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A/C Clutch Does Not Engage
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thumb
Novice
Jun 20, 2018, 12:38 PM
Post #1 of 12
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A/C Clutch Does Not Engage
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I read some of the posts about this same subject and tried all the fixes that I could to no avail.
I have a 1989 Chevy Astro van with a 4.6 V6 and it has 336K miles but the A/C was replaced about 2 years ago. Here's the info I have.
A/C was working fine but I had a clutch that was rattling like crazy so I installed a new one with a .030 gap. Now the clutch does not engage. I have 12v at the coil connector and when I turn the AC on, the engine revs up like the AC is working but the clutch just sits there. I know you're not suppose to do this but I did jump the low pressure relay just for a split second just to see if that would engage the clutch and it did not. So I tested the coil itself and between the 2 contacts I get 0 ohms with meter set on 2K and between either contact and ground to compressor I get 0 ohms also. Reading on these measurements it says if there is no resistance between the two contacts that I have an open and need to replace the coil/pulley. This is all fine except I measured the brand new coil that I got with the clutch set and it gives me the same readings, both 0 ohms between contacts or either contact to ground so I'm stumped on what to do next.
(This post was edited by thumb on Jun 20, 2018, 12:41 PM)
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Hammer Time
Ultimate Carjunky
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Jun 20, 2018, 1:03 PM
Post #2 of 12
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Re: A/C Clutch Does Not Engage
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First thing is you have a 4.3, not a 4.6.
Second thing is trying to replace just a clutch in this situation is a stupid move. The clutch likely went because there are other issues in the system increasing the pressure on the clutch. You probably just wasted your money doing that and I'm betting you will waste some more trying to resolve this yourself. AC repairs are not as simple as everybody tries to believe it is. There are numerous other factors to be considered when diagnosing this issue and it's going to take a lot of refrigeration experience to resolve it correctly. With that many miles, bubble gum just isn't going to work.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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thumb
Novice
Jun 20, 2018, 1:15 PM
Post #3 of 12
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Re: A/C Clutch Does Not Engage
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Thanks for answering my question and not treating me like an idiot. Now can someone jump in and tell me why if I have o ohms on bot contacts why they say its an open which in my experience 0 ohms means the two contacts are shorted. Plus I stated that everything else checks out voltage wise and that the circuitry is indeed working, just the coil is not activating the magnet to draw the clutch in.
The reason I did not install the coil/pulley is that I did not have a puller for that but I will get one and redo the whole thing again. It's not rocket science here but then I'm not as smart as someone here.
Goodbye
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Hammer Time
Ultimate Carjunky
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Jun 20, 2018, 1:29 PM
Post #4 of 12
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Re: A/C Clutch Does Not Engage
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If you don't want to be treated like an idiot, stop acting like one.
You're not measuring any resistance on the coil because you are using the wrong scale on the meter.
The manufacturer doesn't provide a resistance spec for that coil but that 2K scale likely doesn't read low enough.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
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Jun 20, 2018, 2:16 PM
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Re: A/C Clutch Does Not Engage
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OP, I don't know of a clutch air gap that should be that large is about where they wont pull in. .020 more like it. Ohms reading ZERO you are measuring incorrectly or it's wide open not accepting power and ground at all is the coil not just the part if you could find it with the bearing.
Anywho - most would be about 3.5 to 4.5 still doesn't mean it will work just a test. I really don't know now what's easily available easily if that's all it was?
That bearing if wobbling I'm surprised you could do just a clutch at all and no damage beyond that doesn't explain why is lasted at all?
T
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thumb
Novice
Jun 20, 2018, 2:35 PM
Post #6 of 12
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Re: A/C Clutch Does Not Engage
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Thank you Tom for your reply, much more respectable. The gap number I quoted was from a GM youtube guy who said that GM's are usually .025 to .035 and .030 was the average so I went with that. I did close it up to .020 and still no luck. I was reading about 2 to 3 ohms but thought that was just an error factor in my meter so I guess that's good then or close. The pulley itself seems to be in great shape with no wobble and no sounds coming from it when the belt is off but then there is no load on it. Like I mentioned, only the clutch was making the racket when engaged and if you turned the AC off the noise would stop but you could take your finger and move the clutch back and forth very easily. I will be removing everything and installing the whole kit as soon as I get a puller since it seems that everything else I tested came out the way it's suppose to be hopefully it will work.
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Hammer Time
Ultimate Carjunky
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Jun 20, 2018, 2:52 PM
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Re: A/C Clutch Does Not Engage
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Did you put the ground wire back on the alternator bracket?
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
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Jun 20, 2018, 3:05 PM
Post #8 of 12
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Re: A/C Clutch Does Not Engage
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Please thumb - just works to be nice to anyone. This is 100% volunteering our time for strangers. I don't know which compressor this is yet to even try to look it up. Generally if close to even real close but doesn't rub at all it's easier on it.
If it's been cycling a lot and hot where you are that's a reason to have assorted issues going on and maybe had the clutch almost glowing hot too much cycling can barely think of a place in US that's been just warm rather a huge area smoking hot!
System just works that much harder and clutch may have been slipping got super hot then metal loses ability to be magnetic. Try if you want to pick up a glowing nail or something AYOR it wont pick up.
IDK - I hear these going noisy and all depending can usually put just a bearing in for dirt cheap all depends what you find. That's not it right now so if now you are reading ohms at all tap on the outer plate and see if it snaps till next cycle it might?
Exact specs - I'd never find don't know what compressor is in the thing now some folks might have changed it for another type totally or more than once at the age and miles.
Tap on it see what happens and take a static pressure reading at least there's a chart in the "Charging Procedures" up top locked if you can find temp of engine are accurately that should be spot on if lower you have more troubles. Things, this included fail in temp extremes some with little warning this had one if working it hard,
T
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Hammer Time
Ultimate Carjunky
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Jun 20, 2018, 3:45 PM
Post #9 of 12
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Re: A/C Clutch Does Not Engage
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I'm betting he didn't hook up the ground.
Even if he gets it to engage, he's probably going to see a compressor failure in the near future.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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thumb
Novice
Jun 20, 2018, 6:19 PM
Post #10 of 12
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Re: A/C Clutch Does Not Engage
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Never removed the ground wire Hammertime, it's got it's own ground on the two wire connector unless there's a ground wire in the back of the compressor which I don't know because I didn't remove that, just the clutch. As for what kind it is, the shop put a whole new AC system in a few years ago but here's a pic of it.
Here's something I tried, turning on the ignition but not starting the engine and turn the A/C on, I can push on the clutch and it does snap onto the pulley. I'm going to try and move the clutch in a lot closer and see if that helps.
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Hammer Time
Ultimate Carjunky
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Jun 20, 2018, 6:26 PM
Post #11 of 12
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Re: A/C Clutch Does Not Engage
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Yes, there is a 2 wire connector and the other end of one of those wires is bolted to the bracket.
That is an R-4 compressor and the spec is
Clutch Plate to Rotor Gap .................... 0.5-1.0 mm (0.02-0.04 in.)
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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thumb
Novice
Jun 20, 2018, 8:06 PM
Post #12 of 12
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Re: A/C Clutch Does Not Engage
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Good news, I got it to engage at .015" and the AC is working great. I still want to install the pulley though because there is still a little bit of noise but not 1/3 as bad as it was.
Thanks for all your input.
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