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When checking pressures based on ambient temp, what point of the cycle are you reading high/low? I'm checking a car that peaks the high side at 170-175, and the low side dips to 25-30 at the peak before the compressor cycles off. Vent temps are nice and cold, it doesn't seem to be short cycling at all. This is at about 65-70 ambient, maybe 75 in the garage. I need to grab a new thermometer today, and I'm planning to recheck the system tomorrow.
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Jul 15, 2014 18:33
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| # ? May 31, 2024 12:02 |
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Do use the thermometer to check vent temps, you're looking for roughly 50F or colder, the closer to freezing the better; if it's very hot and/or muggy, ~30 degrees colder than ambient is sort of the minimum benchmark during initial startup, but it should still get down that low once the cabin is cooled off for a while. And you should be checking the pressures at their peaks, so right before the compressor cuts off.
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Jul 15, 2014 18:41
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That's what I thought it was, its been about 10 years since I've done AC work. Just by feel I think the vent temps are probably in the low 40's, but I just wanted to verify that before I called it done. The weather has decided to become unseasonably cool the last couple days (upper 60's in July, what?) but it was probably closer to 70-75 in the garage.
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Jul 15, 2014 19:00
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dyne posted:I replaced the TXV, vac'd the lines, and put in most of a 12oz can of r134a...and ended up with the same elevated high side pressure (300-350) and normalish low side (40-50). Some evaps and condensers don't flush well, if at all. Particularly parallel flow ones. But it's worth a shot. FogHelmut posted:2002 Ford Taurus I completely agree with IoC here. That mechanic doesn't know poo poo about AC past probably how to run the point and drool Robinair they keep in the back corner of the shop.
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Jul 15, 2014 19:24
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AC recently stopped working on my 97 Miata (it worked a couple of months ago when I bought it). I don't hear the AC clutch click when I turn on the AC or see the AC fan (I think that's what it is - adjacent to the engine fan, on the passenger side) turn ever. Any ideas?
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Jul 17, 2014 00:41
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Fuses are good and relays are getting power, although I haven't tested them for continuity yet because I'm looking for a wire I can sacrifice to be a test lead. Fan is not currently getting juice. I read that the fan does not engage if the pressure in the system is low enough so I'm going to take it in for a recharge tomorrow. I already have a bunch of scars on my right hand from frostbite and I don't want to repeat the experience.
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Jul 17, 2014 03:35
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So I watched the first few minutes of diagnosis on the Miata's AC and it looks like there's a leak on the front seal of the compressor. I asked the tech if the seal can be replaced/the compressor be rebuilt, he said no, whole thing needs to be replaced. Accurate? If so, is it something I can safely/relatively easily do myself if the system is evacuated? I'm still a mechanical noob and like I said, I'm very adverse to getting frostbite again (last time wasn't car related).
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Jul 18, 2014 19:15
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blk posted:So I watched the first few minutes of diagnosis on the Miata's AC and it looks like there's a leak on the front seal of the compressor. I asked the tech if the seal can be replaced/the compressor be rebuilt, he said no, whole thing needs to be replaced. Accurate? If so, is it something I can safely/relatively easily do myself if the system is evacuated? I'm still a mechanical noob and like I said, I'm very adverse to getting frostbite again (last time wasn't car related). Nobody really rebuilds compressors in the field. Or any other major automotive components. Those days are long gone. Why not just pay them to replace the thing? You obviously don't have the tools to do the job. You can't install the new receiver/drier unless you're ready to vac it RIGHT THEN, so they're still gonna have to go in there and do that.
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Jul 18, 2014 19:19
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Automotive vapor-compression refrigeration systems are pretty much the only system I won't touch. If I do it, I save a few bucks, maybe, depending on what I value my time at (probably not, anymore,) and I take a gamble on whether I really got the system vacuumed down properly, got everything installed properly on the first try, etc. If my mechanic does the work, he makes a little money off me, and he gives me a one year warranty parts/labor,
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Jul 18, 2014 20:09
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quote:You can't install the new receiver/drier unless you're ready to vac it RIGHT THEN, so they're still gonna have to go in there and do that. Got it, thanks.
