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ac not cycling ?


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jimbo-jim
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Jul 11, 2019, 4:03 PM

Post #1 of 21 (607 views)
ac not cycling ? Sign In

2000 Silverado 2500 6.0
guy's I have replaced my compressor, accumulator, orifice tube, both switchs hi and low I also replaced the cycle switch on the back of the compressor. I have missed something what is it ?


Hammer Time
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Jul 11, 2019, 4:45 PM

Post #2 of 21 (600 views)
Re: ac not cycling ? Sign In

Why is that a problem?

Cycling is related to pressures at the time and will only cycle when the pressure drops low enough. On a hot day, on high blower, the pressure may never go low enough to cycle.



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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.



Tom Greenleaf
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Jul 11, 2019, 4:46 PM

Post #3 of 21 (598 views)
Re: ac not cycling ? Sign In

First question is what was wrong that made you do that much?
Next is by "cycling" do you mean it wont engage or is engaging but not shutting down now and then??
I didn't see condenser in the parts tossed when a system goes bad it's a filter is wrecked each time is sustains a failure could easily spike a quick high pressure and not allow compressor to come on.


Of all things this too not just smaller vehicles you must charge with a full vacuum, well held and know the exact weight of charge get that within say 5% would behave.
What did you do for oil charge prior to putting it together? If nothing it's burning up or too late already. Compressors are an unknown you spin those with oil on the bench many times first or risk instant burn up if dry. You count/measure how much oil came out of old parts, accumulator even drill a hole and heat it up to get almost all out.
What you do to fix a system that doesn't work is first do a lot of diagnosing what the source problem is then proceed.


It's unforgiving of mistakes unfortunately one wrong move and let it run wrecks new parts and easily make you start over.


Oil and condenser not mentioned nor what was wrong so this is just asking time what and why you did what you did mostly,


T



jimbo-jim
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Jul 11, 2019, 5:54 PM

Post #4 of 21 (590 views)
Re: ac not cycling ? Sign In

I replaced the compressor because the clutch was bad and when I got the compressor out I could tell someone had already been in it so I just replaced it . I put 6.5 oz. of pag 46 I allowed for oil in condenser that's what manu. called for. The condenser was flushed also it is engaging I can jump it


(This post was edited by jimbo-jim on Jul 11, 2019, 5:57 PM)


Tom Greenleaf
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Jul 12, 2019, 2:13 AM

Post #5 of 21 (572 views)
Re: ac not cycling ? Sign In

? Jimbo - trying to read thru this where this is at: Compressor DOES NOT engage unless jumped - right? Just words used are mixing me up. "Cycling" is what this system is set up to do when called for not necessarily just come on and off just randomly. Default is it wouldn't engage.
Watch out what you jump or fry computer controls.
Watch out also for listed or suggested oil charge amounts. System could have oil in assorted places holds 8oz when known empty 6.5 for a condenser is just someone's guess - always a guess. Even if you thought it needed that much you would add it upstream not into condenser the compressor is what needs lube nothing else. It circulates the oil during operation.
Condenser can't be flushed not the point right now it's probably junk if a solvent used how did you get that out?


All this over a clutch! Was it ever vacuumed out and then charge weighed in or what?
How about this for a finish to this: Take it to shop and have it vacuumed out and charged by weight tell them you added 6.5 oz of oil. Then it has a new starting point. I just suspect this was never prepared to be ready for that final step. If that's not done properly all info is lost again.
No pressures ever listed by you and you or someone tried to flush a condenser are strong clues you should seek some help but say what you did so far so if it can be saved it has a better chance.


Without specific info on what you did I can't do more than guess it's been messed with, jumped who knows where and no mention of vacuum first can't do this over the web like this.


Beware of video junk and products, tools and info that may tell you how easy and basic it is. It isn't at all rather is a whole course of study and requires more tools and equipment that almost anyone would buy to do this stuff isn't worth it for most,


Tom



Hammer Time
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Jul 12, 2019, 3:33 AM

Post #6 of 21 (568 views)
Re: ac not cycling ? Sign In

These condensers cannot be flushed.

These are designed as a "bypass" type design. They have a single chamber feeding all rows. It can be up to 90% totally blocked and you can still blow through it. The old "serpentine" design is no longer used. That is the only type that could be successfully flushed out.

Condensers HAVE to be replaced when a compressor has a catastrophic failure in today's vehicles.



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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.



Sidom
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Jul 12, 2019, 9:08 AM

Post #7 of 21 (555 views)
Re: ac not cycling ? Sign In

When you say "not cycling"....
Do you mean the comp is running continuously without cycling or isn't coming on at all?


jimbo-jim
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Jul 13, 2019, 6:36 PM

Post #8 of 21 (528 views)
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no it will not come on when I turn I the ac on it only blows warm air


Hammer Time
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Jul 14, 2019, 3:57 AM

Post #9 of 21 (511 views)
Re: ac not cycling ? Sign In

Well, that's entirely different from your original post. Cycling means temporarily shutting off until the pressures recover, usually 5 or 10 seconds.

You're going to have to follow a wiring diagram to determine where the issue is.

Here is the diagram





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jimbo-jim
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Jul 14, 2019, 7:14 AM

Post #10 of 21 (492 views)
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thanks for that. low pressure is 50- hi- side 200- but the compressor will not kick on. I will ckeck wiring


Hammer Time
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Jul 14, 2019, 7:21 AM

Post #11 of 21 (488 views)
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Now that is just a ridiculous statement.

