How to rebuild your AC Compressor

[TERRA Operative]

I've just successfully rebuilt an air con compressor for my brothers Sera, so I thought I would share how it's done.
The actual parts will be slightly different for other compressors, but the procedure is pretty much the same. I'll update this with the Corolla bearing part number when I do my Corollas compressor (it'll probably be the same).

It's a really easy job and is able to be completed with basic hand tools. You can't actually rebuild the compressor itself as it's a 'sealed' unit, and it's WAY cheaper just to get a good one from the wrecker and use it if yours is stuffed.
The good thing about these compressors is they rarely die. Ours was buzzing, which was apparently a slightly stuffed valve inside, but it still worked. The AC guy commented that it's the first he's seen of that type that was stuffed in years.
Basically, if it makes no noises from the compressor itself and your AC is getting cold, the compressor is fine.

Ok, so what tools do you need?

Socket set
Screwdrivers
M8 bolt
Dial gauge
Magnetic stand for the dial gauge
Car battery and bits of wire
Hammer
Something with a hole in to use as an anvil (an old drum from a rear brake makes an excellent all purpose anvil)
Circlip Pliers


And parts:

Replacement compressor from a Starlet or Sera (if required)
Pulley bearing. Nachi part no. 30BGS10DST2 (30mm x 52mm x 22mm) (this part supercedes the original bearing part number) AUD$42.90 as of 24/06/2010, just be sure to check your bearing part number though.....



Here's how to do it:


Step 01:

I'll assume you have the compressor out of the car ready to go. If not, go do that. Be sure to put some tape or something over the piping in your car to stop dirt and moisture getting in. Do the same with your compressor.

First thing is to remove the clutch from the pulley.
Apply 12V to the electromagnet to engage it, this will allow you to grab the pulley to hold it still while you undo the 10mm nut in the center of the pulley.

Grab your M8 bolt and screw it into the hole. The clutch has a larger hole with an M8 thread in it, so when you screw it in, it bottoms out on the shaft (the bolt you just removed is smaller) and lifts the clutch out.





Step 02:

Once the pulley has been removed, clean it with degreaser to remove any grease or oil. The one from this Sera had years of oil leak on it so it ended up slipping and heating the clutch to the point that the metal turned blue from heat hardening.
This is no good, so I replaced it with the clutch from the Starlet compressor.


Old on the left, new on the right.

When you take the clutch off, be careful not to loose the washers on the shaft. There will be one or two there, Keep all the ones from the compressors you pull down for parts as we'll need them to set the correct clearances on reassembly.





Step 03:

Now we have to remove the pulley.
You will notice the pulley on the Starlet compressor is much larger than the Sera pulley. This is to spin the compressor faster on the Sera unit to provide greater cooling due to the large thermal load on the cabin from all the glass. We don't want to reduce the cooling capacity at all, so we will reuse the Sera pulley.
Interestingly, these pulleys will directly fit the late SC12 and SC14 (as fitted to the Previa) superchargers, although they are larger in diameter.
Theoretically, you could use an old pulley from the above superchargers to further increase the speed of the compressor for a higher cooling capacity. (pending speed ratings on the compressor....)




Remove the circlip with a pair of circlip pliers and pull the pulley off.





Step 04:

When you remove the pulley, you will see the electromagnet. Remove the circlip, then the magnet and give it all a good clean and reinstall.
This electromagnet is also the same as the late SC12 and Previa SC14 superchargers.

[TERRA Operative]

Step 05:

Once the pulley is removed, you need to pull the bearing out.
Don't stuff around with pullers etc. Just put the pulley over the hole on the anvil or brake drum etc and put a socket on the bearing from the top.
Give it a few good whacks and it'll drop out.
I used a socket that fit into the bearing when placed upside down (bolt side of the socket facing up).

Give the pulley a good clean with degreaser etc and a soft brush.

Now grab the new bearing and use the old one as a drift to tap the new one in. Be sure to hit it in evenly all around the edges only so it doesn't skew and jam up (only hit the edges so as not to shock load the balls and dent the races in the bearing) .
Also, be sure to put the small ring back in the right way up too.





Step 06:

Ok, once the new bearing is in firmly to the bottom. Reinstall the pulley on the compressor.



Stick the circlip back on to retain the pulley.



Step 07:

Now we set the clearances for the clutch.
Reinstall the clutch and the washers and tighten the centre bolt (not too tight, just nip it up).
Set up your dial gauge so it is sitting on one of the three rivets on the clutch as shown below.



