DIY Air Conditioning
Introduction

Does your air conditioning blow hot air?

This procedure will help you replace your A/C components so you can be cool in the summer!

ac.diagram

Here is the layout of the system. The A/C system is pretty simple.

The compressor compresses the freon to 250 psi of hot gas. The freon gas then goes to the condensor where it cools and tuns back into a liquid, but keeps its high pressure. It then goes to the receiver/drier which acts like a capacitor for the system. The freon liquid finally goes to the evaporator where the liquid enters the expansion valve and suddenly drops from 250 psi to 30 psi and instantly turns back into a gas. This massive pressure drop causes a super-cooling effect and turns the evaporator cold. The hot cabin air then goes through the evaporator and enters the cabin to cool your car! Finally, the low pressure gas goes back to the compressor to repeat the cycle.

Most problems with the A/C are caused by leaks. Since most A/C stuff wears out together, it's easiest and best to just replace all of the hoses and most components at the same time. This DIY procedure will walk you through the steps needed to repair your A/C system.

DIY Air Conditioning
Step 1

The first thing to do is to buy the required parts. You will need new o-rings at a minimum.

A rebuilt compressor can be found at an online saab parts store or on ebay. Buyer beware on these. My rebuilt compressor failed right away because the rebuild was not done to specs. I ended up buying a new compressor in addition to buying the rebuild!
I bought most of the components from eeuroparts.com and from the saab site. Eeuroparts does not sell the solid a/c line that goes from the receiver/drier to the condensor, but this line is the first one that breaks when trying to replace the o-rings!

The O-rings can be a little confusing when you buy them from eeuroparts, so here is a breakdown of what part numbers go where. Some of the hoses come with o-rings already installed, while others do not. The same thing is true for the rebuilt compressor. Before buying all of the o-rings you should see which ones you really need after buying the hoses.

Do not settle for regular rubber o-rings. The AC ones are made to withstand the freon gas and oil. Regular rubber ones will deteriorate quickly and cause lots of leaks!

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The hoses are straightforward, there are three to buy.

Part #: 9482365 is the main hose that connects to the compressor and has two ends on it. One end goes to the evaporator and the other end goes to the condensor.

Part #: 9482035 is the hard line hose which goes to the receiver/drier to the condensor.

Part #: 9482027 is the hose which goes from the evaporator to the receiver/drier.

I also decided to replace the expansion valve and receiver/drier as they were cheap.

I chose not to replace the evaporator since the seals can be replaced and it is the most expensive part of the system.

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DIY Air Conditioning
Step 2

First you want to empty the system of all the gas. The proper way to accomplish this is to take it to a professional a/c shop and they remove the gas and store it in a container. However, most people just exhaust the gas to the atmosphere. For R12 cars this is very bad for the environment (hence the cease of production), but R134a is not so bad.

The valve is the same type as a tire valve, you just press it in and the air comes out. If you have the special tool you can remove the valve completely so you don't have to sit there holding it in.

Once the gas is out you can start removing hoses. I started with the compressor hose. You take a 15"mm socket and remove the bolt holding the hose to the compressor. Once this is removed you will find the first two seals that tend to leak.

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Follow the short hose to the evaporator and remove that connection. For this you will need either a 1-1/16" wrench or a good adjustable wrench to hold the evaporator still while you disconnect the host. I believe the hose connection is 7/8".

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Now follow the bigger hose to the condensor. In order to disconnect this one, you first need to disconnect the bottom hose which goes to the receiver/drier. These connections will benefit the most by spraying them down with degreaser and penetrating fluid. I ended up breaking the hard line hose while removing it.
You will need your 1-1/16" wrench again to hold the condensor still while a 3/4" will work for the lower connection and a 7/8" will work for the top connection.

I did have a small problem getting the top hose out of the condensor. It was corroded pretty good. I finally got it off by cutting the hose to make it shorter and then while using the wrench to hold the condensor still, Royce was twisting it back and forth. It did take about 1/2 hour of fighting to get it off!

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Now remove the final two hoses. The space is tight by the receiver/drier, but a wrench will fit in there.

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DIY Air Conditioning
Step 3

Now it's time to remove the compressor. This is very straight forward.
First you need to remove the belt by loosening the two 13mm bolts holding the a/c idler pulley onto the block. Then loosen the adjustment nut until the belt slips off.

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Time to remove the A/C compressor! If you can reach the lower 12mm bolt under the alternator, you can just remove the entire A/C bracket with the compressor attached.
The bottom 12mm bolt does not need to be removed. Just loosen it. The bracket has a slot rather than a hole for the lower bolt.

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The final piece to remove is the expansion valve. You need to remove the 4 torx screws holding the evaporator cover on.
Slide it off and you will see the expansion valve. There are 2 copper lines that need to freed up and then the valve can be unscrewed.

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Now it's definitly beer break time

DIY Air Conditioning
Step 4

Replacing the condensor is next on the list. The first thing to do is to remove the grill and front bumper.

The bumper bolts can be a real PITA if they have never been removed before. The best tool to get is a good hex socket. You can easily break a regular hex key trying to loosen the rusted bolts. Now remove the small bolts that attach the bumper extensions to the bumper.

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Before pulling the bumper off you might have to disconnect your fog lights. I don't have them so I don't really know!
The bumper should just pull off. You can do this yourself as the bumper only weighs 20 pounds or so.

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Note: The hoses that go across the radiator are for my water/air intercooler...

Before you can remove the condensor you need to remove a rubber piece that covers the bottom of the condensor.

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Removing the condensor is very easy now. Unscrew the 4 screws and it will drop right out from the bottom.

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Now just slide the new condensor back into place and bolt everything back together. Before putting the bumper back on be sure to tighten up the hose connections. It is much easier to do when the bumper is off!

DIY Air Conditioning
Step 5

Now to put everything back together. You want to try and keep dirt off of the o-rings. Even very small pieces of dirt can clog the expansion valve.

The first thing to do is to swap compressors and then remount the new compressor onto the engine.

Now install the new expansion valve. Be sure to use o-rings on the fittings or else freon will leak through this.

Put the cover back on the evaporator and then you can connect the compressor hoses.

Now install the new receiver/drier and connect the hoses to it.

The final step is filling the system with gas. You can do this yourself if you have some special tools. The required tools are the R134 gauges and a vacuum pump.

The gauges can be bought for $50 online or from a car parts store. The vacuum pump is expensive, so try to borrow it.

Hook up the vacuum pump to either side and let it run for at least 10-15 minutes. After this you can do a preliminary check for leaks by closing the system in a vacuum state and watch the gauges. If you lose your vacuum then you have a leak somewhere!

Filling the system requires knowing about how much freon you need and reading the gauges to determine the pressure in the system. From what I've seen the low pressure system should be around 30 psi and the high pressure should be around 250 psi.

You also need to add some oil into the system. If you don't your A/C compressor could sieze!
Some new A/C compressors come oiled by the factory and others do not. Just follow the recommendations in the box.

If you are using an old compressor, then you need to add oil for sure as the vacuum pump would have sucked everything out.

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