sur6e Posted July 13, 2011 Share Posted July 13, 2011 HI all. I got an 02 Outback LLBean with the H6 3L. AC started having problems last year and would work sometimes, usually after stopping/restarting the car a few times. Eventually that didn't work either. Now it never works. Problem is the compressor doesn't engage. I know there are a ton of safeguards in the car that can prevent the compressor from engaging but I don't know 'm all, or where to find them all. I have been studying the manual and wiring etc. Things I've learned/tried so far: I know that when I jump the AC relay the compressor does work and blows cold air. I jumped the pressure switch which did not engage the compressor. I replaced the in dash controller, no difference. I ran the diagnostics on the in dash controller which tests a bunch of the sensors in the car and there are no faults. I have had the car in 4 or 5 shops and they all got to a point where they didn't want to spend more time on it and sent me on my way without pinpointing the problem. There is a TSB on the compressor revolution sensor for this model which has been tested and replaced twice with no effect. I can't figure out where this thing sits or what it's connected to myself. Since two shops said it tested bad one time and not the next I wonder if it's connected to something else that affects diagnosis and might be the real cause of the trouble. Relay and fuses are all fine. I want to check on the sensor on the evaporator in the dash, but the diagnostics by the in dash controller come back good. In the manual I see something called AC Cut Connector which I wouldn't know where to find and there is no other info about it that I can find. There is a 3 pin plug on top of the compressor. One wire goes to the relay and the two others go I think to the ECU and maybe somewhere else. I would assume that jumping the relay doesn't take those out and thus should not be a problem. I also read about a lock sensor in the compressor which stops it from engaging if it detects locking in the compressor. Again, jumping the relay should not bypass that part I think (tell me if you think I'm wrong) so it should not be the cause. I knew absolutely nothing about AC or how it all works when I started looking at it myself, so I may have some limited or even misinformation. I would really appreciate help to figure this out. I can provide the manuals in PDF if someone wants to look at them. Link to comment Share on other sites More sharing options...
bstone Posted July 13, 2011 Share Posted July 13, 2011 Add 134a. See if it turns on. Report back. Link to comment Share on other sites More sharing options...
NoahDL88 Posted July 13, 2011 Share Posted July 13, 2011 Don't just add refrigerant, if its not low the extra oil can and will grenade the compressor. Oh, you're bleeding from the head, just apply a tourniquet around your neck. :-\ Go through and clean your connections, and get the pressures checked, it very well could be low, but if it is you will want to fix the leak not keep bailing out the Titanic. Link to comment Share on other sites More sharing options...
sur6e Posted July 13, 2011 Author Share Posted July 13, 2011 Until now I've been assuming that at least one of the shops has checked pressure, and that bypassing the pressure switch confirmed pressure hi/lo isn't the problem. I'm due for an oil change so I'll ask 'm to check it. I don't understand how this could be though. Bypassing the AC relay made it run so my guess was that one of the safeguards are keeping the relay from switching. Link to comment Share on other sites More sharing options...
