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Replace A/c compressor instructions

PEKSAV

Full Member
Joined
Sep 7, 2006
Messages
240
Location
Minneapolis, MN
Hello
I am searching for instructions on how to replace my a/c compressor for my 2002 AV.  I donot see a post for this.  Did I not look deep enough?
thanks
 
Why do you need new compressor?

It takes PRO tools - Evac system and gage set and sometimes leak detecto kit with dye and UV light.


First hook up vacuum pump storage system and evacuate system storing old refridgerent.

Then disconnect compressor clutch wire.
remove belt
remove hoses and protect and seal ends to prevent contamination.
Remove bolts holding compressor and remove.

While doing this best to change the accumulator as well and orifice tube in it. (big aluminium can near fire wall with LP switch in it.

New Compressor may need compressor oil depends on where you go it.
reverse the take apart process and put compressor back on and everything back together.

Vacuum down system and get it to say 10" HG and hold let stand for 10-30 mins to see if this vacuum changes any.
If changes you have leaks so go find them and fix. if not continue.

Add refreidgerent back.
Start engine.
listen for any odd noise etc of belt
Turn AC on MAX fan MAX
Continue charging until full per GM charts based on temp etc.

PS when you do your self not many will warranty the new compressor since they know you are not set uo with recovering system.
 
I hope this doesn't come off as too critical, because the advice is generally sound, just off a bit on a couple of details. But here goes:

ygmn said:
First hook up vacuum pump storage system and evacuate system storing old refridgerent.

Correct in principle, but that would actually be a recovery machine required at this stage. While it will draw a partial vacuum, it's not a vacuum pump

While doing this best to change the accumulator as well and orifice tube in it. (big aluminium can near fire wall with LP switch in it.
Virtually all compressor manufacturers require those to be changed as a condition of warranty, so you better have receipts for the parts. Also, you will need to install a suction line filter OR flush the system using the system and chemicals approved by the specific compressor manufacturer.

New Compressor may need compressor oil depends on where you go it.
No maybe about it. The shipping oil should be drained from the compressor and the appropriate type and quantity of oil added to both the compressor and the accumulator. Also, once the system is all sealed back up it is necessary to rotate the compressor at least 10 revolutions by hand to ensure the compressor is not hydro-locked with oil.

Vacuum down system and get it to say 10" HG and hold let stand for 10-30 mins to see if this vacuum changes any.
If changes you have leaks so go find them and fix. if not continue.

Actually, this is the stage where your vacuum pump comes in as the required vacuum is much stronger than 10"Hg. 400 to 500 microns of Hg (0.02"Hg) is suitable. That will ensure any water is boiled out of the system at room temperature. Stronger vacuum is undesirable as it will start separating the components of the oil). 

Continue charging until full per GM charts based on temp etc.
It's done by weight of the refrigerant. So you need a scale that is sensitive enough to measure in ounces, but still capable of withstanding the weight of a 30lb gas cylinder. Alternatively you can use the small 8 or 12 oz cans and count them. If you warm the cans you will get most of the refrigerant out of them.

It's not beyond the capability of a shadetree mechanic, but you are absolutely correct that it requires a significant investment in the correct equipment. Personally, I made that investment because the number of vehicles that I maintain in our family makes it worthwhile.  The most expensive piece of equipment was the recovery machine, even used on eBay. On the other hand, I can reinstall the refrigerant with it so eventually it paid for itself. My scale came from eBay too, but it's a Chinese digital luggage scale that meets the requirements.

A Harbor Freight manifold gauge set and single stage vacuum pump are reasonably priced and work just fine for a shadetree mechanic. I have an electronic leak detector (another used eBay find) but it's not always absolutely necessary -- often a spray bottle with soapy water is needed to pinpoint the leak even after the general location is found with the detector anyway. I have a sealant detector to protect my recovery machine the first time I work on a used vehicle and I have a micron vacuum gauge to spot even the tiniest change in vacuum but neither of those is strictly necessary either.

An alternative might be to take the vehicle to an AC shop and have them evacuate the system for you prior to replacing the parts yourself, then taking it back to the shop for vacuuming and recharging.

 
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