That is totally impossible without the compressor running. You're not going to like this but you need to walk away from this and bring it to a competent AC technician. If you can't tell when a compressor is running and when it isn't, you have no chance of diagnosing this problem.



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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.



jimbo-jim
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Jul 14, 2019, 5:49 PM

Post #12 of 21 (478 views)
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if you read the original post I said I could jump it the compressor but it would not kick on by itself cheez


Tom Greenleaf
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Jul 14, 2019, 11:37 PM

Post #13 of 21 (463 views)
Re: ac not cycling ? Sign In

That's not a cycle switch on compressor sport. It probably came with a plug you put the heat sensitive plug from old compressor in there. It shuts down system if pressure is too high or if hot. Other set ups or use it would blow everything out if too much pressure this shut down the power.
A/C isn't DIY friendly. Cycling is not a term for "engaged" as in it's compressing rather the name for a system designed to come on and shut off as pressures and temps dictate. CCOT = Clutch Cycling Orifice Tube system vs using an expansion or "X" valve meters in refrigerant as needed this is NOT that type, Tom



jimbo-jim
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Jul 15, 2019, 5:26 AM

Post #14 of 21 (455 views)
Re: ac not cycling ? Sign In

as in first post I stated I replaced all of the switchs even the one the back of compressor. im sure I will figure it out


jimbo-jim
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Jul 15, 2019, 7:34 AM

Post #15 of 21 (437 views)
Re: ac not cycling ? Sign In

can you give me the power values for the wires the dark green and the light green also the dark blue ?


Hammer Time
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Jul 15, 2019, 7:51 AM

Post #16 of 21 (431 views)
Re: ac not cycling ? Sign In

Everything you need to know to solve this problem is in the wiring diagram already with the exception of the AC request which you need a scan tool for.



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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.



jimbo-jim
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Jul 15, 2019, 8:25 AM

Post #17 of 21 (424 views)
Re: ac not cycling ? Sign In

I've got the pic hammer but I would like to know how much juice it's getting. since i'm not as smart as you.


Hammer Time
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Jul 15, 2019, 8:29 AM

Post #18 of 21 (422 views)
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That's my point here. The diagram is self explanatory. There is no voltage. These are ground signal circuits.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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.



Sidom
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Jul 15, 2019, 11:18 AM

Post #19 of 21 (417 views)
Re: ac not cycling ? Sign In

Ok, I believe this one is too new BUT on some of the chevys, if there is an a/c trouble code in the HVAC module this will disable the a/c

Disconnect the battery, pump the brks a bunch of times, turn the lights on and back off and then hook battery back up. If the a/c still doesn't work, get a voltmeter and check power at the comp clutch connector for 12v.

If there is no power, go to the fuse box and pull the a/c relay, with the key on & a/c off 2 of the relay terminals (in the box) should have 12 v, 1 terminal should show a good ground and the 4th terminal should show nothing on it... Now turn the a/c on and the 4 terminal should now show a good ground..... If it doesn't then the PCM, for whatever reason, isn't turning on the a/c. A scan tool would make it a lot easier to find the problem but it isn't impossible to find without on....just a huge PITA.

Do this other stuff 1st and let us know what you find out....


(This post was edited by Sidom on Jul 15, 2019, 11:19 AM)


jimbo-jim
User

Jul 19, 2019, 3:21 PM

Post #20 of 21 (382 views)
Re: ac not cycling ? Sign In

thanks for that info . I went through the things you said to try with no luck . also I checked the power at relay everything checked out as you said except when I turned the a/c on I did not have a ground on the 4th wire. now I can jump a wire from the compressor to the switch on the control module and the a/c comes on and off with the switch could there be a wire broke between console and relay ?


Sidom
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Jul 19, 2019, 6:33 PM

Post #21 of 21 (375 views)
Re: ac not cycling ? Sign In

That 4th terminal is the one the PCM uses to turn on the a/c (ground the relay).
While it is possible to have a bad wire between the PCM and relay it is more likely there is something causing the comp not to turn on the a/c.
There is a list the comp looks at before turning on the a/c, 1st then engine can't be overheating, it has to be charging, it can't be at wide open throttle, then it looks at the a/c pressures, the low side can't be too low, the high side can't be too, high, those are just the few I can remember off the top of my head.
I had a bad battery kill an a/c once. The truck started off at 14.4v and you could watch the voltage slowly drop as the engine ran, as soon as it hit 12.8 the a/c would kick out and wouldn't come back on until the truck sat for at least an hour.

This is where a scan too is very helpful.

You can check the wire for a bad connection. If HT will post you a pin out of the PCM connectors (I believe it's in C1???) you can find the terminal that ground the a/c relay, turn on the a/c and check that terminal, backprobing the connector would best, but if you have to, pierce the wire an inch off the connector, just be sure to seal it with liquid tape when you are done, and see if you get a ground signal. If you do, you have a bad/broken wire between the PCM and fuse box, if there is no ground signal, the the PCM isn't turning on the a/c for some reason


EDIT.... I just zoomed HT's diagram.... It's connector C2, pin #43.... Dammit... almost guessed right


(This post was edited by Sidom on Jul 19, 2019, 6:40 PM)






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