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Jul 18, 2014 20:10
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Do I have to replace the drier if I replace the compressor? The shop told me if I replace the compressor ASAP I shouldn't need to, but how can I tell if its been exposed to air already from my leak - and won't it be exposed anyways when they replace the compressor? I'm not sure I follow their logic.
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Jul 19, 2014 00:41
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The drier gets replaced any time the system is opened. It's a one-shot dessicant.
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Jul 19, 2014 01:14
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blk posted:Do I have to replace the drier if I replace the compressor? The shop told me if I replace the compressor ASAP I shouldn't need to, but how can I tell if its been exposed to air already from my leak - and won't it be exposed anyways when they replace the compressor? I'm not sure I follow their logic. They are wrong. The desiccant in the dryer is used to remove the moisture from the system. Being a closed system, it gets used exactly once when you first bolt it up. This is why you don't put it on until last, and don't open the plugs on the dryer until you are ready to install it. And then you vac and fill immediately to reduce the amount of potential moisture in the system. Can you get away with it? Sure. On a beater that won't be around for too long I'll just vac the system for 45 minutes and call it good. But moisture and refrigerant make acid. Which eats the system from the inside out. So if you do it wrong, everything will seem A-OK for quite some time. AC will work, everything good. Until it finally eats through a line, and you realize everything else in the system is also ready to let loose 1 or 2 years down the road.
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Jul 19, 2014 01:21
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Got it, thanks. It looks like I'm going to RockAuto a refurb compressor for 250 and have the shop get me a drier; the cheapest compressor they could source was 650 and labor is 300.
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Jul 19, 2014 01:31
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I need some clarification relating to valve cores and caps. I vac'd, filled, and dyed my system two years ago. Performance was mediocre last season, and non-existent this season. Gauges show that I'm out of liquid refrigerant, but there's still enough of a charge to stay above the pressure switch's cut-off. None of the visible components are glowing under UV. When I filled the system though, some dye pooled in the service port and I could see a small bubble occasionally rise through it. I've heard a little leakage is expected, and that's what the service port cap is for. Is this true, or does the time-frame of refrigerant loss fit a faulty core? As cheap insurance, I was going to replace the caps and cores during this fill. I quickly found out when shopping that, while the service ports are standardized, the caps and cores are not. Is there an application guide somewhere that would tell me this information? I didn't see it specified in the FSM, and the closest I came in my search was a variety pack from Four Seasons (P/N 26783). Finally, do I need to buy a dedicated tool for removing the valve cores, or would one meant for a tire's valve fit?
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Jul 22, 2014 07:36
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Arbeit macht frei posted:I need some clarification relating to valve cores and caps. I vac'd, filled, and dyed my system two years ago. Performance was mediocre last season, and non-existent this season. Gauges show that I'm out of liquid refrigerant, but there's still enough of a charge to stay above the pressure switch's cut-off. None of the visible components are glowing under UV. When I filled the system though, some dye pooled in the service port and I could see a small bubble occasionally rise through it. I've heard a little leakage is expected, and that's what the service port cap is for. Is this true, or does the time-frame of refrigerant loss fit a faulty core? As cheap insurance, I was going to replace the caps and cores during this fill. I quickly found out when shopping that, while the service ports are standardized, the caps and cores are not. Is there an application guide somewhere that would tell me this information? I didn't see it specified in the FSM, and the closest I came in my search was a variety pack from Four Seasons (P/N 26783). Finally, do I need to buy a dedicated tool for removing the valve cores, or would one meant for a tire's valve fit? Sounds like valve core leakage to me. Sure, the service port cap is supposed to help with that, but if I saw one bubbling I'd change it. For the most part there are only a few kinds/sizes of cores. Here's the kit I have that contains all the kinds I've needed recently, save one (oddball high side on a diesel Suburban): http://www.amazon.com/Mastercool-91337-R-134a-Valve-Repair/dp/B000O823YO/ref=sr_1_1?ie=UTF8&qid=1406039848&sr=8-1&keywords=ac+valve+core Not suggesting you buy that kit, but you can see how few sizes there are and probably pull yours and identify them from that. If your tire valve tool is deep enough you should be able to get the cored out with it no problem, but they are bigger than a typical tire valve. Very small needle nose pliers work fine in a pinch.
