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Air Conditioning - Replacing Compressor, Receiver drier, block expansion valve, etc..


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14 replies to this topic

#1 99ImprezaOSport

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Posted 31 May 2010 - 11:49 AM

OK, so first off... the system has been emptied.

I need to replace the compressor and when I got the compressor I got the whole "compressor kit" which included the compressor, receiver drier, expansion block valve, oil, and even o-rings for everything.

So I see "after replacing component, add the appropriate amount of oil to the new component:"
Evaporator 114 m (3.9 US fl oz, 4.0 Imp fl oz)
Receiver drier 5 m (0.2 fl oz, 0.2 fl oz)
Condenser 2 m (0.07 fl oz, 0.07 fl oz)
Hose 1 m (0.03 fl oz, 0.04 fl oz)

and for the compressor:
(1) Drain and measure the oil from the original compressor.
(2) Drain the oil from the replacement compressor and refill with the same amount that was drained from the original [20 m (0.7 US fl oz, 0.7 Imp fl oz) minimum]. Always use DH-PR for the replacement oil.

So now the questions:
I take everything apart, re: o-ring and place new parts and... add specified oil into each? and should I even drain/add to existing components?
Should I drain out the evaporator and refill?
Do I just turn over the compressor and drain out of either the H or L side?

I've never replaced all these components, just plugged in some additional refrigerant.

#2 grossgary

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Posted 31 May 2010 - 01:22 PM

why are you wanting to drain the compressor?

get a rough figure, looks like you have plenty of information to go with, and then add it and you're done. follow all the directions and suggestion they may come with.

this isn't an exact science, it's not like if you're 25% over or under you're going to destroy anything. get it close and you're golden. it distributes itself evenly during operation.

#3 99ImprezaOSport

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Posted 31 May 2010 - 02:22 PM

As per the service manual... :grin: ... which is always right :lol:

2) If the compressor is replaced (after stabilization):
(1) Drain and measure the oil from the original compressor.
(2) Drain the oil from the replacement compressor and refill with the same amount that was drained from the original [20 m (0.7 US fl oz, 0.7 Imp fl oz) minimum]. Always use DH-PR for the replacement oil.

When I do things I generally like to do things right the first time :lol: and since I'm not the A/C master I figure it was best to ask now and instead of later.

#4 Scoobywagon

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Posted 31 May 2010 - 02:42 PM

Being the A/C guy....

Yes, you can drain the oil from both compressors, compare them and add oil as necessary. But that doesn't tell you how much old oil is still in the system. It has been my experience that most compressors come with approximately 2 oz of oil in them (at least from the distributor I use). Your car calls for 4.9 oz total. Most of the oil in the system lives in the compressor and the receiver drier. Since you're replacing both of those components, make sure that you add 3.9 oz to the system and you should be golden.

I'd check with the distributor you got your compressor from and see how much oil they put in when they ship.

#5 grossgary

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Posted 31 May 2010 - 09:15 PM

if you're not comfortable with something then follow those directions exactly as stated and you'll be fine. the important thing to me, that I was trying to relay, is that if you're off by a good amount either way it's not going to make a difference. sometimes things need to be exact and sometimes they don't, this is one that's benign - within reason of course, i'm assuming you're obviously on point and going about this the right way :banana:. i wouldn't bother with the measuring in that much depth but for a first timer following those steps is a good move.

#6 oldgray1

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Posted 01 June 2010 - 05:54 AM

I know you don't mention this, but once you get all the oil questions sorted out, be sure to pull a vacuum on the system and charge the R134(or R12) into a vacuum. I did a R134 upgrade on a '90 Legacy four years ago and the system is still blowing cold. I didn't replace the compressor, so I did a "guesstimate" on oil amount. Be sure the oil you add is compatible with whatever be left in the system. Thanks for reading.:)

#7 99ImprezaOSport

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Posted 01 June 2010 - 06:52 AM

Thanks everyone for the words of wisdom.

Here is how things actually worked... :grin:

Replace the compressor, piece of cake. bolt off bolt on, replace o-rings done. Go to Receiver Drier, the pressure switch is not coming off easily (insert explicit words here)... do those switches go bad? I can see the Receiver Dryer needing replacing...

