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98 obw 2.2 251k. AC has not worked in years. System has been evacuated and open for a long time. I was going to replace compressor only until I saw black sludge like oil dripping from the compressor and metal bits. Tried to flush all components and it was fruitless. One thing led to another and I found myself replacing everything including hoses when bolts snapped. I am hear to tell you that you can remove the evaporator in 30 minutes. No you do not need to remove the dash.

Edited by msmithmmx
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Yes I replaced the condenser along with many other parts that I will list.  The box that holds the evaporator is held in with two screws. Remove the ECU that will give you more room to pull out the AC drain hose. Just pull up on the black box and slide out towards you.   I installed the rebuilt unit in 5 minutes.



Edited by msmithmmx
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After years of spotty air conditioning on my 98 OWB I decided to fix it.  Going to a professional was not an option for a car that is 20 years old with 250K miles.  The car is not worth the cost that I would  have incurred if  I went to a professional.  I have a general understanding of how AC works, access to Youtube, a home garage with some tools. Before starting any of this I was 100% sure my compressor was shot because the pulley was wobbling. As I peeled the layers back it made sense to just replace dirty, tired and broken parts with aftermarket. Minus tools I spent around $600.  I spent that money over a year so it was not as painful as a one time shot.  If you check out my part list I e Gibb f bffcould have easily shaved $100 of that total cost.  If your system still has refrigerant in it have it evacuated by a professional.  This could cost you an additional $75 to $150.  Why recovery is so much and what they do with that refrigerant is beyond my understanding.  That can be debated elsewhere.


Good Instructional Links.  I watched Eric the car guy.  His demo car is a Subaru.  Perfect for this exercise. These links will show you how to use your tools, pull vacuum, fill your system, read gauges and troubleshoot if needed.

Pulling Vacuum - 3 Hours

How To Recharge an AC System - 1 hour


Topping off the System

Radiator - (60 minutes)  Disconnect top bracket, fan electrical connectors, coolant and transmission cooler hoses.  Replace rubber hoses. They could be close to 20 years old.  I went  with molded OEM rubber lines for the transmission cooler.  I was doing the work myself so I did not mind paying more in parts.  You could use generic hoses if you wanted.

Condenser  - (30 minutes) This is held in by two bolts one at each corner at the top.  They may snap on removal.  New bolt part # is listed below.  You can get to them through the side of the grill.  No need to remove the grill and risk snapping those top plastic clips.  You may find the AC hoses are rusted welded onto the condenser.  Disconnect the AC pipe from dryer and rubber hose from the AC.  Wiggle out the condenser with hoses attached.  You will get a better angle to remove these hoses outside of the car  This is why you may need to replace these hoses. I tried to drill out the bolts but things just got mangled.   I had to replace the long AC pipe from condenser to heater.  I tried a eBay used pipe.  Here is the problem. It was still expensive.  Maybe 20% less than OEM price and its 18 years old.  It broke on install because it was corroded and old.  I went OEM new.  When you install the new condenser do so with the long pipe installed already.  You will never get them to line up easily with a good angle to tighten down that bolt properly with the condenser mounted first. Trust me.  You will need to remove some duct work around the air intake.

Evaporator  - (45 minutes)   NO you do not need to remove the dashboard.  Not even close.  1) remove the lines in the engine bay at the firewall that connect to the dryer and AC pump along with the rubber grommet. 2) Remove the glove box 3) Pull back the carpet and remove the ECU. 4) Remove the drain tube from the bottom of the evaporator.  The evaporator is enclosed in a black box as noted in a picture above. Remove the bolt and screw  as circled in the picture above.  Pull up and wiggle side to side while pulling towards you.  It is literally that simple. When installed you will need to refit the firewall grommet.  This can be tricky just take your time.  I spent more time on the AC pulley Tensioner.

