold, and you will have to go in and clean it if you really want to get rid of the smell.
Refrigerant and Oil – Shop for your vehicle
A hugely overlooked part of the perfectly functioning AC system is the refrigerant and oil, most specifically the oil. The refrigerant is a chemical that by nature takes very well to converting from a gas to a liquid and back to a gas easily and within a narrow temperature range, as well as good density as a liquid and not be super dangerous/corrosive. The shallower the temperature range that this can occur in, the smaller the radiators and compressors can be, making for more efficient, cheaper systems. R12A was the standard for awhile since it fit this bill perfectly, only problem was it was about as toxic and ozone depleting as you can get. Systems were converted to use R134a, the current standard, and now a new style of refrigerant called R1234YF has been filling new car A/C systems. To see what your car has, and the quantity, Nissens has put together a great lookup guide HERE.
Whenever A/C work is done, the proper amount of oil must be added to ensure the work takes well and stays reliable. When the oil gets old, burned, or has too much flush or dye in it, it will not lubricate properly and it will ultimately destroy your compressor and lead to other issues with your system.
A/C Pipes or A/C Lines and seals – Shop for your vehicle
Although usually not much of a problem, A/C pipes are the final piece of the equation for the AC system in your European vehicle. After the compressor they are very high pressure, and both sides contain shraeder valves for fill, drain, and testing purposes. A/C pipes can corrode through if you haven’t been caring properly for your car, and will ultimately need to be replaced in this situation. Each end also includes a seal, which can degrade and cause leaks. Always remember to get new o-rings if it doesn’t already come with them.
AC Parts Basics: Part two, what do I need to buy?
Because of the complexity of the system, self diagnosing problems with the A/C system can be difficult. We recommend having a professional diagnose your car, but before you take it to the shop there are a few things you can do.
If you have NO air conditioning, and it did work at some point, pick up a can of refrigerant at your local store and dump it in. We don’t recommend ever doing this as a serious service, but for diagnostic issues it will at least let you know if you have a leak somewhere (by far the most common cause of AC issues).
If your A/C starts cooling down, then a day or two later its back to the way it was, most likely you have a leak to find. Check the pipes, compressor, and especially the condenser for damage. We sell a type of PAO oil that has dye in it to help find leaks, but if this sounds over your head and frustrating, it’s best to have a shop diagnose your system.
If it stays cool for awhile, long enough to deduce that the system is still sealed, then you can start making a laundry list. If you are looking to get your aging car’s air conditioner back to ice cold, the very best plan of attack would be to replace the condenser to get rid of clogs, the AC drier to get rid of all the water, and the compressor if you can, since mechanically it takes a lot of abuse. We offer both refurbished and brand new AC compressors to help with your price point.
After doing any service where the system is opened, it is extremely important to have a professional flush and fill, where a complicated machine is hooked up to your AC system and circulate fresh oil and refrigerant, help remove blockages, and add the perfect amount of refrigerant and oil, at the right temperature and pressure. It is very hard to do this in your garage without getting contaminates into your system that will reduce the life of your work.
Go to eEuroparts.com and put your vehicle in the selector at the top. We have an AC parts category that will send you directly to what you need!
We carry a variety quality name brands (in addition to Genuine OEM), many of which are OEM, that you can trust will last as long as the original part.
Behr – A German company that has been around for over 100 years, Behr delivers OE quality compressors, expansion valves evaporators, and condensers at a great price point
Nissens – Based out of Denmark, Nissens is OEM on several high end car manufacturers, including Bentley, Aston, and even Lamborghini. For you, that means there is no compromise on quality, and often times Nissens aftermarket parts are re engineered to address problems with the original designs, such as uprated valves and seals for longer service life.
Four Seasons – Four Seasons is the world’s largest re-manufacturer of compressors, as well as other climate control products. Four seasons compressors are an excellent choice if you are on a budget but are still interested in a long service interval.
Santech – Specializing in common service items such as seals and shrader valves for service ports, Santech provides important and often overlooked parts that will keep your AC system running strong.
ACM – As an OEM for several manufacturers, ACM specializes in A/C Condensers, receiver driers, as well as evaporator cores and expansion valves. These are highly recommended AC parts if you are servicing your high quality European vehicle.
Rein – Rein manufacturers high quality AC hoses, expansion valves, receiver driers, evaporators, and seals for a very good value. We have a huge supply of these, so if you are replacing AC parts and have a hose that looks suspect, Rein makes it possible to add on some AC lines without your wallet taking much of an additional hit. Our Rein availability is fantastic, so if you need something chances are we can supply it!
Generally you can expect doing your first major AC service between 100 and 150k miles. With good care, you hopefully won’t have to open it up again!