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Replacement AC compressor

Discussion in 'Tech Discussion' started by Ewhitaker0020, Jun 1, 2020.

  1. Ewhitaker0020

    Ewhitaker0020 Full Access Member

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    I'm attaching photos of my AC compressor and the sticker where it was retrofitted to 134a refrigerant. Do I need to know anything special to replace the compressor? Do I need to replace the drier and orifice tube as well? I can get a new 4 seasons kit on rockauto for around $180 that has these 3 parts.

    The compressor says with R4 compressor and without switch. My system was retrofitted in 1998 and worked AMAZING up until a week ago. It gets warm then cold and cycles like that. Also the compressor has gotten insanely loud. It's been loud for a while but ever since it started acting weird it's gotten even louder.

    I'm attaching several pictures.

    Also, one more question. While my ac was working the compressor would constantly cycle on and off. I mean like every 30 seconds. Now, I could see this being low refrigerant, but the thing is that the compressor cycled on and off even when the AC was turned off. I mean the HVAC setting was in the completely off position. The blower would turn off, but the compressor would continue to cycle. To stop this I would have to unplug the compressor.

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  2. 1987 GMC Jimmy

    1987 GMC Jimmy Automobile Hoarder

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    Have you owned the truck since new? If that’s the original compressor, and it did well with the retrofit for that long, that’s great. RIP to the Delphi/Harrison unit. They don’t make them like that anymore.

    For the compressor warranty to technically be valid, you’re supposed to do a new compressor, accumulator, o-tube, and flush. RockAuto will disclaim all this at checkout and even link you to the parts, but even if they didn’t care, these are all good things to do anyway. The accumulator has a desiccant perishable upon exposure to ambient air when the system is opened, the o-tube has a metal screen that can and does catch debris, and the flush liquid comes back brown out of the condenser, evaporator, and lines even on a system that didn’t have a catastrophic failure. I would do all of it. $180’s a good price, but you need to add the flush solution to that. You can rent the actual flush canister and manifold gauges from Autozone. You’ll need a decent air compressor to operate the flush kit.

    The job is nothing special, definitely one of the easier things to do if you have the tools, you just have to do it by the book and not improvise like most jobs allow you to do. I’d do a Ford blue rather than a GM white orifice tube, although both work fine, I’d recharge in the upper range, which is 80-85% of the original R12 system capacity, and pay close attention to how much/what kind of oil was pre-charged into the compressor. The compressor will have a sticker that says that, plus the literature will say it also. All R4s come from the same factory so there shouldn’t be variance in that respect, just a general rule. It should come with about 3 oz. of PAG 150, and you’ll have to add a few more. I believe it calls for 6-8 depending on the info you cite. I did 7 in my last R4 job. The instructions should also call to turn the compressor manually x amount of times when you install it, and really just follow anything they say to do.

    The new compressor manifold won’t mount directly to the hose block like your old compressor does (the suction and discharge ports are stepped rather than even) so the new one will come with a few manifold port seals of differing diameter/thickness and a paper that says which ones to use depending on port size, stepped vs. flat hose block, and presence/absence of pilots. The correct ones for this application should be included, but if they’re not, you’ll have to order separately after you get the compressor and are ready to install. I’ll attach that paper, and you’ll understand. Oh, and make sure you extract the old o-tube before you flush. If it gets stuck, you’ll either have to rent an extraction tool or you’ll have to heat the pipe with a torch and apply compressed air to the evaporator to blow it out. I’d wear eye protection if it comes to this because it blows out like a rocket smoking and everything.

    My answer to your last question is that it’s more than likely a bad speed select switch. You’ll have to pull the controller to replace.

    https://www.compressorworks.com/Upload/Four Seasons/documents/Tech Tips/English/4S 319-4S GM SEALING WASHERS - FOUR SEASONS.PDF
     
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  3. 75gmck25

    75gmck25 Full Access Member

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    Using ester oil was common for conversions in the past because you didn’t have to flush out all the old mineral oil used with R12. However, you are replacing the compressor and drier, and everything else is easy to flush, so PAG 150 or 100 is a better choice.