Evaporator Rebuild -  (60 minutes).  There are several things going on in this box and many parts. That need to be replaced, swapped or repacked. When you have the box  out unscrew the 6 or so screws that hold the top and bottom together.  When you split the box you will have a very fragile piece of foam that sits on top of the evaporator fall out.  If you crack it just piece together with gel crazy glue made by Gorilla.  Only do the swap when you have the new parts so you do not forget how things go.  The expansion valve is covered with a piece of heavy sticky tar paper that you will need to move over from the old box and onto your new expansion valve.  There is a small piece of pipe that you will need to move over from the old box. Insert the temp sensor into the side of the evaporator by pushing it in and bending some fins. Refit the top of the box and screw together.  Refit the heavy foam around the outside of the pipes.  Use a hot glue gun and seal in the little hole where the wire passes through for the temp sensor.  Subaru used some black sealant.

AC Tensioner Pulley - (45 minutes) This part could be an issue due to age.  All of the adjustment  bolts on my original part were rust frozen. The center bolt that holds the pulley had pulled out some as well and was not catching on the bracket.  I had to press it back in.  Probably damaged when ac pump failed.   I went to the junkyard and picked one up for 5 bucks.  Between the 2 tensioners I was able to make one good one.   On eBay you are looking at $30.  Building one new OEM could be $100

Flushing - (90 minutes) I tried flushing a few things but it did not work.  I think the problem was a few things.  I had a bearing  compressor failure and my system is 20 years old.  The system was filled with black dirty oil and metal bits.  That is why I replaced everything.  I was able to keep the low pressure hose but I had to flush that with Brakeleen and then I let it dry for a few days.  Thoughts about flushing.  How do you know if you got all of the flush out?  You don't.  I can tell you this.  I tried to flush the evaporator and then I ran air through it to clear it.  When I removed it I did try to see what was left in it.  There was about 2 ounces of black flush/oil still in it that compressed air would not remove.  I probably could have flushed it with 2 cans of Brakeleen but for $60 and one hour of work I just replaced it.  If not replacing the hoses then flush all hoses with Brakleen

Receiver Dryer - (15 minutes)  For under $15 replace it.  I did reuse the sensor.  I probably would have replaced that sensor if I had thought about it beforehand.

Oil and Dye -  Add 1ml to all hoses. Condenser gets 2ml.  Dryer gets 5ml. Evaporator gets 114ml. The compressor gets at least 20ml.  My compressor shipped with no oil.  I flipped it over and tried to drain it.  Nothing came out.  No other parts I replaced shipped with oil.  I went ahead and added 20 ml.  This oil absorbs water.  When you add the oil plug the holes up if you are not immediately installing. I added the dye right into the compressor.  The dye came with the kit mentioned below.  Probably around 4-5ml would be my guess.  Add the dye so if you have  a leak you are ready to troubleshoot without having to go back and add it.  No harm with it running in the system

Transmission Fluid -  Check  ATF fluid when you are all done.  I needed to add a half quart.  This was due to removing the radiator and replacing 2 old transmission hoses.  Moving those parts around outside the car and some will pour out on the floor.

134a How Much ? -  There is some science and a gut feeling here. The sticker in the engine bay will tell you how much you need.  Weigh a full can, Weigh the adapter that screws onto the can.  Weigh an empty can. Write all of the numbers down.  I needed 23 ounces max.  I used one can 12oz without weighing anything because it was less than the total.  That first can was sucked clean in 30 seconds and I could tell it was bone dry.  I then used a second can and after 20 or so seconds I felt it was almost empty.  I screwed the plunger in.  I then shut off all of my valves.  I then unscrewed the yellow hose from the adapter at the can with the plunger down.  I weighed it and had 1.5 ounces left in the can.  That is how I know I had exactly the right amount.  Honestly I have no idea if anything would have happened if you are over by a single ounce.   I am sure someone will say it is the end of the world.  Maybe it is bad for a garage but as home mechanics we should be allowed some forgiveness.


1) Do not tighten components down until the end except for condenser  hoses and pipes along with the entire evaporator box.  Wait on the rest.  I used aftermarket parts that needed to be wiggled and moved around to get a good fit.

