Radiator fan on all the time when AC is on

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Verdel, Aug 13, 2018.

  1. Verdel

    Verdel Medium Load Member

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    Freightliner Columbia 2007. Just replaced the AC compressor and the dryer, put new switches on the dryer, pulled a deep vacuum - no leaks anymore. Recharged the system and now the radiator fan is on all the time, when using the AC, even at highway speeds.

    The gauges are showing 250-300 high side and 35-40 low side. Did I overcharge the system?

    Also I did not pay attention how the dryer was connected, so I did connect the "IN" marked hole to the bottom line - coming out of the radiator mounted condenser. Is this correct?
     
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  3. Hulld

    Hulld Road Train Member

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    Your readings are high on both sides.
    Did you put in the exact amount of Freon that the sticker on the firewall dictated?
     
  4. Verdel

    Verdel Medium Load Member

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    No, I just watch the AC gauges and the compressor turning on and off. The old compressor was fine even with this readings, but probably was low on oil. With the new one (full with oil), can`t fit that much of Freon anymore and the system was overcharged. Extracted some Freon back to my canister and now everything is back to normal.....
     
  5. Rideandrepair

    Rideandrepair Road Train Member

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  6. Verdel

    Verdel Medium Load Member

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    Yes, I overcharged the system. This was the problem.
     
  7. Cattleman84

    Cattleman84 Road Train Member

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    Over charged AC system will cause that every time.
     
  8. Rideandrepair

    Rideandrepair Road Train Member

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    Done that before it acts just like it’s low especially if hi pressure switch is bad. I blew my compressor split wide open last year overfilling it.Thought it was a little low!!! I put that green dye in it this time.Also learned better to be a little low on oil than too much as the oil displaces Freon and caused compressor to run hot.Always Thought a little extra oil was a good thing made sense to me.Ive been doing my own since 1998 when I got ripped off at the T A. Even keep a vacuum pump under the bunk.Just when you think you got it all figured out learn something new about A/C. I used to just fill it till compressor first shuts off and then watch it for a while and make sure it was cycling on for a good while longer than not. Not exact science but It worked.Now I got the gauges.Basically flush lines replace condenser if lines were really dirty. Replace compressor air drier and at hi pressure switch pull vacuum fill with correct amount from tag on firewall.And if you’re lucky you’ll get at least 2 or 3 yrs out of it!!!
     
  9. Rideandrepair

    Rideandrepair Road Train Member

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    Glad you got it fixed!!! The clue was fan on all time pressure too high!!! I shoulda caught that one
     
    Tug Toy Thanks this.
  10. Hulld

    Hulld Road Train Member

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    That’s what I was getting at when I said both pressures are to high and did you put the exact amount of Freon in from the tag on the fire wall.
     
  11. Rideandrepair

    Rideandrepair Road Train Member

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    Lol I missed that too!!!
     
    Hulld Thanks this.
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