AC Not Working 2002 Impreza

[idosubaru]

4 hours ago, Daskuppler said:

So I checked the clutch air gap and it was at about .23, which is way out of spec.  I pulled the clutch and removed one shim from the shaft and put it all back together.  It seems to be working better, but I noticed the side vents blow cold air and the middle vents blow coolish air.  When the compressor cycles off the center vents turn hot (like the heater is on) and the side vents turn coolish before the compressor comes back on.

Any thoughts?

can you remove another shim?

Good job checking the clutch. Sounds like the clutch is shot or the AC is fine but you have blend door issues like the controls aren’t fully and nominally moving the blend door mix. I don’t think this is your issue but I don’t want to assume too much via the limitations of online diagnosis!

Well done removing a shim, slick move.

I’m not we’ll versed in the AC clutches since they fail so rarely on Subarus and I can usually easily install another compressor with little testing, but I’d assume the improvement means clutch engagement issues that are only partially resolved via the shims. 

Have you already replaced the compressor?  I’d assume the compressor or clutch needs replaced. 
 

WAG:  Maybe the compressor or bearings are tight and requires greater than normal exertion to rotate.  This would explain premature clutch wear, why removing shims helped, but didn’t totally solve it, and weak overall compressor performance. 

[laegion]

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Edited May 12, 2022 by laegion

[laegion]

2 hours ago, idosubaru said:

can you remove another shim?

Good job checking the clutch. Sounds like the clutch is shot or the AC is fine but you have blend door issues like the controls aren’t fully and nominally moving the blend door mix. I don’t think this is your issue but I don’t want to assume too much via the limitations of online diagnosis!

Well done removing a shim, slick move.

I’m not we’ll versed in the AC clutches since they fail so rarely on Subarus and I can usually easily install another compressor with little testing, but I’d assume the improvement means clutch engagement issues that are only partially resolved via the shims. 

Have you already replaced the compressor?  I’d assume the compressor or clutch needs replaced. 
 

WAG:  Maybe the compressor or bearings are tight and requires greater than normal exertion to rotate.  This would explain premature clutch wear, why removing shims helped, but didn’t totally solve it, and weak overall compressor performance. 

No, the clutches just wear, it's normal and removing shims is a common fix. It sounds more like it needs to be completely evacuated and properly charged now that the leaks and compressor clutch issues are fixed. Also, maybe look into the blend door, it seems like, or maybe the flow to the heater core is not being shut off properly when the a/c is turned on...

[Daskuppler]

The blend door control is very stiff so maybe replacing the cable would be beneficial.  The heater usually works pretty well, but it could be out of whack to where it's not turning the heat completely off.  I'll dig into it a little more and see.  It might be time to take it to the shop.

Do these cars have a pressure switch?  I don't see one when I look for parts at the auto parts store.  I'm guessing it's all controlled by the ECM, but I'm not entirely sure.

 

If I remove another shim, there is no gap so I just removed the one.

Edited May 12, 2022 by Daskuppler

[idosubaru]

5 hours ago, Daskuppler said:

T.  I'm guessing it's all controlled by the ECM, but I'm not entirely sure.

 

There's no computer control - just a very basic on/off logic circuit.  You could find a factory service manual A/C page (or you may already have it?) and see all the components to the system, it's not much.  

[heartless]

look here for FSM info: http://jdmfsm.info/Auto/Japan/Subaru/

 

[Daskuppler]

Since I am getting some cold air and then it cycles warm, I am assuming nothing is clogged.  Could this be a bad expansion valve, or is it more likely compressor?  The onl y things not replaced are the exanpsion valve, compressor, and evaporator...

[laegion]

1 hour ago, Daskuppler said:

Since I am getting some cold air and then it cycles warm, I am assuming nothing is clogged.  Could this be a bad expansion valve, or is it more likely compressor?  The onl y things not replaced are the exanpsion valve, compressor, and evaporator...