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Jul 22, 2014 15:40
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I have a question about a 1984 Toyota Pickup with a 22r. My truck has factory A/C but the previous owner removed the A/C compressor tensioner pulley and the power steering pulley that bolts to the front of the crankshaft/harmonic balancer pulley. So the power steering belt goes right from the tensioner to the harmonic balancer on the crankshaft which causes the belt angle to be off slightly because the belt groove is for the A/C belt. I sourced the tensioner pulley and all the hardware but I cannot find the power steering pulley that bolts to the front of the crankshaft/harmonic balancer pulley. I'm not sure I'm calling it the correct part. This pulley has a large hole in the center that I believe goes over the crankshaft bolt and then 4 small holes around it. Anyone know a source for this part or what the proper name of it is? Once I get these parts I imagine I'll find out the compressor is shot. But I'll cross that bridge when I get to it.  The belt order in the pic from back to front is alternator/water pump, A/C then Power Steering. My truck is currently missing that front pulley and my P/S belt is on the middle pulley. The rear and middle portion of that harmonic balancer/crank pulley is 1 piece. Front pulley is held on by those 4 small bolts which thread into the double pulley behind it which is the part I need. Holy poo poo that's confusing to explain.
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Jul 25, 2014 04:49
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So, my brother's 1997 Jetta has some strange symptoms. The clutch for the compressor engages fine, as far as we can tell. But watching the pressure gauges suggests otherwise. The high side will climb up to over 350psi a few times then fall down back to 150 and then never go back above 200. The low side pressure dips when the high pressure climbs. The entire time the high side is faltering, the clutch is engaged, so we don't think it's a cutoff switch. What's going on?
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Aug 10, 2014 06:17
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EightBit posted:So, my brother's 1997 Jetta has some strange symptoms. The clutch for the compressor engages fine, as far as we can tell. But watching the pressure gauges suggests otherwise. The high side will climb up to over 350psi a few times then fall down back to 150 and then never go back above 200. The low side pressure dips when the high pressure climbs. The entire time the high side is faltering, the clutch is engaged, so we don't think it's a cutoff switch. Sounds like the compressor is hosed and puked pieces of itself throughout the system. My guess would be that opening up some lines would reveal black death everywhere. So you're looking at at least a compressor, TXV or cap tube (whatever that has), dryer and a flush.
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Aug 10, 2014 18:30
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Fortunately, we put some UV dye in it and found a decent mess on one of the lines to the condenser, so it will be opened up pretty soon. I'll check for black death when we do.
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Aug 13, 2014 02:45
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'97 Blazer, A/C blew hot when I bought it. Borrowed my brother's gauges, zero pressure. Went ahead and added two cans of 134a plus some dye, enjoyed cool-but-not-cold A/C for a day or so intending to pick up the final needed can of 134a on my next paycheck. Next day, A/C blows hot again, start checking with a UV lamp, to discover that the entire charge had puked itself right back out of the high pressure fill port. Is this going to be "pull old valve out, screw new one it and refill, enjoy cold air" easy, or am I looking at replacing the entire line the high side fill port sits on?
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Aug 15, 2014 03:32
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If it's coming out the schrader valve, it should indeed be that easy. You'll only need to replace the line if it's leaking out the base of the fitting. Keep in mind further leaks may appear on the high pressure side once the system is fully charged and starts getting up to the proper 220-250 psi range. Look especially closely at any fittings where an o-ring may have dried out, you don't know how long it's been empty.
