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Without seeing it that's a reasonable guess the the compressor needs to be replaced. So you also need an expansion valve - or hope you can unclog it. And a flush kit. I don't know what to tell you about being full retard both high and low after being off for 2 hours. It's nothing good. It's either an interesting clog (which is why I'm saying flush it) or you have some interesting gases in that system (contaminated). And while it's hard to tell with a video, that compressor sure does sound spanked. I hate to tell you to just shotgun so much stuff.....but the system seems truly well hosed. Anything you replace that didn't need to be replaced RIGHT NOW would probably be making GBS threads the bed entirely pretty quickly anyway. If you get that whole list of parts.......there's not much left to be wrong anymore.
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Apr 13, 2014 03:38
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Yeah, honestly that compressor sounds pretty well lunched. BTW, those numbers you gave should actually be PSI, only the red numbers on the low side gauge are in/Hg; that's a measurement of vacuum.
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Apr 13, 2014 03:53
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Motronic posted:Without seeing it that's a reasonable guess the the compressor needs to be replaced. So you also need an expansion valve - or hope you can unclog it. To add to this, if some of that stuff is presently eating itself alive and contaminating the poo poo out of the rest of the system, it'd probably be wise to just replace everything, else contaminated parts left in the system may pass the gift on to the new parts you put in. Flushing it might help, but I sure wouldn't want to trust it. I guess it depends on what you find when you open the system, if there's gross poo poo and corrosion or metal powder/flakes everywhere, I'd just shotgun it and replace drat near everything in the system. If it looks mostly clean, maybe just replace what seems to be bad.
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Apr 13, 2014 04:00
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Motronic posted:So you also need an expansion valve Expansion valve is $9 so I'll just pick it on up. Final list: 1 Compressor 1 Condenser 1 Pag 46 Oil 1 Gasket Kit 1 Receiver drier 1 Expansion Valve All told I'm looking at $259 in parts and who knows how much time in my own labor. kastein posted:I'd just shotgun it and replace drat near everything in the system. Probably going to roll the dice on the evaporator as I don't want to open up the dashboard to get at it. Fucknag posted:Yeah, honestly that compressor sounds pretty well lunched. Fucknag posted:BTW, those numbers you gave should actually be PSI, only the red numbers on the low side gauge are in/Hg; that's a measurement of vacuum. Thank you all for your help diagnosing. I'm sure I'll run into more problems with the install so I'll be around for a bit.
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Apr 13, 2014 05:15
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Well, the evap core is just a big aluminum radiator inside the dash, so you won't hurt it at all by flushing it and back flushing it with some sort of solvent if it turns out to be full of gunk. So that's fairly reasonable.
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Apr 13, 2014 11:24
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Goddamnit. My compressor also whines a bit. Not as bad as that (probably half as bad), but it's a noticeable whine inside the car if the windows are down, even at idle. With the windows up, it's a faint whine (above about 3k) that I was hopefully chalking up to the serpentine belt tensioner. Gonna be dropping a good chunk of cash at the parts store Monday for brake stuff, may as well borrow a gauge set and see just how hosed I am.
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Apr 13, 2014 12:16
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I am pretty sure I need to recharge my AC, but I want to run it by the thread before I start any work. I was used to Land Rovers and the superior TXV. 05 Yukon XL - Its a capillary tube system with rear AC I noticed that the air coming from the vents doesn't get super cold until you start moving the truck. I can hear a hiss on the inside, so I know its doing its liquid to gas change thing. I need to go throw the gauges on when its actually warm enough (above 70) to do a more accurate readings etc. Sounds like its just low on R134a. And I know with a million miles of lines, its bound to leak a little. I figure when I do a small charge I want to dump some dye in as well to see if there are any leaks. I also wonder if I need to double check my relays because this is the year they switch from mechanical fans to electronic.
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Apr 17, 2014 16:59
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BrokenKnucklez posted:I also wonder if I need to double check my relays because this is the year they switch from mechanical fans to electronic. Start it cold with the AC off. Check that none of the fans are on. Turn on the AC. A fan should immediately come on over the condenser. If not, start right there. Because it sounds like that could be the issue. But, yeah.....they leak a lot more with rear AC. It's just a lot of drat hose.
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Apr 17, 2014 17:04
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Yeah, I figured it might be a little low. Its just been such a bitch trying to get some kind of good readings when it goes from 65-70 to 30s at night.... Plus I am just a "hot" person in general and like it cold. Its not like I am goony fat or anything, I just like it cold.