Did you have it evacuated and recharged by a shop yet? If not, I would do that, it's cheaper than throwing more parts at it. I paid about $130 to have the A/C recharged in my '95 and they put it on the machine and evacuated it and left it under vacuum for a bit. Charged it up and ended up putting an extra LB of refrigerant in. $100 for the labor and $30 for the lb of refrigerant. They were done with it in a few hours. Worked awesome after that. Before it would sometimes be kinda cold, sometimes warmish; but never right. After, it was ice cold.

Edited June 4, 2022 by laegion

[Daskuppler]

16 minutes ago, laegion said:

Did you have it evacuated and recharged by a shop yet? If not, I would do that, it's cheaper than throwing more parts at it. I paid about $130 to have the A/C recharged in my '95 and they put it on the machine and evacuated it and left it under vacuum for a bit. Charged it up and ended up putting an extra LB of refrigerant in. $100 for the labor and $30 for the lb of refrigerant. They were done with it in a few hours. Worked awesome after that. Before it would sometimes be kinda cold, sometimes warmish; but never right. After, it was ice cold.

I did not. It was placed under vacuum and charged through the gauges so a shop isn't really going to do it any different.  I'm trying not to spend the money sinces it's over $200 to have it done here

[Daskuppler]

This issue had been resolved. I be had the system evacuated, I replaced the compressor, expansion valve, all associates o-rings, cleaned off the evaporator (the previous owner apparently did not have a cabin air filter in so it was covered in crap), put the system under vacuum for 90 minutes, recharged, and it's good to go.

[forester2002s]

1 hour ago, Daskuppler said:

the previous owner apparently did not have a cabin air filter in

I bought my 2002 Forester new. It was without the cabin air-filter when I picked it up. Subaru must have been penny-pinching back in 2002!

[laegion]

1 hour ago, forester2002s said:

I bought my 2002 Forester new. It was without the cabin air-filter when I picked it up. Subaru must have been penny-pinching back in 2002!

They generally just left them out unless it was a premium model, like the LL Bean. Thankfully there is still a spot for them.

[Daskuppler]

Randomly I started getting a loss of air flow despite the blower running on high. I can hear air moving, but there is very little out of the vents. After inspecting further, I found no leaks in the duct work and all controls are working fine.  I did notice that when it is set to recirculation, the low pressure line has ice on it in the engine bay.  This is only present on recirculation. Taking in outside air results in no ice. 

I would imagine the lack of airflow is because the evaporator is icing over as well (I get air flow back pretty quickly if I take in outside air).

 

What would cause this?

[azdave]

Of course moisture can freeze on the evaporator coils and will eventually block the airflow almost entirely until it melts away. You can do that manually by turning off the compressor for a few minutes or by selecting hotter outside air instead of recirculating if that works for you. The icing issue can be caused by low airflow in general (clogged cabin air filter maybe) or a lower than ideal A/C charge which drops the saturation point of the vapor below 32F. If you live in a humid area, icing is more of a nuisance than it is for me here in the dry desert. 

[Daskuppler]

31 minutes ago, azdave said:

Of course moisture can freeze on the evaporator coils and will eventually block the airflow almost entirely until it melts away. You can do that manually by turning off the compressor for a few minutes or by selecting hotter outside air instead of recirculating if that works for you. The icing issue can be caused by low airflow in general (clogged cabin air filter maybe) or a lower than ideal A/C charge which drops the saturation point of the vapor below 32F. If you live in a humid area, icing is more of a nuisance than it is for me here in the dry desert. 

I live in Colorado.  It's been humid for colorado standards, but probably only about 35%.  The cabin air filter is new, there actually wasn't one in there when I started this fiasco.  I cleaned off the evaporator while it was apart, it was caked with 20 years of debris.  When everythin works, there is plenty of air flow.  I'll check the charge and see if it needs a little more.  Hopefully it's that simple.  I can always just run it with outside air, but I would prefer the system to work properly.

[Daskuppler]

I added a little more refrigerant, the guage reads about 36pis with compressor running.  The system still ices up when on recirculate.  Filters are clean and new.  I did notice that the filters do not sit flush in the filter box so when the recirculate door opens, the side of the filter obstructs about an inch of the opening.  Is this normal?  The opening is in no way obstructed and I feel like there is plenty of room for air flow, just something I noticed.