eulogious Posted July 14, 2011 Share Posted July 14, 2011 (edited) I would agree that your system is just low on refrigerant, and that's why the compressor isn't working. I would check the refrigerant level, and then go from there. Also be careful about manually turning on the compressor if it's low on refrigerant. The refrigerant helps move the oil in the system along, and if it's low, it might not move the oil as well, and by using the compressor without the proper lubrication, you could ruin the compressor. For a short period it's fine, but just don't do it on long trips or anything. Just a word of warning. Make sure if you add any refrigerant, that you use a gauge before and after filling up. I just picked up a low pressure gauge form harbor freight for $10. Using that gauge and a can of r134a, I can safely top off my AC system myself. Here's a little bit of experience dealing with AC for ya that I have had recently and still trying to fix... The AC system is designed to NOT BLOW UP if it's over charged. They system can handle very high pressures without exploding. How do I know this? I just did it by accident. Well my AC guy (who knows what he is doing as he teaches AC at a local university) did anyway. Granted I might have just gotten lucky... My edit: expansion valve has failed, and when trying to figure it out, we overfilled the system by ALOT. And when I say ALOT, I mean like 450+ psi ALOT, according to the manifold gauges. It was so high that the AC compressor stalled out the engine, multiple times There was SOOO much pressure in the system, that the compressor literally could not compress anymore and it stalled the car. That's alot of pressure! What's my point with all of this? DO NOT DO WHAT I DID, and NEVER OVERCHARGE AN AC SYSTEM. But I learned that even if you do something stupid and over charge the system, it is designed to handle extreme pressures without failing. I DO NOT recommended doing this AT ALL, I merely mention it to bring up the point that AC systems are very robust, and can handle alot of pressure, and they are designed to not hurt people even when people make mistakes. Take this all with a grain of salt of course, as I could have just gotten lucky. I am still VERY careful when dealing with AC stuff just because the system is very dangerous, and can hurt/kill people if it is not respected. Edited July 15, 2011 by eulogious Changed evap to expansion Link to comment Share on other sites More sharing options...
Rooster2 Posted July 14, 2011 Share Posted July 14, 2011 I would agree that your system is just low on refrigerant, and that's why the compressor isn't working. I would check the refrigerant level, and then go from there. Also be careful about manually turning on the compressor if it's low on refrigerant. The refrigerant helps move the oil in the system along, and if it's low, it might not move the oil as well, and by using the compressor without the proper lubrication, you could ruin the compressor. For a short period it's fine, but just don't do it on long trips or anything. Just a word of warning. Make sure if you add any refrigerant, that you use a gauge before and after filling up. I just picked up a low pressure gauge form harbor freight for $10. Using that gauge and a can of r134a, I can safely top off my AC system myself. Here's a little bit of experience dealing with AC for ya that I have had recently and still trying to fix... The AC system is designed to NOT BLOW UP if it's over charged. They system can handle very high pressures without exploding. How do I know this? I just did it by accident. Well my AC guy (who knows what he is doing as he teaches AC at a local university) did anyway. Granted I might have just gotten lucky... My evap valve has failed, and when trying to figure it out, we overfilled the system by ALOT. And when I say ALOT, I mean like 450+ psi ALOT, according to the manifold gauges. It was so high that the AC compressor stalled out the engine, multiple times There was SOOO much pressure in the system, that the compressor literally could not compress anymore and it stalled the car. That's alot of pressure! What's my point with all of this? DO NOT DO WHAT I DID, and NEVER OVERCHARGE AN AC SYSTEM. But I learned that even if you do something stupid and over charge the system, it is designed to handle extreme pressures without failing. I DO NOT recommended doing this AT ALL, I merely mention it to bring up the point that AC systems are very robust, and can handle alot of pressure, and they are designed to not hurt people even when people make mistakes. Take this all with a grain of salt of course, as I could have just gotten lucky. I am still VERY careful when dealing with AC stuff just because the system is very dangerous, and can hurt/kill people if it is not respected. A good story. I am aware if the system is over charged that a sensor will prevent the compressor from working. So, how and why did your compressor turn on with that much over pressure?? I am always concerned that I am adding 134a to the low port. On some cars, it is not easy to identify which port is high or low. I make darn sure that I am using the low port. That is always my main concern. Link to comment Share on other sites More sharing options...
eulogious Posted July 14, 2011 Share Posted July 14, 2011 A good story. I am aware if the system is over charged that a sensor will prevent the compressor from working. So, how and why did your compressor turn on with that much over pressure?? I didn't do anything to the electronics of the AC system, it just kept compressing. I should mention what car it was on, since I didn't do that It's a 1990 Legacy LS. So maybe on the newer stuff they added in some more safety stuff? IDK, but I did not do anything to the AC compressor or the electronics, and it just kept going till it stalled the car. I am always concerned that I am adding 134a to the low port. On some cars, it is not easy to identify which port is high or low. I make darn sure that I am using the low port. That is always my main concern. Usually the high side will be very hot usually. But you can only tell if it's hot, if it working... But the high side will be REALLY hot, compared to the low side. I also believe the drier is on the high side, so just follow the lines to find the high side. Link to comment Share on other sites More sharing options...