2) This is not exactly an afternoon job.  Something will break or you will be missing a part.  I took a year to accumulate parts and tools.  I still ran into issues.  My car was in the garage for 3 weeks waiting on parts to be shipped.  Good news is you do not need your AC to run the car.  If you are in a bind you can still use your car.  Just close the system up.  Air is bad for the internal workings of the ac system

3) PURGE YOUR YELLOW SERVICE LINE OF AIR. With all valves shut and the new 134r can is punctured open plunger.  slowly open the yellow line hose at the end where the gauge is.  Do so until you see some refrigerant come out.  Air is less dense and will be pushed out by the refrigerant.  Then tighten up the connection.  Yellow service line is now purged

4) WATCH THE VIDEOS.  Always fill the system via the low side (BLUE).  There is no reason to open the high side (RED) valve during the refill.

Final Gauge Measurement -  This reading is dependent on the temperature outside.


When everything was done my low pressure side was perfect at 52.  On the high side of the system I was on the low end for the acceptable high pressure reading at 225.  I am contributing that to an aftermarket $125 compressor.  When it was 90 degrees outside last week this new system kept me as cold as I could expect spending what I did and using 100% aftermarket key component parts.

Subaru AC Part List - $425

Receiver Drier - 4 Seasons - Amazon - Part# 83241 - $16

Expansion Valve  - Amazon - Cooling Depot Part# 39124  $15

134a - (2) 12oz cans - Amazon - Dupont Suva - $14

Spare Ring Seals -  Amazon - TECH Select - Part # 26785  $13

Long metal pipe from bottom condenser to dryer - Heuberger Subaru Online - Subaru OEM Part# - 73431AC080  - $92

Evaporator   - Amazon - Four Seasons  part # 54932 $64

Condenser -   Ebay Seller "groupdealautoparts"  Part # 73210AC050 SU3030108 - $71

Compressor - Generic Reman from  Ebay seller  "Autoac388" -    $125

AC High Side Hose - Ebay seller "pit_stop_auto" Part # 1400384 and 73424AC171 - $15


Old Parts to replace while you are there - $70

ATF Hose From top of  radiator cooler  - Heuberger Subaru Online - Subaru OEM Part# - 45521AC160  - $15

ATF Hose From bottom of  radiator cooler  - Heuberger Subaru Online - Subaru OEM Part# - 45521AC110  - $19

Coolant Hose Lower Radiator with clamps - Ebay - Subaru OEM Part#  45167AA030 - $21

Coolant Hose Upper Radiator - Amazon - Gates - 21851 - $11

Condenser mounting bolts - Lowes -  M6-1.00 X 30 - 00823671049 $1

Hose Clamp Radiator - Heuberger Subaru Online - Subaru OEM Part# -  091748014 - $2

Hose Clamp Transmission Hoses - Heuberger Subaru Online - Subaru OEM Part#  - 909170023 - $4


Tools - Purchased  Most from Amazon - $146

Mountain 8205 R-134a Brass Manifold Gauge Set with Couplers   -  $61

TMS® 3 CFM Single-stage Rotary Vane Vacuum Pump R410a R134 Hvac A/c Air Refrigerant  -  $60

FJC 6014 Vacuum Pump Adapter (from pump to Yellow AC service line)  - $4

Adapter from AC can to yellow service line -  Part # MTN8401 - $8

AC Leak Detector Kit  - Comes with UV Dye - Ebay Seller "forward-sell"  - $10

Syringe for measuring the AC oil - Picked one up at CVS - $3

Small digital ounce scale. The kind used for weighing food


Fluids: $90

134a - (2) 12oz cans - Amazon - Dupont Suva - $14

FJC 2710 A/C System Flush Kit  - $34

Prestone AF2100 Extended Life 50/50 Antifreeze - 1 Gallon  $7

FJC 2484 PAG Oil - 8 fl. oz.    $6

FJC 2032 A/C Flush - 32 fl. oz.   $23

Brakeleen  - $6


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Make sure you use a A/C system flush instead of break clean I'm not sure what brake clean will do to the seals. Also use dry nitrogen to blow it. Your biggest enemy in a refrigerant system is moisture, most if not all refrigerants are hydroscopic ( meaning they absorb moisture) and can wreck havoc in the system. Will also make it harder to pull a good vacuum on it. I pull my systems at a minimum to under 500 microns.

