Finding the correct part is often one of the hardest things to do. This is especially true if you have something big like a semi truck or some Catepillar farm equipment. Finding the correct Sanden Compressor can be very challenging.

We have done numerous write ups on finding the correct compressor. In this case you need to find the type of compressor and the number on it. Many of the big Peterbuild, Volvo or other large trucks use a Sanden SD7H15 Compressor.

If you have an international, Caterpillar or other piece of farm equipment you’ll need the same info. These often used a Sanden SD7H15HD Compressor or a Flx compressor. The HD is for heavy duty. Many of them have dust covers for working in the fields or constrution sites.

For any of these you will need a Sanden Compressor list to find your part. I’ve got some good links in this article or you can look around.

So I’ve had some people ask how does the ac compressor system breaks down. Below are a couple of useful charts and diagrams that will probably explain it better than I can.

The air conditioning compressor turns liquid freon into gas freon. The condenser cools the gas down into a liquid, sending it to the evaporator. The evaporator turns cool liquid into cool air, removing the heat from the cabin. The warm liquid goes back to the compressor. Then it starts all over again

Some keys to the system are that the size of the fins on the ac condenser directly affect how well it performs. If those fins are not working very well then the gas will never get very cold and performance will suffer. We have done lots of articles about condensers, so feel free to do a search and find those.

Check out the diagrams for more info.

So I’ve gotten a few questions regarding the AC Compressor System Expansion Valve and how to repair it.

All ac systems have to have a place to release excess pressure. Many air conditioning compressor systems use an expansion device to release pressure in the atmosphere. This can either be an expansion valve or an expansion block, see picture for more on the difference. They are just different designs of the same. The valve has an external sensor arm while the block is pressure based.

So how to you repair an expansion valve? The answer is to buy a new one. You can clean it out and blow some air through it, but with prices of only $30-$60 for a new one, its just not worth the risk. Most expanison valves are mounted on the ac evaporator, which is inside the firewall. Replacing it can be 3-8 hours of labor because you may have to disassemble the whole dash. Whether you are paying someone for that or doing it yourself it is just not worth it. Buy a new one from a trusted source.

One of the most frustrating things about buying auto parts is getting the wrong part. If you buy furniture or electronics and its a little too big or too small, you can still use it. In car parts, you have to be exact, especially with an auto air conditioning compressor where there is no room for mistakes. Here are some tips.

First thing to do is to look at the picture of the ac compressor and print it off. Compare that to the one in your car. If it looks exactly the same, you should be good to go. If it is close, you may want to do a little work. Get a picture of your air conditioning compressor label. Like this one below.

You should also take a picture of the compressor in the car. This will help the part supplier double check with you. By itself the picture is useless, but combined with the label and the vehicle it can be helpful. If you have any doubt about getting the correct part, you want to call the supplier and email in pictures like these two. Just not worth getting the wrong parts.

Finally you can remove it from the car and take some pictures of it. The picture below uses a digital caliper, which is a great tool for being very exact. If you do a lot of things that require measuring exact numbers, this tool is very important. Here we get the length of the ac compressor clutch from the beginning to the center of the pulley groove. This measurement is important to ensure the belt lines up with the crank.

When replacing an AC Condenser there are lots of things to consider. First, you will need to pick out what kind of condenser you need. Second, what to know during install.

You may need to change your a/c condenser if your car is not blowing cold enough, is contaminated or is damaged. The first question is what to buy. The most popular condenser types are serpentine and parallel flow condensers. See the picture for more info. Really though any type will do, and unless you are picky, all will work about the same. Keep in mind, the better performing condensers are also the hardest to clean.

For install, you will need to service the ac system including replacing the ac drier and evacuating and flushing the system. Most people don’t know that the auto air conditioning system should be serviced every 60,000 miles anyway, so this is good maintenance and will prolong the life of your ac compressor. Most often the condensor is replaced because of contamination, so cleaning out the system is important.

As I do a great deal of work with auto AC compressor, I get asked alot about what compressor brand do I recommend. Should you go OEM, aftermarket or Remanufactured. This is a complicated answer and requires some explaining.