    I also used a Ford blue orifice. They used to be easy to find for about $3.00, but you might just get a dumb look from the parts guys these days when you tell them it’s for a GM vehicle.

    Bruce
     
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  4. Ewhitaker0020

    Ewhitaker0020 Full Access Member

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    Thanks for the in depth info! I will be taking the truck to q shop to have it vacuumed and charged after I replace the components. There's a local guy I like giving my business to as he's always done right by me.

    Do I have to replace the entire control unit to replace the speed select switch? It probably wouldn't be a bad idea honestly. Not everything on it works that great. I have a lot of trouble getting it to switch over to defrost and the heat/cold slider won't go all the way over to heat.
     
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  5. Ewhitaker0020

    Ewhitaker0020 Full Access Member

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    Where is the orifice tube located at on the vehicle? I remember watching an Eric the car guy video where he showed how to replace one on his dad's truck, but I can't remember.

    Is the blue Ford one just better? Do I need to find a specific ford one for a certain year? Or do I just ask for a blue Ford orifice tube?
     
  6. yevgenievich

    yevgenievich Full Access Member

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    Mid 90's ford trucks should pull up the blue orifice tube. It allows better cooling at idle. Located at inlet to the evap core. There is also orange that i used before but with different compressor and a few other changes
     
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  7. 1987 GMC Jimmy

    1987 GMC Jimmy Automobile Hoarder

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    No, the blower control switch pops off the face from the back, and it’s a separate thing. The mode switch is the same way, but the speed selector should be easier to replace.
     
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  8. Ewhitaker0020

    Ewhitaker0020 Full Access Member

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    My speed selector seems to work really good. I need to just go through and clean out the unit. Maybe that will help. My mode select and temp slider are giving me trouble. The temp slider seems to change the temp okay, but won't go all the way to heat, there's a resistance before it gets there.
     
  9. 1987 GMC Jimmy

    1987 GMC Jimmy Automobile Hoarder

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    Possibly. Either way, power is being applied to the clutch when it’s not supposed to be. If any connectors are melted or cracked or bare wires are touching, juice could be jumping across pins/wires when it’s not supposed to. It sounds like a long shot thing, but when those wires run close to the engine and disintegrate over time, especially the ones near the exhaust manifold, it happens, and it’s happened to me.

    You need to adjust that blend door cable to center the temp slider. You’ll need to pull the glove box, work the slider, watch the cable and arm move, and then you’ll see what you need to do.
     
    Last edited: Jun 3, 2020
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  10. yevgenievich

    yevgenievich Full Access Member

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    Temp slide operated a blend door in heat box, could either be sticking in the controls or at the actual blend door. Mode select operates vacuum selector and the ac switch if equipped
     
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  11. Charlie

    Charlie Mopar by Birth. Chevy by Choice.

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    Temp slider on mine was binding when I purchased it. I removed cluster bezel, removed climate control screws. Pulled out just enough to find the slider was dry and not wanting to move. Oiled slider mechanism, now works fine. Yours could be this also. Another thing to check.
     
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  12. Backfoot100

    Backfoot100 Full Access Member

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    You need to replace the rotary select switch for the AC. Its located on top of the temperature control assembly. Pretty easy to get to through the dash.
    That switch sounds like its been shorted out. That happened to mine. The AC compressor ran no matter what mode I put it in.
    The switch had a burn mark on it where it shorted out.
    Got a replacement from LMC for about $28 or $29.
    I would attach the parts diagram but I'm not at my PC.
     
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  13. 80BrownK10

    80BrownK10 Full Access Member

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    It's in the lower tube coming out of the AC box that goes to the evaporator.

    And orfice tubes are colored and specific to brand. A does blue Tobe is a Ford blue tube. There is white ones red ones etc but there for applications and all the same size as far as I remember. It fits many age ranges for decades.
     
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