Now on to that block expansion valve... what a ROYAL pain to take out, they state in the Service manual to pull the entire intake... after the pain and agony of doing it "their" way... I'm going to tighten the larger and smaller metal hoses back on and "SNAP" :eek: there goes the bolt. Does this block really go BAD?

The Cheap (insert explicit words here) after market expansion block I purchased actually didn't fit properly so I ended up just keeping the original one on, well sort of... I need to either remove the bolt or get a new FACTORY one :lol: The after market one had the round button on the end that was too large to fit in tear drop shaped area...

After all that NO A/C yet... and can't you just remove the expansion block while it's on the car? One 10mm bolt and then the 2 smaller hex heads that actually hold the block on... and o-rings of course...

#8 grossgary

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Posted 01 June 2010 - 08:40 AM

i don't know, never replaced the expansion block. i've only ever replaced the one component that failed. a picture would me see what happened with that bolt you're talking about.

remove intake !! :eek:

#9 99ImprezaOSport

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Posted 01 June 2010 - 08:54 PM

Here is the "Block Expansion Valve" from my 1999 Subaru Impreza Outback Sport...

Posted Image

#10 WoodsWagon

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Posted 02 June 2010 - 10:36 PM

First off, why did the compressor need replacement?

If you fragged the compresser and burnt it all to hell inside, then the condensor could need replacement too because of all the debris in the system. The reciever dryer tends to filter that, so the evaporator and expansion valve don't get clogged.

drill and gently use an ez out on the bolt you snapped off, that connection will blow apart if you don't have a bolt in there. Or, replace the condensor too, as I think that's what that bolt threads into there right?

#11 99ImprezaOSport

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Posted 02 June 2010 - 11:34 PM

The compressor was not bad the clutch on the compressor was bad.

I tried to drill and use an ez-out, I broke off two tips of ez outs. I ended up tapping and placing a helicoil into the block... placing a steel screw into aluminum without any thread chase just doesn't make sense, but I know they do it all the time...

I realize that without that bolt it will blow off, I also think I would place two bolts on there :grin: That bold holds the aluminum bracket holding the two aluminum pipes into the block expansion valve, which has two hex head bolds which bolt it onto the ends of the evaporator.

The drier will be replaced, compressor, oil, o-rings, and a new "Fresh" charge. The block expansion valve is like new with the new helicoil :lol:

#12 grossgary

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Posted 03 June 2010 - 05:35 AM

glad you got that bolt finished off, what a mess.

ez outs are one of the worst tools available, i learned the hard way. if something *actually* comes out with an ezout then it would have come out with other better methods too. an ezout never gets out the really hard stuff, they only work on easy things....maybe that's the genesis of their names?:lol:

good left handed drill bits are the bomb for extracting bolts.

you would be fine to just replace the compressor but seems like that's not your style since you want to replace all this stuff, so doesn't really matter.

#13 99ImprezaOSport

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Posted 03 June 2010 - 06:35 AM

you would be fine to just replace the compressor but seems like that's not your style since you want to replace all this stuff, so doesn't really matter.


Well, that's how it was looking and then I read several places that when you replace the compressor your should replace the drier and even that F'N (Insert other choice words here :lol: ) block expansion valve. There is nothing worse than cutting corners and then ending up paying more in the long run.

Everything would have been a breeze but the F'N (Insert even more choice words here :lol: ) manual said to remove entire "intake" (not the engine intake but the heating-A/C intake under the dash) which is a bunch of BS. That Block Expansion valve could easily be removed without taking out that intake.

Anyway leason learned, sometimes the manual is good and other times it should be used as a conversation piece.

The system gets charged today. :banana: I'll be replacing the drier, placing the v-belt on, plugging everything up, vacuuming the system, and then charging...

#14 grossgary

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Posted 03 June 2010 - 12:25 PM

glad you're almost done, that's awesome and just in time no doubt.

you did the right thing by following the best recommendations you could find and not hosing yourself or shortchanging. but for future reference:

replacing everything is a sort of "one size fits all" suggestion. it certainly works 100% of the time. it also has a ring of emo talk from folks that want to retain credentials and market share or just like to argue armchair mechanics. once you familiarize yourself with the various failure modes and a/c systems you can start to make case specific decisions. sometimes that means everything, but not always, and actually not usually.

#15 1-3-2-4

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Posted 03 June 2010 - 05:15 PM

I have a question on the old compressor do you remove the two lines coming to the compressor to drain the oil?




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