complete AC overhaul-what steps to take?

[ManySHOs]

Hi everyone
I have an engine swap coming up soon (when the weather gets cooler, so maybe Sept-October). I was considering going to r134a because I currently run r12. My r12 works but it blows cold only about 70% of the time. From the way the AC clutch keeps cycling on and off, I imagine that it's low on r12. I'd prefer to keep the r12 but some of my AC lines are really rusty and I figure that this won't last forever. I was thinking of having the system professionally evac'ed a day before the swap. During the swap, I'd replace the hardlines (do I need to swap the compressor out too since it ran r12 or can it just be cleaned-if it's cleaned is that something a shop would do during the evac or do I do it?). Once I've completed all of the mechanical work, I'd have the system filled with r134a.

I need to double check the Helms but I wanted to ask here too; what exactly would I be replacing if I did this? I'd like to get as much new stuff as possible. Some people have mentioned www.ackits.com as a good place to get some of the stuff. I'm just a n00b when it comes to AC stuff though. If you guys can recommend any vendors, steps, parts, expected prices to pay, good procedures, etc. I'd really appreciate it.

Thanks!
Ian

 

[Trusty89]

I've been searching the archives ALOT on this subject, very helpful. Hopefully someone more knowlegable will post but since noone else has yet, here's what I gathered from my search...

1. Replacing the hardlines while the engine is out is a VERY good idea.
2. Don't bother cleaning the compressor just get it evac'd and do a system pressure test. Make sure the compressor turns smoothly and takes no more than x lb ft (do a search for spec) and make sure you put not just R134 in but the oil as well.
3. You should change the accumulator and drier as well. You can convert without, but the system probably won't last as long because of the R12 remnants.

 

[ManySHOs]

I've been searching the archives ALOT on this subject, very helpful. Hopefully someone more knowlegable will post but since noone else has yet, here's what I gathered from my search...

1. Replacing the hardlines while the engine is out is a VERY good idea.
2. Don't bother cleaning the compressor just get it evac'd and do a system pressure test. Make sure the compressor turns smoothly and takes no more than x lb ft (do a search for spec) and make sure you put not just R134 in but the oil as well.
3. You should change the accumulator and drier as well. You can convert without, but the system probably won't last as long because of the R12 remnants.

Great info, thanks-now, where are the dryer and accumulator lines located? For some reason I thought that they were part of the hardlines...They are in the engine bay right? And the hardlines bolt to the compressor and are sealed with the infamous O rings that I should replace, right?

Will it be safe to drive the car with the compressor completely dry (ie, no oil or r134a?) After I get the system evacuated I'm going to have to drive home. After I swap the engine I'm going to have to drive it to a shop to get the system filled unless I buy those little cans and do it myself...I don't want to **** the compressor. I guess it technically doesn't spin unless the clutch is engaged (AC on)?

Thanks!
Ian

 

[SHOtimer]

What you will want to do is find out if your compressor is good or not. A good AC shop will have a 'sniffer' that smells whether the gas is leaking or not, you do not want to put together a new AC system with an old worn out/leaky compressor. You can still get brand new compressors, or quality remaned ones for a little bit of $ - or even a good used one.

You will need to replace the accumulator (the accumulator and the dryer are the same thing.) You will also need to replace the orfice tube. You can get both these parts at a Kragen, autozone....or whatever.

You will want to replace all the O-rings in the system with new R134-a ones. While everything is out it would be a good idea to get the condenser chemically flushed and cleaned.

Yes, you can drive the car with the system evacuated. The compressor won't run with an empty system, their is a low pressure switch to prevent that from happening.

Doug

 

[kd7kmp]

Adding to what the others have said...get every component flushed to remove all traces of the old mineral oil--the lines, condensor, compressor, evaporator, etc. There is a common misconception that you can leave the old mineral oil in if you use a POE oil. This is not necessaryily true. The R134 and POE/PAG oils can react with the mineral oil to create acids that are very bad for the system. Replace every oring with an R134a compatible oring. Most auto parts stores sell oring kits. Replace the orifice tube while everything is apart as well as the accumulator. If there is any concern that the compessor is bad then replace it. The new unit will be r134 compatible and will be ready to bolt in. Be sure to check out http://www.ackits.com or http://www.acsource.com for any parts you need. I have used both of these places extensively and they have MUCH better parts than most local auto parts stores.