[azdave]

Does the compressor cycle on and off in moderate temperatures? My 2003 WRX will cycle the compressor on an off to prevent freezing solid like you describe. Do you ever hear hear a relay switch clicking inside the dash when the compressor turns off and on? Does the compressor stay on full time, even during less than hot days? Maybe that switch is not reading the evaporator core temperature so it doesn't turn off the compressor when the core gets below freezing.

 

Edit. The relay switch I mention clicking above is actually thermister that is silent and provides a readiing to the ECU. I was thinking of my 87 that has the manual relay. Sorry for the confusion.

Edited July 12, 2022 by azdave

[Daskuppler]

1 hour ago, azdave said:

Does the compressor cycle on and off in moderate temperatures? My 2003 WRX will cycle the compressor on an off to prevent freezing solid like you describe. Do you ever hear hear a relay switch clicking inside the dash when the compressor turns off and on? Does the compressor stay on full time, even during less than hot days? Maybe that switch is not reading the evaporator core temperature so it doesn't turn off the compressor when the core gets below freezing.

I guess that's a possibility.  It's been 90 plus since I've been troubleshooting it. When the compressor first went in I recall it cycling just fine. It was not turning off when the lines had ice on them though.

[azdave]

Update; I edited my post you quoted above because I just realized I confused my 87 Subie with my 2003. In 2003 there is a thermister device in the evaporator core that sends a resistance reading to the ECU which then cycles the compressor on and off to prevent icing. You will not hear clicking under the dash with that sensor but it is still supposed to prevent the evaporator core from becoming too cold and forming ice. It's really hard to get at that sensor so I would not put a lot of effort into it if you can simply select outside air to reduce the icing.

[Daskuppler]

55 minutes ago, azdave said:

Update; I edited my post you quoted above because I just realized I confused my 87 Subie with my 2003. In 2003 there is a thermister device in the evaporator core that sends a resistance reading to the ECU which then cycles the compressor on and off to prevent icing. You will not hear clicking under the dash with that sensor but it is still supposed to prevent the evaporator core from becoming too cold and forming ice. It's really hard to get at that sensor so I would not put a lot of effort into it if you can simply select outside air to reduce the icing.

I'm guessing that's the little black thing that was stuck in the evaporator?

If I recall correctly I put it all back together and forgot to put that back in the evaporator.... that's likely the issue, I'll see if I can get it back in there without pulling the evaporator

[azdave]

12 hours ago, Daskuppler said:

I'm guessing that's the little black thing that was stuck in the evaporator?

If I recall correctly I put it all back together and forgot to put that back in the evaporator.... that's likely the issue, I'll see if I can get it back in there without pulling the evaporator

There you go. It's not very big so maybe you can split the case halves slightly to get it back in there. In my 2003, the compressor was cycling way more often than I wished (or needed in the dry desert) so I paralleled a potentiometer across the thermistor leads so I could adjust the resistance reading seen by the ECU. Now the compressor cycles much less, I'm more comfy and still no ice issues. It has been 114F here the last few days and even in those temps the compressor would cycle occasionally.

[Daskuppler]

6 hours ago, azdave said:

There you go. It's not very big so maybe you can split the case halves slightly to get it back in there. In my 2003, the compressor was cycling way more often than I wished (or needed in the dry desert) so I paralleled a potentiometer across the thermistor leads so I could adjust the resistance reading seen by the ECU. Now the compressor cycles much less, I'm more comfy and still no ice issues. It has been 114F here the last few days and even in those temps the compressor would cycle occasionally.

I got it in and it seems to be working.  I think it was originally pretty close to the middle of the core...I got it about 1/3 of the way back.  It all seems to be cycling normally now.  Thank you!

 

Edited July 13, 2022 by Daskuppler

[azdave]

You are welcome. I'm not that good at all things Subie but I'm glad I could help on this item and give back to the community.