Activate the clutch with the 12V battery and measure the amount of movement on the SECOND activation (well NOT the first, the clutch has to seat properly first). Do the same for all three rivets and average the results.

You want the clearance to be between 0.35mm and 0.65mm, closer to 0.35mm is ideal to account for future wear.

If it's out of spec, mix and match your washers to get in that range. You may have to file down a thicker washer if you've got too big a clearance.
Keep replacing shims and measuring until it's right.



Step 08:

Now, if you are using a compressor from a Starlet, the electrical plugs are different. Carefully remove the Starlet wiring and replace them with the Sera gear.
Give the whole lot a clean, paying special attention to the rotation sensor. It's the solid metal sensor that's retained by an Allen screw. Make sure it's perfectly clean from all dirt and metal filings (it's slightly magnetic) before reinstalling it.




Now you're ready to reinstall the compressor and get the system recharged.

Enjoy a nice cold Air Con system.

[DrNick]

Great thread Will be sure to refer to this if I need to rebuild a compressor!

[Z2TT]

Good guide good work.
More of a clutch change than a rebuild though, always wanted to know how to do a full rebuild and where to get parts for it.

Buying second hand compressors is a gamble, Usually cost $100-$200 and have leaks, where as for a couple of more hundred dollars you can get a complete rebuild.

Sealed unit? As in you cannot take it apart. First time I've heard of that.
Explain these hex bolts then?

[TERRA Operative]

Yea, it is openable, by 'sealed' I meant to treat it that way as it's not worth opening because they cost more to repair than just getting a replacement from the wrecker. They are a pretty robust design so they don't often fail.
Parts availability isn't guaranteed for all the seals and gaskets too.


That's the word straight from more than one aircon specialist.


I have a few spare old compressors so I'll look into opening them up later.

[Tweak]

I would not bother opening a/c units up unless you have a "clean room" cos any bit of dust or dirt that gets in its rooted

[TERRA Operative]

This is true.
I got two compressors for $40, so mixing and matching wasn't much of an issue for me.

[Z2TT]

Well only the re builders know where to get the parts, and that is who most of the trade send their compressors too, or swap for refurb units I believe

I know of a few people in Australia that do rebuilds of most A/C Compressors found in Toyotas, because usually old compressors that have been sitting around for a while will have a shaft seal leak from not being used in a while, other times you'll be lucky though.

[matty12]

not much gets rebuild these days anyway as most new ones are around rebuild prices.Its only the odd ball stuff that will get done or if its genuine only(as in from the dealers) as some are quite exxy.Most parts can be bought through a/c suppliers but most you would need an account for.

I also think your air gap between the pulley hub and front plate are normally set with feeler gauges, but what ever works.

[Z2TT]

Maybe for Falcon/Commodore Compressors yes. For my 1g-gte compressor would either have to be Genuine Toyota/Denso Item, or Rebuild. Full rebuild being at $270 for mine the rebuild ends up being cheaper unless somebody knows where to buy new 1g-gte compressors cheaper than this.

[TERRA Operative]

I also think your air gap between the pulley hub and front plate are normally set with feeler gauges, but what ever works.

Feeler gauges will get the approximate clearance, but because the clutch is on a rubber coupling you run the risk of pushing the clutch open with the feeler gauges and getting an incorrect reading.
The dial gauge is the same process as specified in the supercharger manual from Toyota (using the same clutch assembly), it ensures spot on results.


A replacement compressor from Toyota for the Sera/Starlet runs to the $500-600 mark or so. The grand total for the 2nd hand replacement compressor and bearing etc was under $100.
Plus I get to get my hands dirty too.

[allencr]

Can its shaft seal be replaced & is it available, or just live with the very slow refrigerant & oil leak?
Thanks.

[TERRA Operative]

I'll be pulling one completely down, probably this weekend, so I'll add to this guide with what I find.

[Z2TT]

Shaft seals are replaceable, but while you have the compressor apart it's worth to replace the rest of the seals.

Not sure where parts for a/c compressors can be purchased from though.

[matty12]

Maybe for Falcon/Commodore Compressors yes. For my 1g-gte compressor would either have to be Genuine Toyota/Denso Item, or Rebuild. Full rebuild being at $270 for mine the rebuild ends up being cheaper unless somebody knows where to buy new 1g-gte compressors cheaper than this.

So where do you get you rebuilds from???