First off, you need to know what an OEM or OE compressor is. OEM is original equipment manufacturer. Toyota does not make any air conditioning parts, never has. Neither does ANY auto manufacturer since GM spun off Delphi and Ford spun off Visteon. So if you are looking for a ‘Toyota’ compressor, you are going to get a Denso compressor in a Toyota box. So why go through Toyota when you can go to the OEM. Just like your probably don’t put on Mercedes Tires on your car, you don’t need to do the same with other auto parts

What is an aftermarket and reman then? Aftermarket is a copy of the original compressor designed for that car. Most are not universal fit, they are built for your car, so they should drop right in. The problem here is that there are lots of manufacturers on these. Some are good and many are not. Find a supplier with a solid warranty. If they don’t have an immediate replacement warranty, do not trust the quality. Discount AC Parts (1-800-398-3128) has a fantastic warranty and a good line of house brand products. Reman used to be the only option and still can be fine. The problem is that you are often inheriting someone else’s problems. If new is available, go new.

So we are down to an OEM new compressor and an Aftermarket new unit. The first question is what is the price? If the price is close, go OEM. It ensures you are getting a quality product without having to wonder. You are already probably saving lots over the dealership, so it is a good buy. If the price is far apart, then ask about the quality. What kind of warranty does it have? What will you do if there is a problem? These are important questions to ask.

We have discussed previously about the dessicant element in the air condtioning compressor system, but more questions came up. When is it used and how and when do you change it?

So the first question is when do vehicles have it. Starting in the late 1990’s Toyota a/c compressor began using the dessicant element instead of the drier. Most manufacturers like Honda began using it shortly after, while some like the Isuzu AC Compressor never used it. It really depends on the vehicle and if you look at a AC Catalog like discountacparts.com you will be able to find out what your vehicle has.

The other part is how do you change it. Most cannisters use a 10mm hex nut on top. You pop off the top and change it over. Usually you should flush before you change the ac drier, but since the flush could cause the bag to tear or rip, I recommend removing the dessicant, then flushing. Once it is clean you can add the new bag in.

Definately a scary sound when the car makes unusual noises. Car noises can make anyone feel nervous. Brakes squeal can be dangerous and engine knocking can be very bad. Another bad noise is when you get a whining or grinding noise when you turn on the Car Air Conditioning.

There are a number of reasons that you can get noise. If the noise only starts when you turn on the Climate Control and your vehicle A/C is clutch driven, then the bearings in the clutch have gone bad. You can try and replace the clutch, but most likely have to get a new AC Compressor and it will have to be changed. If the system does not have a clutch, then the compressor will definately need to be changed.

If the noise is constant then more research needs to be done. You need to be very sure it is coming from the ac compressor. If it is a always on system like some late model Denso Compressor then the compressor will need to be replaced and the system serviced.

The key thing to be checking in the case of compressor noise is head pressure. If a compressor builds up too much pressure the heat will cause the clutch to melt and the bearings to warp. This will cause lots of problems and make for a noisy system. Do not put on a replacement reman ac compressor without determining the cause of this head pressure. Usually it is a blockage in the system, problably at the condenser and it should be replaced as well.

I am constantly amazed at how people assume an ac compressor is an easy fix. Take a look at the pictures.

This is from a 96-00 Honda Civic AC Compressor This is a scroll design ac compressor. All a/c compressors do the same thing, but many use different designs. You can see the scroll design in the second picture. The 2 scrolls roll around each other at high speeds to heat the refrigerant.

The side of the compressor on this one was actually blown out. The relief valve looked clogged. My best guess at failure is that too much pressure in the air conditioining system built up and the pressure backed up at the compressor. The system was probably blocked at the ac condenser and the pressure never made it to the expansion valve. The relief valve gets clogged and there is no where for the pressure to go. At 300+ pounds of pressure, you can blow out a side wall.

Moral of the story is to do the job properly and make sure the system is clean before starting.

What the hell is the AC Compressor dessicant element? This is a good question.

Older vehicles used to use a metal drier as the filter in the A/C System. Starting in the late 1990’s, the Toyota AC Compressor began using dessicant elements instead. They recognized that servicing the A/C System required changing this out. These dessicant elements are much easier to replace. Most condensers have a cannister on the side of them, see picture. You open the top of the cannister with a 10mm hex nut and change out the dessicant. If the old one is black then you’ll need to change the whole condenser.

As you can see in the picture, the dessicant looks like a long tea bag. It is the same thing you find in your shoes, just a finer grain. The dessicant pulls moisture and debris out of the refrigerant. While refrigerant is a liquid, water in the system can be a big problem.