sur6e Posted July 14, 2011 Author Share Posted July 14, 2011 Okay, everyone keeps saying add r134a. I guess that will be the first thing I'll have done, but I wonder, doesn't the compressor need to be running while charging? If I'm not going to do it myself, how will the shop get it running? Will they just put power directly on the compressor? Maybe I should buy a manifold gauge and a can myself and add some, but I have no clue about the oil so that worries me. Thanks for the replies! Link to comment Share on other sites More sharing options...
Rooster2 Posted July 14, 2011 Share Posted July 14, 2011 Okay, everyone keeps saying add r134a. I guess that will be the first thing I'll have done, but I wonder, doesn't the compressor need to be running while charging? If I'm not going to do it myself, how will the shop get it running? Will they just put power directly on the compressor? Maybe I should buy a manifold gauge and a can myself and add some, but I have no clue about the oil so that worries me. Thanks for the replies! If the system is low on 134a, the addition of a can of refrigerant will automatically start the compressor to run. When adding 134a, turn your A/C, with controls to max cold, and highest fan setting. Don't be concerned about adding oil to the A/C system. Seldom do you ever have to add oil. If you have just a slow leak that causes the system to loose refrigerant, it will loose refrigerant only. No oil leaks out in this situation. Just be sure that you know which A/C port is the 'low" side. That is where you want to add the refrigerant. Sometimes, the port plastic cover cap is marked with an "L" on the top of the cap, indicating the low side. If you don't feel confident in doing this job, ask a knowledgeable buddy to help you, or take to a shop for a recharge. If you are a first timer doing a recharge, it is very advisable to find someone to help you that knows what they are doing. It is easy work doing this, but you need to learn from someone, who knows that they are doing. Link to comment Share on other sites More sharing options...
sur6e Posted July 14, 2011 Author Share Posted July 14, 2011 Thanks, I'll report back if I'm still alive Link to comment Share on other sites More sharing options...
Dogbone Posted July 14, 2011 Share Posted July 14, 2011 I don't know how much help this will be, but I just went through the A/C system on my '91 Loyale. On my Loyale, both the trinary switch (low AND high pressure switch) and the "belt protection system" will interupt the A/C relay if there is a problem. The temperature sensor at the evaporator does not affect this relay, it only interupts the compressor's "ground". Based on what you are saying, if you have COLD air when you jump out the A/C relay engaging the compressor, it's either a problem with the locked compressor circuit, or the high/low pressure switch (or indeed, you have lost just enough refrigerant to not activate pressure switch, but still enough to blow cold). Put a gauge on your A/C system, even a cheap one. When the system is not running, it's going to be the same pressure on both high and low side, so don't fret it, nothing is going to blow up (but wear gloves b/c escaping refrigerant can cause frostbite). A static system, you'll want to see (I'm guessing for your year/model) at least 60 or 70 pounds. When the compressor is running, you'll want to see something in the neighborhood of 30 to 40 pounds on the low side. Don't worry about the high side, but FYI it typically runs 2 to 3 times whatever is the low side pressure. And just to add, I had the same issue you are describing on my Loyale. Turned out my "belt protection sensor" was bad. I simply bypassed it by splicing two wires behind my glovebox. Details at the bottom of this thread: http://www.ultimatesubaru.org/forum/showthread.php?t=123814 Good luck. Link to comment Share on other sites More sharing options...
sur6e Posted July 14, 2011 Author Share Posted July 14, 2011 Okay one more thing. What should the pressure be when the compressor is off? If it's the same on both sides, how will I know whether it needs more freon? I imagine it will be between high and low specs somewhere? According to the manual: High 213-242 psi Low 18-28 psi While off Link to comment Share on other sites More sharing options...