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Apr 17, 2014 17:07
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Is it when the truck actually starts moving, or will it also do it if you rev the engine in park/neutral? If it's the latter, it could just be the low charge; too low to get effective cooling at idle, but with some revs the compressor is turning faster and building up more pressure, enough to get at least some cooling. Can't get a definitive answer until you get static and running pressures, though. Ambient temperature doesn't matter too much, most gauges will have usable temperature markings down to at least 50. Alternately, you can look up a chart that lists static pressure for any temperature (like this one) and see if pressures match up. Remember that if it's within a few hours of the truck being driven, the engine bay will be warmer than ambient, so if it's 65 out, maybe use 70-75 for your readings (or higher if it feels warmer; an air thermometer in the engine bay would be ideal.) Once it's running and the cooler air is actively being sucked over the condenser, use the outside air temp or a bit over, and use it and the running pressure chart in the OP to check what it should be. E: Also what he said about checking the fans.
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Apr 17, 2014 17:16
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Preoptopus posted:So just got sent to an A/C seminar through work and bad news folks! Enjoy r134a while it lasts cause the industry is switching over to r1234yf really soon! What does this mean?! Well, if you have an old car that runs out of r134a, your hosed. The knew systems cannot legally be retrofitted to any old car. New cars will have closed systems and the only way to pressure test is with a scan tool. compressors are crazy complicated and will no longer have clutches and be running at all times. (This is already in production) Soon you will have to do oil changes on your A/C compressors. Shops will have to buy all new equipment. Oh and the knew stuff costs around $1300/10 pounds. And its flammable! As someone who is primarily a driver rather than a mechanic, my only question is this: Will new A/C systems blow colder? That's pretty much the only thing I care about : the ability to summon a Nor'easter on command and point it directly at my face. I want to see loving icicles. I never did a comparison between R-12 and R-134a myself, but rumour has it that the old A/C systems were more effective than new ones. I wonder if a) there really is any truth to that and b) if we'll be able to go back toward better cooling with the new systems?
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Apr 17, 2014 22:42
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R12 systems generally were better, however new systems have been 'up-sized' to accommodate the reduced efficiency of R134 and work just fine. You really only get screwed in cars that were manufactured to use R12 and converted to r134. That said, my converted 23 year old vehicle blows ice cold on the hottest days (I get condensation on the vents), so I think it's mainly important that your system is in good working condition.
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Apr 17, 2014 23:00
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David Corbett posted:As someone who is primarily a driver rather than a mechanic, my only question is this: Will new A/C systems blow colder? That's pretty much the only thing I care about : the ability to summon a Nor'easter on command and point it directly at my face. I want to see loving icicles. It's less about "newer" and more about "properly designed". As revmoo said, R12 is simply more effective, but if you upsize everything you can get the same BTU output from R134a or really anything else. There was a particularly bad time in the early/mid 90s when R12 was being phased out but not every make/model could accommodate stuff that was really big enough (until the next model refresh) so you'll find some clunkers in regards to AC performance in that time. Also, most "budget domestics" have a capillary tube and accumulator system which can work fine, but is pretty much junk compared to a TXV. More recently, variable displacement compressors are becoming common and do a really nice job but like any other newish technology being put into the mainstream they're not without some issues.
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Apr 17, 2014 23:15
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So it's April in Arizona, which means I have about -30 days to get my AC fixed. To recap from sometime last year, I did the R-152a conversion on my system, new oil/dye/dryer/o-rings, etc. Consistently, the charge (read: blowing cold) would only last two months tops. After vacuuming out and refilling though, high- and low-side pressures were always in perfect range, and obviously the compressor cycled appropriately and the clutch sounded fine. The problem is that there's a loving leak somewhere and I can't find it even with the dye in the system. Will it be in my best interests to go to a shop that does "A/C leak tests" and see what equipment/methods they use? I'm assuming that the simplest way to find the leak would be to empty the system, then put pressure into it via nitrogen or the like, rather than trying to hold it under vacuum. Hell, I don't even need a shop to do the work for me afterwards; I just need to find out which goddamn hose, fitting or whatever to replace. Maybe the condenser. Who knows. Reminder: 1985 RX-7, originally R-12; with R-152a it had vent temps of 38 Fahrenheit. When it worked, it worked.