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Aug 15, 2014 08:30
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Here's a new one. I know my car (06 Saturn Ion, same as a Chevy Cobalt for the a/c) is low on refrigerant. That said, every now and then, when I come to a stop, the air blows warm... and I get a very, very distinct refrigerant smell from the vents. The cooling capacity has been slowly deteriorating, and this has been happening more often. Today (low 90s), I was sweating in the car with the blower on 3 - normally "1" freezes me out of the car on hotter days, and I often have to run the heat with the a/c if it's below 85. I haven't put a set of gauges on it yet, but if this happened to you, what would be your first guess? Simply undercharged? Something leaking? On my next day off, I plan to get gauges and some R-134A with UV dye so I can figure out what's going on. If it matters, one of the service ports is missing its cap (I think it's the high side, but I'm not 100% - it's the one near the oil dipstick on the Ecotec 2.2). Also, since the cap has been missing for nearly 2 years, would it be a good idea to blow out the area around it with some compressed air before hooking up gauges?
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Aug 15, 2014 09:21
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some texas redneck posted:I haven't put a set of gauges on it yet, but if this happened to you, what would be your first guess? Leaking evap core. (hopefully not)
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Aug 15, 2014 12:29
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rndmnmbr posted:'97 Blazer, A/C blew hot when I bought it. Borrowed my brother's gauges, zero pressure. Went ahead and added two cans of 134a plus some dye, enjoyed cool-but-not-cold A/C for a day or so intending to pick up the final needed can of 134a on my next paycheck. Next day, A/C blows hot again, start checking with a UV lamp, to discover that the entire charge had puked itself right back out of the high pressure fill port. If the fill ports have had their plastic caps left off for a significant period of time and the valves are dirty, blast em out with compressed air and/or some brakleen and let it evaporate before replacing them. You don't want a pinch of dust and grit falling into the line while the valve is out.
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Aug 15, 2014 15:06
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some texas redneck posted:if this happened to you, what would be your first guess? I wouldn't guess. I'd shove some dye in there rather than trying to do an impossible exploratory exam on the one things that those symptoms might add up to (the evap core). But considering the fresh air intake is under/along the hood, it could be as simple as a valve core that's leaking and you're smelling it as it's drawn in from under the hood at a stop. In any case, dye is cheap and the right way to do it.
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Aug 15, 2014 15:43
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I think you nailed it already, actually. It crapped out during the hottest part of the day, and I smelled refrigerant. Popped the hood, saw a bit of bubbling around one of the valve cores (the one missing a cap) and heard a little hissing. It's looking like (and I'm REALLY hoping) it's a bad valve core. I'll get some gauges on payday and dump some UV-infused R134a in. I did notice it's only crapping out on the hottest part of the days, which leads me to think the low pressure cutout is saying "sup". Once it dropped below about 90 yesterday, it started working just fine. Above that and it gets flaky and lukewarm; above 95 and it's dead. So let's say I swap a valve core super quick - I know a vacuum is in order, but am I still replacing the receiver/dryer if I do this in, say, 30 seconds? I ask because the R/D are part of the condenser... which means pulling the radiator.. which means a lift... and a new condenser.
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Aug 17, 2014 11:10
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some texas redneck posted:So let's say I swap a valve core super quick - I know a vacuum is in order, but am I still replacing the receiver/dryer if I do this in, say, 30 seconds? I ask because the R/D are part of the condenser... which means pulling the radiator.. which means a lift... and a new condenser. They make a valve core tool that doesn't require emptying the system if you want to take that route. http://www.amazon.com/gp/aw/d/B000KITSMI?cache=0bc0dd17bb955b9a8e5a335c5eec4250&pi=SY200_QL40&qid=1408273974&sr=8-3#ref=mp_s_a_1_3 e: I speel gud
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Aug 17, 2014 12:16
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1999 M3, 79k miles, hardly ever drive the thing My AC doesn't blow cold and when it's on I get a supercharger-like noise that can be heard here. With AC off but the blower fan on I don't get that noise. Is there any hope that it's something other than a bad compressor? I guess it could be a combination of low refrigerant and a bad pulley/tensioner. I can do a bit of DIY although I've never touched the AC components. How should I attack this?
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Aug 17, 2014 16:36
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Easychair Bootson posted:1999 M3, 79k miles, hardly ever drive the thing I've got what sounds like the same thing on my 96 M3. Last summer I added refrigerant which helped for a little while but leaked out pretty quickly.
