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a/c clutch wont engage

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  • a/c clutch wont engage

    I recently put a new 4.6v8 in my 2004 Dodge Ram 1500 now the A/C doesn't work. I assume I've got a leak and I don't want to jump the low freon switch to get the clutch to engage due to compressor damage. I hooked up my gauges and turned the air and fan on with the key on, and it only took a little bit of the refrigerant. With both gauges hooked up, it read 95 on the low side and 100 on the high side. Any idea how I can get it to take some of the freon without jumping the switch? Thanks.

  • #2
    Welcome. Don't touch the refrigerant side of this you have no way to know how much refrigerant is in it except adequate "static" pressure adding any now you really have no clue how much is in there and should take it all out, weigh what comes out and put back the know listed amount then let some testing begin.

    Before getting too involved who did this engine swap? That is "invasive" work of course everything unplugged and refrigerant removed to do that no doubt may or may not have been put back and ever tested from that work. So invasive plus just no knowing what sensors (all over that job) were swapped over and what item require the "computer" to re-acquaint" itself to this and it runs everything or can stop anything avoid jumping or blow that if not a problem already.

    How recent and who? Take it back and get a full printout of all codes present even if any check engine warning isn't on the "dealer's side" doesn't light it or set things all over now should have been done and set for the engine swap or all bets are off.

    Do you have a listing that's accurate of just what was done? Was it charged at all with refrigerant or could that be done (doubt it) without touching the refrigerant at all?

    Defaults are going to be item don't work - not allow to a list of things to work unless all things sensed are "ready" to allow it,

    MetroWest, Boston


    • #3
      95/100 sound high for this time of year, what is the ambient temp when those reading were taken?


      • #4
        Chart shows about 86,87,88F which engine heat could do if run would be that warm if lots colder outside. Now that it's messed with and recently the engine swap it was up to the person or shop to charge it to spec now lost info. Mopars (an old term for real Chrysler products) of all sorts those years older and newer totally control what's going allow or disallow the compressor thru the "computer" which is list of items and reasons. It has enough pressure if that's all it was about to engage and give info or maybe already tried and was so full just quit till reset. Unhooking battery probably isn't going to do it it's a Mopar - total computer run engine, A/C, alternator and all other engine functions.

        Edit in the chart........

        Last edited by Tom Greenleaf; 02-20-2018, 10:00 AM. Reason: add chart
        MetroWest, Boston


        • #5
          First of all, check if you have 12V at the clutch coil. If you do, the coil is fried. Lest me know