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a/c compressor keeps cycling in & out - help?!?!?!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by creampuff90k5, Jun 29, 2003.

  1. creampuff90k5

    creampuff90k5 1/2 ton status

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    Well, today was the day to add my usual two cans or so 134a to the Blazer for summer. I know there's a small leak in the system, but it takes five or six months to get to the point where the A/C is no longer cool and by then, being in New Jersey, I don't need it any more until the next summer.

    So the problem is that the system won't even take part of the first can because the compressor keeps cycling in and out. Like it engages for about two or three seconds, then disengages for five to ten seconds, and so on and so on...

    So what's the deal?? Would like to get this fixed ASAP 'cause I might not have the time to work on the truck for a while after today. Thanks!

    P.S. Was converted from R12 to 134a a number of years ago, so that's not part of the issue.
     
  2. Confedneck

    Confedneck 3/4 ton status

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    bad clutch? bad cycling switch? ?? i have almost no a/c background.. but id start by checking the clearances on the clutch on the compressor...good luck
     
  3. rcpilot

    rcpilot 1/2 ton status

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    Try bypassing the cycle switch... this will run the compressor non stop... then you will be able to get the required amount of 134 into the system...if the system is low then the switch cycles the comp. rapidilly until there's enough 134. Are you using a guage set to check pressures?
     
  4. creampuff90k5

    creampuff90k5 1/2 ton status

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    rcpilot, how exactly do I bypass this cycle switch? Excessively low pressure is kind of what I expected was causing the problem... I have never used any gauges when filling. Like I said in my initial post, adding one or sometimes two cans usually turns the air quite cold and it stays that way for several months.
     
  5. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Turn the A/C on Max, this will keep the compressor on continously. If it's on NORM, the compressor will cycle on and off.
     
  6. jimmyjack

    jimmyjack 1/2 ton status

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    I'm not sure what it's called but up near the fire wall on the passenger side theres a black cylinder. I think it's the condenser, anyways it'll have a plug with two wires. Pull the plug and stick a paper clip in there. It'll full the compressor while you fill it up
     
  7. HarryH3

    HarryH3 1 ton status Author

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    What he's tryin' to tell ya about is the low pressure cutoff switch. It prevents the compressor from running if the pressure in the system is too low, so that the compressor won't be damaged. /forums/images/graemlins/cool.gif The switch is screwed into the low pressure line coming out of the receiver/dryer. That's the silver can next to the big black plastic box on the firewall, which contains the evaporator. There will be 2 wires going to a connector that plugs into the switch. Unplug that connector and bend a piece of wire so that you can insert it into the plug and short the 2 wires together. Now start the truck, turn on the a/c, and start charging up the system. /forums/images/graemlins/thumb.gif
     
  8. jimmyjack

    jimmyjack 1/2 ton status

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    Yeh, that thing........ that he said. 'cept mines black. I was cooking dinner so my thought weren't all there. Good luck. Keep us informed
     
  9. HarryH3

    HarryH3 1 ton status Author

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    [ QUOTE ]
    'cept mines black

    [/ QUOTE ]
    Somewhere along the way they started wrapping them in black insulating foam so that there isn't so much heat absorbed from the engine bay. Our '94 is set up like that. Hmm, perhaps that wrap is another good thing to add to my shopping list for the next trip to the Pick-n-Pull. /forums/images/graemlins/cool.gif
     
  10. creampuff90k5

    creampuff90k5 1/2 ton status

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    Re: a/c compressor keeps cycling in & out - Update

    Okay, bypassed the low pressure cuoff switch and the compressor engaged immediately, so I started adding the r134a. Problem is, it doesn't seem to be flowing out of the can at all! Is it possible that the valve and short length of hose I'm using are clogged or somehow defective?? I think the valve may be messed up because you can open it up while sill attached to the can and nothing comes out, but when I attempt to unscrew the valve off of the can, 134a starts to leak and spurt everywhere. And yes, I'm using the valve correctly - have done this many times in the past.

    Probably answered my own question and shoud get a new hose, but I just wanted to see if anybody else had this happen 'cause I'm going freakin' broke wasting $5 cans of refrigerant!!
     
  11. rcpilot

    rcpilot 1/2 ton status

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    Re: a/c compressor keeps cycling in & out - Update

    I'm not totally familiar with 134 but with R-12 I found out contrary to the directions I DID have to hold the can upside down inorder to get the freon to flow... this alows the liquid to flow into the system... holding it upright only allows the gas that is being vaporized in the can to flow... you wnat the liquid to flow...once in thte system it will turn into gas and pressurize.
     
  12. JustHorsinArownd

    JustHorsinArownd Registered Member

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    Re: a/c compressor keeps cycling in & out - Update

    I shake the can the entire time I'm adding the freon. I forget where I was told that but it seems to do the trick in our Suburban. Good luck!!

    Allan
     
  13. Dale fan

    Dale fan 1/2 ton status

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    Re: a/c compressor keeps cycling in & out - Update

    Yeah try shaking the can while holding it upside down. Wish my freon, R12, was only $5 a can. /forums/images/graemlins/angryfire.gif
     
  14. creampuff90k5

    creampuff90k5 1/2 ton status

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    Re: a/c compressor keeps cycling in & out - Update

    Thanks for the tips, but I already tried the can both rightside up and upside down and also shook it, but still wasn't working. I truly believe the problem is the hose apparatus b/c further inspection last night revealed that the little gasket or o-ring that mates with the can was chewed up and fragmented pretty badly. I'll pick up a new one today and give it one more go hopefully tonight.
     
  15. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    Re: a/c compressor keeps cycling in & out - Update

    Since you're not using a gauge maybe you put too much pressure in the system? There is a low and high pressure switch on the A/C and both turn the compressor off. I'm just guessing that maybe the reason it isn't taking any more refrigerant is because it's full. /forums/images/graemlins/eek.gif that would be bad! But since nobody else has mentioned this, unless I forgot to read that post, maybe that's not your problem.
     

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