Should I attempt to replace my a/c compessor myself?

I was told last week by an auto mechanic, who I asked to tighten the belts on my engine, that it was the a/c compressor clutch that was freezing up and squealing, not the belts themselves. He provided an estimate of $450 to do the work for me. This is much more than I can afford. I’ve worked for years as a do-it-yourself car mechanic, but am feeling unsure about tackling the a/c system. I have a couple questions:

1.) Is it a bad idea for amateur mechanics like me to attempt to replace components in the a/c system? (e.g. too complicated, dangerous, etc)

2.) Would it be possible to simply replace the a/c clutch?

This is a 93 Dodge Shadow 2.2L with 218K miles. The compressor is an original part and has never been replaced. It works fine, except for the clutch apparently freezing up in hot weather after the car has been driven, turned off, and turned back on while the engine is still hot.

A/C is no longer a DIY. Not only do you need expensive equipment, you need a license to buy the materials. The law changed to protect you and the inviroment.

My car uses the new a/c system coolant - it was converted 5 years ago and has been doing great ever since. The system is not leaking at all, so it is full. Does that change anything?

No. It is illegal to dump the refrigerant to the atmosphere. The system must be purged before you disconnect any tubing. Get 3 quotes for the work and take the one that you like best.

If it is really just the clutch, I think that it can be replaced without replacing the entire compressor. I had the same problem on my 1978 Oldsmobile some years back. One shop wanted to change the entire compressor. I found a shop that said it only needed a clutch on the compressor. If the clutch on your car can be separated from the compressor and it is really the clutch, I would just replace the clutch. It is easy to tell. Pull the connector off the clutch when it starts freezing. If the clutch turns freely, the problem is the compressor. If it doesn’t turn freely, the problem is the clutch.

Thank you everyone for your replies. It helps me to make an informed, wise decision. Once I get this resolved, I will post back here with how it went.
Best regards,

Sure you can replace the clutch, but you are going to buy a special puller.

If the problem is only the clutch then that can be replaced without discharging the refrigerant. Sometimes access can be a bit of a pain though.
If need be, the compressor can be unbolted from its mount without disconnecting the refrigerant lines and moved around a bit for better access.

There are a few special tools needed, including a pair or two of snap ring pliers, but these tools should be available from AutoZone, O’Reillys, etc. as part of their free tool loaner program.
Just place a deposit on the tools and get it back when you return the tools.

You don’t need to replace the entire compressor, meaning that you DON’T have to discharge the refrigerant and it is perfectly feasable and legal for you to attempt this. Don’t pay $450 for it if you think that you can do it yourself and do it right. If you’ve got lots of experience with cars then this will be not much more than JUST another component replacement.


Just replace the clutch.
Yes you will need special tools. As ok said, they’re probably available as loaners.
Good luck!

-Matt (again)

I spoke with a local mechanic my family has used for years and he said that the problem could be the clutch, but it also could be the compressor - in that there could be a problem with the compressor that makes it so hard to turn that the clutch freezes when it is engaged. The problem has grown noticeably worse in the last 2 weeks. I am going to attempt to buy a used a/c compressor and have him install it for me (I created a new post about this today under the title “used vs new parts”).

Before visiting your other post, make sure the radiator cooling fans are coming on with the compressor.
If the fans do not work the high side pressure will climb and this can cause a belt squeal.

I can’t see that it would be the clutch. If the clutch wasn’t working, it would just free wheel unless it were locked up and then it would run the compressor continuously. Sounds more like the compressor itself is locked up and when the clutch is energized, causes the belt to squeal.

In order to do it yourself, you would need to have someone evacuate the system, then bring it home and put the compressor on, drive it down again dry, have the system cleaned and the dryer replaced, and then recharged. So all you really save is the labor to put the compressor on which is not that much, plus all the hassle involved and if there is a problem, who do you blame. Bite the bullet.

The fan does come on when the compressor is engaged. As a matter of fact, that is the only time the fan comes on, which has always seemed weird to me, but the car runs fine so I haven’t messed with it.

ugh. Yes, I’ve thought of that and your advise is wise. Thanks.

If you can tackle the compressor replacement yourself, then you will save a bunch of money there.

Also, there is absolutely no reason that you can not replace the receiver dryer yourself. The expansion valve (or H valve, this is a chrysler system) should be replace while you’re at it too. All O-rings and seals on any fittings you disconnect should be replaced. And if you feel abitious and prudent, you can replace O-rings and seals on fittings that you WOULDN’T have disconnected.

Then all you pay to have done are the evacuations, which won’t be too expensive. The cost of the components will be around 300 dollars if you buy a new compressor, somewhat lower for a used. If you plan on keeping this vehicle in regular service for any substantial length of time, then go with a new compressor, not a used one. Use only a new receiver/dryer and expansion/H valve.

You might want to have the system professionally charged too, but there’s no reason you can’t do this yourself if you want to.

Once the system has been initially discharged, there’s very little “danger” involved with A/C repair. If you like to learn new things then perhaps this is your chance.


Thanks Matt. I’ve decided to first try a new clutch on the compressor. I want to evaluate every possibility, starting from the least expensive on up. The only trouble is that my repair manual does not cover replacing the clutch - only the entire compressor. With my dad’s help, I think we can get it done, but I would feel better having the instructions in front of me to list out any gotchas beforehand. Any advice there?

There is a website called All Data DIY.

It’s basically a gigantic online repair manual. It costs $25 dollars for a year’s access for one car, but it has every single little bit of information on your car, and every car. AllData will have the clutch replacement proceedure.

If you really are looking for the simplest and least expensive possibility, I’d suggest that you go out to an autoparts store and buy a two dollar can of Prestone belt dressing. I would never reccomend this as any kind of solution to a problem, but if after applying the belt dressing, the squeaking sounds stop, you may have no need to replace the clutch at all. I find it odd that your mechanic was “tightening” the belts. Many modern cars use automatic belt tensioners which are spring loaded.

If it still squeaks and squeals, then try turning the A/C off. Does the squeal continue with the A/C switched off? If it does, then you might very well dodge a bullet on this and not need to replace the compressor clutch.

If the squeal continues, take the car to an A/C service shop and have them test the A/C system pressures. An excessively high high-side pressure can cause a belt squeak due to the additional, massive effort that must be exerted on the pulley by the belt to overcome the extra pressure. If this is the case, you will again dodge the need for compressor clutch replacement. And instead, you may simply have a clogged condensor, a bad fan, or a system that has too much refrigerant in it. Or it could end up being something more serious, such as a restriction in the system that requires discharge and flushing to fix.

So before you go and replace the clutch, which is indeed simpler than replacing the entire compressor, go through these fairly simple and painless tests to verify that you’re not wasing your time and money on a fix that won’t do.

And remember, even if none of those tests take your focus off the compressor clutch, the problem may lie in another pulley or component, or bracket, or even a bad belt tensioner. I’d reccomend replacing the belt FIRST (since it’s relatively inexpensive) regardless of how old it is.


Wow, now that was a lot of helpful advice! Thanks so much for taking the time to type all that! The belt is at least 5 years old, but no mechanic has ever said it needed replacing and when I look at it, it appears fine. Still, those simple tests you mention are very much worth looking into and I will be doing that tomorrow. Best regards.

FYI: The repair manual stated that only the V-6 models with serpentine belts have automatic belt tensioners.