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Aug 17, 2014 16:47
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Easychair Bootson posted:1999 M3, 79k miles, hardly ever drive the thing Hard to tell from a recording, but it sounds like a whooped compressor. Adding more refrigerant/oil may quiet it down and make it work for a while, but chances are good you need a compressor AND a flush (because pieces of your compressor are probably in the system). This can happen for a lot of reasons, including but not limited to incorrect oil charge, contamination in the system (water or otherwise), a bad low pressure switch that is constantly running the compressor without proper oil and cooling, or past overcharging that was slugging the compressor.
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Aug 17, 2014 16:56
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Motronic posted:Hard to tell from a recording, but it sounds like a whooped compressor. Adding more refrigerant/oil may quiet it down and make it work for a while, but chances are good you need a compressor AND a flush (because pieces of your compressor are probably in the system). This can happen for a lot of reasons, including but not limited to incorrect oil charge, contamination in the system (water or otherwise), a bad low pressure switch that is constantly running the compressor without proper oil and cooling, or past overcharging that was slugging the compressor. edit: A can of refrigerant got the system up to 37 psi according to the cheapo gauge. Blows cold now. Compressor makes a new chattering noise at idle. We'll see how long the charge lasts. Easychair Bootson fucked around with this message at 17:47 on Aug 17, 2014 |
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Aug 17, 2014 17:07
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So you've ignored the first posts of this thread and used a quickie recharge kit rather than using a proper set of gauges so you might have some idea of what's going on. Good luck with that.
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Aug 17, 2014 23:06
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Do you have a recommended gauge set you use Motronic? I think my system might need some refrigerant.
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Aug 17, 2014 23:20
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Senior Funkenstien posted:Do you have a recommended gauge set you use Motronic? I think my system might need some refrigerant. If you want to spend $300 on gauges, sure. But the harbor freight ones work just fine at 1/4 of the price. They aren't going to take the same beating as a nicer set (mostly because of cheap rubber compounds) but if you don't do this for a living and keep them clean (you know, don't let the rubber sit for a year with dirty grease/oil on it) they should last you a long time.
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Aug 17, 2014 23:23
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Motronic posted:So you've ignored the first posts of this thread and used a quickie recharge kit rather than using a proper set of gauges so you might have some idea of what's going on. I guess I could go into the specifics of the circumstances that prohibit me from doing the job properly today, and why a can of refrigerant makes the most sense to me, but you'll just have to trust me. Or not. I do appreciate your earlier advice and the OP, though, which I'll be making use of when I fix my AC system later this year.
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Aug 17, 2014 23:45
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Argenteus posted:They make a valve core tool that doesn't require emptying the system if you want to take that route. That's a nice bit of kit, but $40 is kinda painful.  I have no problem emptying the system (I have a friend with a RobinAir, so it wouldn't be vented to atmosphere - and he could vacuum it + fill it exactly afterwards). I'm just wondering if the 30 seconds of being exposed while replacing the core will mean the need for new dryer. I would do it at his shop, with the machine ready to pull a vacuum.
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Aug 18, 2014 08:11
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some texas redneck posted:That's a nice bit of kit, but $40 is kinda painful. I don't know how expensive an accumulator or receiver/drier is for that car, but it wouldn't hurt to get one; that way you can just vacuum it, replace the valve & drier, vacuum again and recharge properly and know it's done right, without
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Aug 18, 2014 08:28
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The receiver/dryer is part of the condenser; non-replaceable without replacing the entire condenser, and the radiator + fan have to come out (and they only come out from below) to do so. GM took Ford lessons. It's north of $100, plus renting a lift for a couple of hours, and renting a lift means I won't have access to friend's RobinAir. The DIY shop MIGHT have a vacuum pump and recovery equipment, I'll have to check. If they do, I can do the actual recharge myself (friend with the RobinAir isn't even in the same county, much less the same city, as the DIY place - opposite directions).
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Aug 18, 2014 09:50
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This is one of those scenarios that $40 kit was pretty much made for.
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Aug 18, 2014 15:39
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