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Apr 18, 2014 07:44
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Typically they'll use nitrogen to detect that a leak exists, but there's no way of locating it since the atmosphere already has nitrogen; there are sniffers, though, that can detect refrigerant in the air, though I don't know if they're specific per refrigerant or if they can just detect any halocarbons. You are using a UV light to check for the dye, right? I'd check inside your airbox too, to the extent possible; it's possible the evaporator is leaking and needs to be replaced, but a leak there wouldn't show up in the engine bay, unless I'm dumb and RX-7s have the case in the engine bay like some trucks.
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Apr 18, 2014 08:07
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Fucknag posted:Typically they'll use nitrogen to detect that a leak exists, but there's no way of locating it since the atmosphere already has nitrogen; there are sniffers, though, that can detect refrigerant in the air, though I don't know if they're specific per refrigerant or if they can just detect any halocarbons. The other place I've found "leaks that I can't find with dye" are the drat valve cores of the service ports. Because you expect them to have dye on them already.
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Apr 18, 2014 16:16
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Motronic posted:The other place I've found "leaks that I can't find with dye" are the drat valve cores of the service ports. Because you expect them to have dye on them already. Had that bite one of my coworkers in the rear end at Sears, we ate a complete vac+refill plus diagnosis and repair at an a/c specialist shop because he didn't check the service ports and declared the system ok. Did an R12 recharge today! Friend has an 87 Toyota Pickup, a/c has never blown cold, but the compressor engaged so we knew there was at least something in it. Hooked gauges up and static pressure was perfect, so we dumped 2 cans in and the a/c blows an excellent 45 degrees. However, at the end pressures looked a bit low, 15/150 (I was looking for 20/205), but like I said the air came out cold. Does that sound like it might still be slightly undercharged? Total system capacity is 28oz, I put in 2 12oz cans, but I don't know how much or how little was in beforehand.
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Apr 19, 2014 01:09
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Motronic posted:The other place I've found "leaks that I can't find with dye" are the drat valve cores of the service ports. Because you expect them to have dye on them already. Funny thing: I actually replaced the valve cores in October the last time I charged the system. Didn't seem to help. About a year ago when I had the blower motor removed to check it out, I also shined my UV light all over the evaporator and didn't find anything. It's frustrating as hell.
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Apr 19, 2014 06:05
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Fucknag posted:, 15/150 (I was looking for 20/205), but like I said the air came out cold. Does that sound like it might still be slightly undercharged? Total system capacity is 28oz, I put in 2 12oz cans, but I don't know how much or how little was in beforehand. It sounds a bit low, and also like the compressor has seen batter days (no surprise). Shoot for the appropriate low side pressures and just be happy with how much the compressor is able to make on the high side. Or don't. If the thing is blowing cold as is and isn't freezing the evap on humid days everything is good enough.
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Apr 19, 2014 15:50
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Motronic posted:It sounds a bit low, and also like the compressor has seen batter days (no surprise). Shoot for the appropriate low side pressures and just be happy with how much the compressor is able to make on the high side. Fair enough. I should note that at times it got up as high as 195 on the high side; it's possible the evaporator was partly freezing over during the charging process and making the readings wonky. That said, he texted me today and said his girlfriend was complaining and made him turn it off. I'm marking this one a success.
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Apr 20, 2014 02:26
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Well I did some quick checking. I swapped relays with another good relay and the fans didnt kick on, So I just jumped the relay and the fans kicked on. I didnt dig the gauges out, which I am going to do tomorrow. Its definitely short cycling though, I purchased a can of 134a and plan to do it tomorrow. I can hear it hissing in the dash when the compressor kicks on then it stops right away. I purchased the one with dye in it and see what happens. Its pretty much a 10 year old truck with a million miles of pipe, its bound to just have leaked some.
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Apr 20, 2014 05:21
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So the relay secondary circuit (that sends power to the fans) is good; how's the primary circuit? Typically you'll have constant 12V to the socket, with the switch in the cabin grounding the other pin and completing the circuit. If a known good relay doesn't work that's where I'd start looking.
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Apr 20, 2014 06:35
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Fucknag posted:So the relay secondary circuit (that sends power to the fans) is good; how's the primary circuit? Typically you'll have constant 12V to the socket, with the switch in the cabin grounding the other pin and completing the circuit. If a known good relay doesn't work that's where I'd start looking. Well, thats what I thought, but after looking, the fans don't kick on till a certain temperature. And with all the stupid poo poo GM does, I wouldn't be shocked.