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Great write up particularly that evaporator work, nice! I'll be looking this up if I come across a contaminated system in the future.


Another option is replace with all used parts.


pulling a vacuum isn't required on Subarus. The normal HVAC conceptual talk about moisture is true but far from reality. Ive charged gobs of Subarus now for a decade and 100,000+ miles without one issue, there's clearly some missing information. I also started a couple threads years ago which now have many successful follow ups doing the same thing. Zero issues.


If I charged money to work on cars or lived down south I'd dig out my vacuum puller with 10 years of dust or buy a commercial one.

Edited by idosubaru
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Make sure you use a A/C system flush instead of break clean I'm not sure what brake clean will do to the seals. Also use dry nitrogen to blow it. Your biggest enemy in a refrigerant system is moisture, most if not all refrigerants are hydroscopic ( meaning they absorb moisture) and can wreck havoc in the system. Will also make it harder to pull a good vacuum on it. I pull my systems at a minimum to under 500 microns.

I used the break clean on the disconnected pipes and hoses. I ran it through and had it pour out the bottom. I would not use it on anything else.

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  • 5 years later...

Back to the evaporator case, msmithmmx posted a photo of the left side with the evaporator in the case (July 19, 2017). My project is to replace that little thermistor in plain view on that photo. Anybody know if its possible to loosen a few obvious mounting bolts, pry apart a little, and get in there where the fat foam meets up with the heater section?

I thought maybe separating the bottom half of the case from the top half, but it seems there are little screws on the backside and too hard to reach. You see, I don't want to discharge the system and drop the whole evap case.

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System evacuation is costly because the government says I have to have a license to buy the refrigerant (in 30lb cylinders) and the EPA can fine me if I don't prove that I'm recovering the stuff, etc. The machine to do this effectively and properly filter the refrigerant so it doesn't contaminate my system is about $6,000. The filters have to be changed, it requires an operator, etc, etc. 

Not to mention the overhead of running a shop - insurance, payroll, rent/mortgage, etc. It would make your head spin right off your shoulders. 

That's why nearly all shops have a one-hour minimum. By the time I make an appointment, talk to the customer about their concerns and expectations, perform the work, write up the invoice, etc - it's just not possible to not charge for these services. 

AC repair is actually pretty simple for the most part. There's no magic to it. For the most part Subaru systems tend to be easier than most. Usually bad Shrader's, bad o-rings, or a bad compressor. Sometimes hose crimps or a hole in a condenser. Subaru's tend to be fine with replacement compressors without touching anything else or flushing anything. The receiver/dryer acts as enough of a filter to keep the debris from plugging things up so typically you just throw in a new or used compressor, a few ounces of oil, some new o-rings, and charge them. 


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On 7/14/2023 at 7:51 PM, fisher54 said:

My project is to replace that little thermistor in plain view on that photo. Anybody know if its possible to loosen a few obvious mounting bolts, pry apart a little, and get in there where the fat foam meets up with the heater section?

In a similar situation, I have installed a new evaporator temp sensor by simply cutting a small access hole in the case, placing the device between the fins and then patching the hole. I did not risk separating the often brittle plastic case in fear of doing more harm than good. I also left the old thermistor in place and just clipped the leads. 


I've done all of my own A/C work for the better part of 30 years and for more than 20 years, I ran propane/butane gas in all my R12 vehicles. About 5 years ago, I began changing everything over to R152a (Dust Off cans propellant) as the need arose. I run 152 in my 1965 Corvair, an 87 B2000 and my 87 DL wagon. Soon, my 2003 WRX will change from 143 to 152 after a hose failure last Saturday. There are plenty of tutorials online about using 152 but it is a DIY solution. Don't expect a professional shop to mess with that.

Edited by azdave
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