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Misbehaving clutch cycling switch

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  • huntindog
    replied
    No. It is a standard CCOT affair.

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  • Cornbinder89
    replied
    Click image for larger version

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ID:	261 Does it have a pilot operated Absolute valve?

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  • huntindog
    replied
    Originally posted by Cornbinder89 View Post
    Click image for larger version

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    That looks similar to how it was.

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  • huntindog
    replied
    Originally posted by Cornbinder89 View Post
    From what I can remember from back then, they had a VIR (valves in receiver) which has a large accumulator looking thing, It took a replaceable desiccant "bag" with the valves in the removable top portion. A cycling pressure switch I don't think would work with that system. There are a million temp switches with a probe that can be placed in the fins. There are both fixed and adjustable types. Click image for larger version

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    That I do not have.

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  • Cornbinder89
    replied
    Click image for larger version

Name:	MEI 1331.png
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ID:	257

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  • Cornbinder89
    replied
    As far as thermostatic switches Heavyer GM's use a MEI 1331 which is a 24" capillary tube switch fixed 34-38 deg or about a 5 deg off to on temp.

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  • Cornbinder89
    replied
    From what I can remember from back then, they had a VIR (valves in receiver) which has a large accumulator looking thing, It took a replaceable desiccant "bag" with the valves in the removable top portion. A cycling pressure switch I don't think would work with that system. There are a million temp switches with a probe that can be placed in the fins. There are both fixed and adjustable types. Click image for larger version

Name:	GM VIR.png
Views:	14
Size:	21.7 KB
ID:	254

    Leave a comment:


  • Tom Greenleaf
    replied
    Originally posted by huntindog View Post

    You are correct. It originally had a temperture probe into the evaporator. Those did not seem to be all that reliable, and now seem to be unavailable. So I installed the clutch cycling switch instead into the accumulator. Like I said, it was new along with everything else about 6 weeks ago. But it never worked.

    In am figuring that it is trying to start working now. Probably been sitting on the shelf for years and got stuck. (R12 switch)Since under my present conditions, it really isn't critical, I came up with the jumping it idea. Perhaps with some more of it trying, it may free itself up. And I can always manually shut the compressor off with my switch, if I encounter super low vent temps.

    One thing for sure, i do not like the rapid on/off that it is showing me now at low temps. That can't be good for the clutch.

    But if I leave it screwed in to the accumulator with no wires attached to it, that may just allow it to heal itself. Of course I want it to be working properly when it will be needed more than it is presently.

    It would be warrantable, but I figure the replacement may be in the same condition.
    ! I missed that comment somewhere! Seriously I didn't think any were non CCOT only set ups. Accumulator mounted switch with the low port on the same unit.

    If somehow this is not close to OE intentions not sure what to say now. It could drop low pressure but don't understand how if the two ideas were fighting with each other would behave as I wouldn't do that unless somehow no choice.

    Long time ago and didn't think "Chevy" ever used a "thermistor" is I think was it's called sensing temp not pressure - Cadillacs did I think some Buicks used a fuse but blown was blown you got another if not power to clutch??

    Not sure but temps you get are good. The rapid cycling can't be good for it if too often.

    I have to plead "IDK" what you can get for this for funky parts if so and easily?


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  • huntindog
    replied
    Originally posted by Cornbinder89 View Post
    I think he has that and a pilot light, he said he added that when he towed a lot with the Blazer
    You are correct. So I can control the clutch manually.

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  • huntindog
    replied
    Originally posted by Cornbinder89 View Post
    So... is this an orifice tube system? I would have thought it was a VIR or Tx system with a frost switch, Somewhere I have a '73 Chevy truck manual but can't lay my hands on it right now. Anyway you cut it, there is supposed to be a difference in cut-out cut-in temps/pressures to prevent short cycling. IS this a temp operated switch? I would think so given the year we are talking. Calling it a "clutch cycling switch" is confusing me, makes me think it is a pressure operated switch like in a CCOT system.
    You are correct. It originally had a temperture probe into the evaporator. Those did not seem to be all that reliable, and now seem to be unavailable. So I installed the clutch cycling switch instead into the accumulator. Like I said, it was new along with everything else about 6 weeks ago. But it never worked.

    In am figuring that it is trying to start working now. Probably been sitting on the shelf for years and got stuck. (R12 switch)Since under my present conditions, it really isn't critical, I came up with the jumping it idea. Perhaps with some more of it trying, it may free itself up. And I can always manually shut the compressor off with my switch, if I encounter super low vent temps.

    One thing for sure, i do not like the rapid on/off that it is showing me now at low temps. That can't be good for the clutch.

    But if I leave it screwed in to the accumulator with no wires attached to it, that may just allow it to heal itself. Of course I want it to be working properly when it will be needed more than it is presently.

    It would be warrantable, but I figure the replacement may be in the same condition.

    Leave a comment:


  • Tom Greenleaf
    replied
    Heard of the rather toasty temps in your area! Hey - great to have the cool and probably get away with it as air pretty dry there - Phoenix. Verify that vent temp with another thermometer. You said 37.8 later at 88F ambient would be plain excellent but really shouldn't stay even there.

    Do you have the old switch? Check - it's old enough I can't remember but should screw on with just a rubber O ring. The old one would show that inside it could to just that so you don't lose your charge the reason being it's probably adjustable! I could be wrong but think tightening will raise cut out pressure. Just go 1/4 turn no more at a time if you try that.

    Watch out! IF there's not Schrader it will blow out all refrigerant you don't want nor get hurt. It would hiss even if you remove them fast just a very short time then quit you know you are good to check while charged.

    Check real temp of air coming in thru grille not just that forecast temp. Road surface could be a LOT hotter so this is exceptionally cold output if higher air temp than you thought.

    BTW - A couple times put the Ford from the 80s common larger mushroom cut out switch with plug if used so be it either spliced in or lease OE and make up good wire just spade terminals definitely adjust. There a risk in doing that it could leak so check.

    Cycling clutch? Check the air gap and set to close if not. About .020 is a standard or folks would say a folded standard business card paper would be snug.

    Trivia: If clutches friction surface is hot from cycling it's losing magnetic force to pull it in or keep it engage may cool and be more magnetic! Funky but the hotter the metal the less magnetic! A maybe to rule out and might need checking function of the clutch of its coil,

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  • Cornbinder89
    replied
    I think he has that and a pilot light, he said he added that when he towed a lot with the Blazer

    Leave a comment:


  • Cusser
    replied
    Ever think of installing a dash-mounted toggle switch to turn the compressor off and on? If your evaporator temperature is really low like 32F, then on days when we do have some humidity, you could get ice freeze up on your evaporator.

    Leave a comment:


  • Cornbinder89
    replied
    So... is this an orifice tube system? I would have thought it was a VIR or Tx system with a frost switch, Somewhere I have a '73 Chevy truck manual but can't lay my hands on it right now. Anyway you cut it, there is supposed to be a difference in cut-out cut-in temps/pressures to prevent short cycling. IS this a temp operated switch? I would think so given the year we are talking. Calling it a "clutch cycling switch" is confusing me, makes me think it is a pressure operated switch like in a CCOT system.

    Leave a comment:

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