Kevin

P.S. go to http://www.acsource.net/acforum/ for an great forum.

 

[ManySHOs]

Do most people typically leave the condensor in and just have it cleaned out of all of the old oils? Thanks for the links; it helps me to look at the pictures and read what the parts are and how they work. Ackits.com has a lot of listings for the 3.2L. Are these different than the mtx SHO?

And how many O rings are there? I'm aware of the O rings on the compressor where the hard lines bolt to. Are they double stacked or just single? Are there other O rings in the system that I should replace?

Thanks for all of the advice; now that I know what I'm getting into, this seems easier than I thought before. Technically, if I replace everything (compressor, condensor, hardline, liquid line, drier, orfice tube) is there any need to even make sure everything is clean? Or are there integrated parts in the AC system that I can't replace that would still have the old oils in them?

Ian

 

[SHOtimer]

Thanks for all of the advice; now that I know what I'm getting into, this seems easier than I thought before. Technically, if I replace everything (compressor, condensor, hardline, liquid line, drier, orfice tube) is there any need to even make sure everything is clean? Or are there integrated parts in the AC system that I can't replace that would still have the old oils in them?

Ian

The only piece you won't be able to remove is the evaporator in the dash, which shouldn't really be a problem. Also, the manifold lines (the ones that bolt to the compressor, and a couple hard metal lines are all going to be fine to reuse.

Yes, the AC system's are different between the 3.0 and the 3.2, but the compressors are the same.

Doug

 

[kd7kmp]

The condensor can be left in place to flush it if you are doing the work yourself. If you are paying someone else to do it take it out of the car. If you do clean it yourself back-flush it. This will help dislodge any small debris that may be in the system. If you have had a compressor failure or see any discoloration or debris in the lines when you take them off then just replace the condensor--especially if you have had "black death".

Orings will be present at any point where the lines are bolted together. I don't know how many there are. Around here Autozone sells oring kits. It should contain any oring you will need. The replacement orings are usually green or blue. Although AC Source has vehicle specific kits. You will have to put r134 fitting over your r12 fittings as well.

Any part you replace will come to you sealed and ready to be installed. You wouldn't have to clean those parts. But any part you don't replace will need to be flushed to remove all the old oil. Most new and rebuilt compressors come with some oil in them. The label will tell you how much is in there and what type of oil. It's important to make certain you use the same oil type and viscosity that is in the compressor.

After you have everything together you need to pressurize the system with an inert gas like nitrogen or CO2 to check for leaks. Some people think this is not necessary and instead draw a vacuum to check for leaks. I have had many cars not leak under vacuum only to pop an oring after the system is charged. That is a big waste of refrigerant and not good for the environment. If you don't have the equipment to test for leaks and charge the system take it to a shop or friend that does have the proper experience and equipment. Skimping at the last few steps can cause poor performance or system failure.

I hope this answered you questions.

Kevin

 

[rangerj]

Some added thoughts:

Remove the condenser and have a radiator or A/C shop pressure test it. If it is OK have them clean it, or you clean it.

If you are going to reuse your compressor DO NOT clean it out with anything. Simply drain it of the R-12 oil. You test the compressor for smoothness by turning it clockwise. Then turn it with a torque wrench. It should not take any more than 84 inch pounds of turning torque to turn it. This is done to a compressor that has been removed from the car, and NOT one that is mounted and under pressure.

If you are going to use a new or rebuilt compressor you need to read and understand the warranty conditions. Most will require that you get new Accumulator/dryer and oriface lines, AND have the rest of the system flushed with a recommended chemical flush. Some will further specify the process for the charging of the system. Some specify that a licensed pro do the job.

There are flushing kits available for about $50.

The most important item in the charging process is the vacuuming. This removes moisture. Moisture mixed in with the refrigerant turns into an acid, which eats away you compressor parts and other parts of the system.

 

[MI-SHOFEAR]

all i can say is i just did it, and it was not fun, at all. but do-able.

Jeff