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Apr 20, 2014 06:37
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Cooling fans sure, but A/C? I'd believe it too, but if so that's asinine.
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Apr 20, 2014 06:42
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Hey what do you know.... it relies on another sensor to turn the fans on. But FWIW GM must have adopted after my Range Rovers system  . It only turns the fans on when the high pressure side gets to X amount of pressure. And I have only seen those fans kick on once or twice in the entire time I owned my P38, and it was on a 102 degree day. So I am guessing it runs a similar setup. I honestly think its just low on 134a.
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Apr 20, 2014 06:54
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Got out and charged the AC a little today. Static pressures on both sides measured around 75 lbs, and the ambient temp around 72, so I am taking that as heat absorption (its a black truck). First off... I added around 3oz-4oz of R134a in a system that needs, well, A LOT. The compressor quit short cycling, and the Capillary tube system started making some noise, and added little more in increments. Then Voila! The aux fans kicked on because now I was building some pressure in the high side.  That's with the fans on, when the fans are off it jumps up to 200ish. I kinda feel like the compressor is getting weak, and for these years of trucks, its not uncommon. The vent temps felt pretty good (I need a thermometer, but were much colder), but I feel like I am going to have to come back when its a little warmer out and see where things are. Also, for any one who owns a Suburban/Tahoe/Escalade/Yukon 2000-2006, the rear air portion is controlled by a Thermal Expansion Valve and the front is a cheap 98 cent part. Why the gently caress could they not add a 10 dollar part is beyond me. Edit: It was definitely getting warm where I was standing, and I know 200 ish is slightly out of line with the chart you provided in the front, but I chalked it up to engine heat, and other outside forces. I don't think I really overfilled anything, unless you see something I did wrong. When I turned the truck off the system definitely is working correctly because the pressures started to align them selves to around 80. Which falls inline with where the high side WAS at. A little at a time cant hurt right? Edit again. The low side and high side ports are fairly close together and the capillary tube is between that. Its making a hiss, which would tell me its still low right? Or do those things always hiss? BrokenKnucklez fucked around with this message at 17:12 on Apr 20, 2014 |
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Apr 20, 2014 16:51
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Quick little update: I think I have a blend door issue, on my drive in I could feel it get cold then quickly warm up then get cold again. I turned one of the rear ac vents on and let it blow on me, and it never changed... nice and cold. After a couple of miles the front vents started making cold air and lots of it and the rest of the drive was very cold front air. But it definitely needed a top up on 134a. The air is much colder and the compressor is not short cycling anymore.
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Apr 20, 2014 20:12
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BrokenKnucklez posted:Edit again. The low side and high side ports are fairly close together and the capillary tube is between that. Its making a hiss, which would tell me its still low right? Or do those things always hiss? OK so was this the question you wanted me to answer out of this wall of stream-of-consciousness that you mentioned in the chat thread? If so.....yeah.....some of them are simply noisy. But if it's really noisy (which is difficult to define over the internet) the tube is probably clogged with poo poo. If it is, and you already have a bunch of refrigerant in there and you get it working acceptably just deal with it. If you can't, I'd order a new accumulator (have fun with that - there are like 6 that may or may not work based on the part numbers I've dealt with in suburbans of that vintage) and a tube, open it up and see what you have. If it's a little bit of stuff carry on. If it's scary stuff it time to figure out where it came from, fix that, flush and then put it back together. And this is the problem with DIY A/C. Everything would be so much easier if we could reasonably get our hands on a Robinair that would recover, filter and allow us to refill the same refrigerant. Because we can't sometimes you just got to go with the best guess and carry on.
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Apr 21, 2014 04:01
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Exactly what I needed to hear. Sorry for the wall of poo poo.... just figured I would get every thing put down in case I miss something.
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Apr 21, 2014 05:22
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This is more curiousity, since I no longer have the vehicle (and got rid of it about 14 years ago). 1980 Ford F-150. The a/c was always cold, though always with a really noisy compressor (loud grinding noise whenever it was on). Whenever I ran it though, within about 30 seconds of shutting off the a/c (or after parking), you'd hear a hissing, then a loud whistling that lasted about 10-15 seconds. What the hell was that whistling?