Dogbone Posted July 14, 2011 Share Posted July 14, 2011 (edited) Okay one more thing. What should the pressure be when the compressor is off? If it's the same on both sides, how will I know whether it needs more freon? I imagine it will be between high and low specs somewhere? According to the manual: High 213-242 psi Low 18-28 psi While off On my car, when the A/C compressor is not running (static system), my system is around 75 psi. Again, on a static system the pressure will be the same on both the "high" and "low" side. Only when the compressor is on is there a pressure difference. Then it is "sucking" the low side, so the pressure on that side drops, and it is "pushing" refrigerant into the high side, so the pressure on that side increases. For example, on a static system, if you are only measuring, say 15 to 20 psi (or less), you should assume low refrigerant and charge it. On a properly operating system, once you hook up the can of refrigerant, and then the pressure builds enough to activate the pressure sensor, the A/C relay will close, allowing the compressor will kick on, and you would simply continue filling until your low pressure side reads between 18 and 28 psi. My recommendation: Get a psi gauge, see what pressure you have on a static (off) system. If psi is low or nothing, then assume merely a low refrigerant and charge it. If refrigerant is present and at proper psi, "hotwire" the compressor, turn on the blower fan, and verify you have cold air at vents. If no cold air, either an obstruction in system (unlikely) or bad compressor (most likely). If there is cold air, find and fix electrical problem preventing compressor clutch from engaging (a/c fuse, a/c on off switch, bad a/c relay, bad trinary/pressure switch, bad "compressor locked" detection switch, bad evaporator temperature switch). Hope this helps. Edited July 14, 2011 by Dogbone Link to comment Share on other sites More sharing options...
sur6e Posted July 15, 2011 Author Share Posted July 15, 2011 (edited) I bought a kit to recharge the system that includes a gauge that goes up to 150psi. 55-150 is red zone. I put the gauge on the low side and the needle did almost a full 360, way past the red zone. I briefly jumped the compressor while at the shop where I bought the kit and it was making a rattling noise which it hadn't done before so I turned it off quickly. I bet it's rattling because of the pressure. And it's not turning on, because of the pressure. The manual says that if pressure is unusually high on the low side it's either: -defective compressor -defective expansion valve -too much refrigerant I'm going to take it to a shop tomorrow and have them hook it up to their system and check it all out. I'll have them vacuum it out, check for leaks, etc. Question for you guys: If it's the expansion valve, and the compressor is forced to run like I did briefly by jumping the relay, could that cause the low side to build up pressure? Could it cause the low/high sides to be separated by the broken expansion valve as in that it doesn't relieve the low side when it's turned off? Edited July 15, 2011 by sur6e Link to comment Share on other sites More sharing options...
eulogious Posted July 15, 2011 Share Posted July 15, 2011 (edited) Have you checked the highside? If the low side is really high, might as well check the highside as well. I corrected my post above in saying that my expansion valve has failed on my system now, not my "evap" valve. From what I understand, the expansion valve (txv) is what really meters (or controls) the pressure of the system, and when it fails, you get some weird issues, like the low side being really high. This is a symptom of the txv failing from being stuck open. The reason for the high pressures on the low side is because the expansion valve will allow to much refrigerant into the evaporator coil, causing the pressure to rise on the low side. From the sounds of it, this is what yours is doing. The low side gets to high due to the txv being open and allowing too much refrigerant/pressure into the coils of the evaporator, so the compressor safety systems kick in and turn the compressor of, since there is too much pressure in the system. If the txv was stuck closed, like mine is, then it would seem that you need to add more refrigerant because both the high and the low side will be low. If you then try to add some refrigerant to the system you will have a low side that is low (comparatively), and a high side that is much to high. This is what happened to me, and why we got some really high pressures. My expansion valve worked at first, but then started "sticking", because it would work for a bit, then quite working, and then start working again, and then quit. When the pressures got really high, it forced the txv to open again, and start working for a short period, and then go back to it's old, sticky ways. So to answer you question, yes you thoughts are mnostly correct. If the txv is stuck open, it will cause the low side to go high, just like what is happening to you. Since the txv is open, the system is not separated, but the result would make it seem like it was. Edited July 15, 2011 by eulogious Link to comment Share on other sites More sharing options...
sur6e Posted July 15, 2011 Author Share Posted July 15, 2011 The gauge only fits on the low side and I don't have a manifold gauge. How much did it cost you to replace that? I know the part is just under 40$ but in labor I mean. From what I see in the manual it might be a hell of a job since it requires pulling down the system and needs to be disconnected from both sides of the firewall and then installed and charged up. Just seems like it'll be a bill. Thanks for the feedback everyone, finally feeling like I got a solution. :-\ Link to comment Share on other sites More sharing options...
eulogious Posted July 16, 2011 Share Posted July 16, 2011 I haven't replaced my txv yet, that comes on Sunday. Rockauto.com has the expansion valve for about $12 +shipping, so the part is not that expensive. But yes, there is some work, and you do have to evacuate the system, remove the evaporator, then re-install, and recharge. But the good news is, is that it's actually rather easy to do. The evaporator is right behind the glove box, and it is designed to be removed easily. This thread has a good explanation of what needs to happen, with pics. http://www.ultimatesubaru.org/forum/showthread.php?t=122792&highlight=expansion+valve After this weekend, I will be able to tell you exactly how easy it is Link to comment Share on other sites More sharing options...
sur6e Posted July 16, 2011 Author Share Posted July 16, 2011 Well, I found the problem, and it's not what anyone thought really. Everything is fine. I had my shop do a full check on the system and they couldn't find it, but concluded it must be the ECU or some controller. I called a Subi junk yard to get a price on an ECU and they wanted to part# to look it up. SO I pulled back the carpet, removed the metal plate, and there it was, the ECU with the sticker on top that has the part#.. made some pics, and then decided I was going to unscrew the ECU. I pulled it out and then noticed that some of the wires have been spliced in the past and were wrapped in electrical tape. I started to fiddle with it, and tried the A/C and got it working! Then I tried to put it back together and the compressor cut out. Just by rotating the ECU a little to put it back it cut out. I rotated it back to me and the compressor started up. Did that a few times. I fiddled with it some more, retaped some of the splices and got it working again and was able to put everything back. Then we went for ice cream. Link to comment Share on other sites More sharing options...
eulogious Posted July 16, 2011 Share Posted July 16, 2011 Funny how that works sometimes, eh? Glad you figured it out, and it didn't cost you that much! One suggestion though... I would go back and splice those wires up better. Don't know how good you are with a soldering iron, but I would highly recommend that you go back and solder and heat shrink those wires to make sure that you don't have another problem. If you don't want to solder, I would atleast get these to crimp the connections: http://www.radioshack.com/product/index.jsp?productId=2104092 These are better than butt connectors, and they are easier to use. Just one crimp. Glad you got it going though! Link to comment Share on other sites More sharing options...
phxmotorelectri Posted July 17, 2011 Share Posted July 17, 2011 HOW TO TELL THE LOW SIDE FROM THE HIGH SIDE: same amount of mass is flowing thru both sides... therefore: high pressure side has a SMALLER tube diameter low side has a bigger tube diameter also: high side is hot and needs to be cooled down soooo: high side goes to FRONT a/c radiator (condensor) in frontofthe car's regular radiator LOW side comes fromthe inside of the car ONLY connect to low side, you can tell everything you need to know including the conditionof the compressor just bylooking at the low side gage. The new 134-a recharge canshave acheck-valve buitinto them . If you only need 1/2 a can theother half can be saved for a year or more w/o leaking. Is this just in California or has the who;e country gone to these cans? Even from Wal-Mart some of the 134a cans have a gage built it. If so: then just have the low side pressure at about 25psi (when the compressor is on). PLUS: you do NOT need to fix an A/C leak if it is only loosing a can every year or two or 3. Come on now: a $10 can of 134a every 2 or 3 years? or... a $200-$500 fix that invariably leads to other unneeded repairs. Come on now; common sense says to just add a can and quit making a federal case out of it. Link to comment Share on other sites More sharing options...