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Apr 21, 2014 06:31
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Fords have a vacuum component to their fan/AC position selector switch. My Ranger does the same thing, and my dad's previous-gen Ranger also does this. It's just the vacuum dissipating noisily, the older the seals in the switch get the louder it tends to be.
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Apr 21, 2014 07:37
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It wasn't that; it was something from under the hood. If you grabbed the A/C lines, you could feel them vibrating with the whistling. This was way, way, way too loud to just be the vacuum motors - it was ear-splitting loud if you were standing in front of the truck at the time. Inside? Much quieter. It was loud enough that you could hear it halfway across a parking lot. I eventually did replace the vacuum motors, plus control panel, for the usual reasons - that got the mode selector working properly, and got rid of the hissing from under the dash. Had nothing to do with the whistling though. The whistling would only happen if I'd been running the a/c. Vent? No. Floor? No. Bi-level? No. Off? No. I could force the whistling to start while driving if I ran the a/c for a bit, then turned it off, while driving. Vent and normal a/c both activated the same vacuum components; max added to this by closing off the fresh air intake. the tl;dr is it would only whistle if the mode selector was on a/c or max a/c for a bit. No other position would make it whistle, and the noise was definitely from under the hood and on the passenger side (where all the a/c stuff lived, except for the compressor). randomidiot fucked around with this message at 08:00 on Apr 21, 2014 |
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Apr 21, 2014 07:54
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Weird, I got nothing then. Maybe a capillary or other tube was partially blocked in just the right way? Pressures equalizing could conceivably cause one to vibrate like a trumpet mouthpiece under the right circumstance.
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Apr 21, 2014 08:25
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That's basically what I suspected, but I don't know enough about a/c to say one way or the other.
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Apr 21, 2014 08:35
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Yeah it's really just a barely-educated guess on my part, Motronic is probably going to lay out exactly what was happening once he catches up on the thread.
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Apr 21, 2014 14:43
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It was probably whistling through the vanes of your beat rear end compressor as it was equalizing. Although I've never hear one quite as loud as you describe.
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Apr 21, 2014 15:22
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Update: Had the system recovered and flushed at a garage and I got the new parts installed! I couldn't get one drat screw off of the expansion valve so I'm letting it sit closed with a vacuum until morning to decide if I want to tackle that problem.  That little piece of poo poo black bolt. Head stripped when I gave it a good twist to break the corrosion. It's between the throttle body, and that low side line that snakes up and in the way of any kind of tool that would give me a chance of getting it out. Anyone have any good ideas? Old condenser    This was between condenser/radiator:  Old vs. New:  Oil from old:  Compressor Hole:  Compressor grinding: https://www.youtube.com/watch?v=_Ct5SNcRSwc The new compressor had oil in it already, so I just put about 1 ounce in the new condenser. Vacuumed for an hour and like I said I'll let it sit while I decide if I want to torture myself with bolt extraction. 
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Apr 25, 2014 02:00
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Seems like you've done OK. I like to drain new compressors to see just how much in in there. You really never know. But it should all work out.
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Apr 25, 2014 03:23
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Crosspostin' from the stupid question thread: I'm stumped by the aircon in my car. I've just had it checked and recharged because it had completely stopped blowing cold (600 grams low in a ~750 gram system), but it still doesn't always want to work properly. I can't really find the factor that determines it, but it seems to refuse to work when the engine is cold, mostly. And when it does work, it definitely works best when the car is moving. It seems to work best when I shut off the car and restart it while the engine is still warm. The heater works fine and there's plenty of airflow. All the flaps work fine, both direction and recirculation. It's definitely trying to cool, but it doesn't seem to be working as well as when I got the car. Lowest possible temperature, recirc on and full fan power should be cold enough to be uncomfortable, right? It definitely isn't in my car.
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Apr 28, 2014 22:21
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| # ? Apr 25, 2024 08:19 |
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Sounds like a compound problem. I'd start with telling us what kind of car it is. Then check that the condenser fan is turning on when the AC is switched on. This could explain the poor performance when you're going slowly. Then check that the compressor clutch is engaging. That could explain all of it. Lack of engagement could be wiring, control modules, low pressure switch, etc......things that could change their behavior when the are marginal based on how hot they are. Running pressures would be useful to know. Not working at low speeds could be RPM related if the compressor is spanked. Also, was anything repaired when this was recharged? Unless it's just been left to drain over 10-15 years and this is it's first recharge it sounds like you have a leak to address.
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Apr 28, 2014 22:41
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