phxmotorelectri Posted July 17, 2011 Share Posted July 17, 2011 HOW TO TELL THE LOW SIDE FROM THE HIGH SIDE: same amount of mass is flowing thru both sides... therefore: high pressure side has a SMALLER tube diameter low side has a bigger tube diameter also: high side is hot and needs to be cooled down soooo: high side goes to FRONT a/c radiator (condensor) in front of the car's regular radiator LOW side comes from the inside of the car ONLY ONLY ONLY connect to low side, you can tell everything you need to know (including the condition of the compressor) just by looking at the low side gage. The new 134-a recharge cans have a check-valve buit into them . If you only need 1/2 of a can the other half can be saved for a year or more w/o leaking. Is this just in California or has the whole country gone to these cans? Even from Wal-Mart some of the 134a cans have a gage built in. A/C recharge is ez; just get the low side pressure to be about 25psi (when the compressor is on). PLUS: you do NOT need to fix an A/C leak if it is only loosing a can every year or two or 3. Come on now: a $10 can of 134a every 2 or 3 years? or... a $200-$500 fix that invariably leads to other unneeded repairs. Come on now; common sense says to just add a can and quit making a federal case out of it. Smile! Your AC has no realproblem at all. It will be fine. Link to comment Share on other sites More sharing options...
stokie7 Posted February 7, 2016 Share Posted February 7, 2016 (edited) HI all. I got an 02 Outback LLBean with the H6 3L. AC started having problems last year and would work sometimes, usually after stopping/restarting the car a few times. Eventually that didn't work either. Now it never works. Problem is the compressor doesn't engage. I know there are a ton of safeguards in the car that can prevent the compressor from engaging but I don't know 'm all, or where to find them all. I have been studying the manual and wiring etc. Things I've learned/tried so far: I know that when I jump the AC relay the compressor does work and blows cold air. I jumped the pressure switch which did not engage the compressor. I replaced the in dash controller, no difference. I ran the diagnostics on the in dash controller which tests a bunch of the sensors in the car and there are no faults. I have had the car in 4 or 5 shops and they all got to a point where they didn't want to spend more time on it and sent me on my way without pinpointing the problem. There is a TSB on the compressor revolution sensor for this model which has been tested and replaced twice with no effect. I can't figure out where this thing sits or what it's connected to myself. Since two shops said it tested bad one time and not the next I wonder if it's connected to something else that affects diagnosis and might be the real cause of the trouble. Relay and fuses are all fine. I want to check on the sensor on the evaporator in the dash, but the diagnostics by the in dash controller come back good. In the manual I see something called AC Cut Connector which I wouldn't know where to find and there is no other info about it that I can find. There is a 3 pin plug on top of the compressor. One wire goes to the relay and the two others go I think to the ECU and maybe somewhere else. I would assume that jumping the relay doesn't take those out and thus should not be a problem. I also read about a lock sensor in the compressor which stops it from engaging if it detects locking in the compressor. Again, jumping the relay should not bypass that part I think (tell me if you think I'm wrong) so it should not be the cause. I knew absolutely nothing about AC or how it all works when I started looking at it myself, so I may have some limited or even misinformation. I would really appreciate help to figure this out. I can provide the manuals in PDF if someone wants to look at them. Hi there, I've been baffled by a similar problem with my 1998 Legacy Outback (The Japanese call them Lancaster), when turning my AC on my engine fan would come on and the idle revs changed slightly, no change in air temp though. Also the mechanical clunk from the compressor wasn't happening. I topped up the 134A with a can and built-in gauge, but nothing changed. I jumped the compressor clutch with 12 v and it kicked in as expected. I pulled the AC relay from the main fusebox under the bonnet and swapped it with a similar one from my fog lights. This fixed it! The faulty relay was a RC-5001 12v NO OXO. I'll look out for a replacement one, but as it's a hot summer now I'll keep the fog light one in until then. Edited February 7, 2016 by stokie7 Link to comment Share on other sites More sharing options...
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