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Prestige Air

Discussion in 'T3 & T4 Tech Help Clinic' started by njg02, Nov 2, 2021.

  1. njg02

    njg02 Active Member

    Messages:
    128
    Location:
    Rockhampton CQ
    Got the air con regassed and nice and cool.
    But, it's connected to the high speed fan for the radiator. Wound down to low temp and the rad fan roars constantly. At about 1/4 heat the fan cycles.
    I've been told that that is how they are wired. So that the air con is efficient.
    Any ideas on a wiring change?
    Or a quieter fan?
     
  2. Barry

    Barry Well-Known Member

    Messages:
    6,158
    Location:
    Abbotsford NSW
    The condenser coil mounts in front of the radiator.
    The fan needs to blow through both coils to cool properly.
    Can’t just rely on wind power.
    Not a lot of space to put a bigger / quieter fan.

    All WBX T3’s I have had, the fan is quite noisy. I don’t have air so it doesn’t come on that much. But you know it when it does.


    Only other option is to relocate condenser coil.
    Then fan would not need to de so large.
    Have seen them mounted under car.
    Not a good idea if you go bush.
     
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  3. Grantus

    Grantus Well-Known Member

    Messages:
    18,824
    Location:
    Southern ACT
    You just need a louder sound system, so the music is what you hear, not the fan……;)
     
    Barry likes this.
  4. njg02

    njg02 Active Member

    Messages:
    128
    Location:
    Rockhampton CQ
    Thanks Barry.
    I'm lead to believe that it's a two speed fan. Could I wire it up to the low speed?

    Does anyone have a wiring diagramme?
     
  5. Barry

    Barry Well-Known Member

    Messages:
    6,158
    Location:
    Abbotsford NSW
    If you don’t cool the gas properly it won’t condense.
    This can/will lead to problems with the refrigeration cycle.

    Not like a radiator where the motor just runs a bit hot.
     
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  6. Barry

    Barry Well-Known Member

    Messages:
    6,158
    Location:
    Abbotsford NSW
  7. syncro

    syncro Well-Known Member

    Messages:
    10,365
    Location:
    Southern Highlands
    These are very big fans on Australian syncros. I think the low speed would be plenty. Have a look at other cars of that vintage that have extra fans fitted. What do you think Barry?

    You could also use an aftermarket fan if it fits.
     
    njg02 likes this.
  8. Barry

    Barry Well-Known Member

    Messages:
    6,158
    Location:
    Abbotsford NSW
    @syncro

    when you turn a condenser off and the compressor is running it gets hot.
    In a well designed system the system will trip on high heap pressure.

    I don’t know what will happen here.

    It may just cool less or it may trip or it may break.
    Never seen an over temp / high head on an automotive system.

    It’s just not as simple as the motor where you see your temp gauge rising and you can go “hmmm……. My fan is not working. Motor is getting hot. Better switch off before I do damage.”
     
    njg02 likes this.
  9. syncro

    syncro Well-Known Member

    Messages:
    10,365
    Location:
    Southern Highlands
    @Barry

    I just think that a syncro fan on high is overkill. I'd be speaking to an auto refrigeration expert for an opinion.

    I understand the high head pressure thing. I worked on an Audi with factory air that had pressure "fuses" and sensors. I just remember it was a drama gassing it.
     
    Last edited: Nov 3, 2021
    Syncro27, njg02 and Barry like this.
  10. syncro

    syncro Well-Known Member

    Messages:
    10,365
    Location:
    Southern Highlands
    Factory ac switches to high speed fan when pressure reaches 14.5 bar (210psi). Bentley page 87.6.

    Wiring diagram from page 97.142. It appears they have a 3 stage fan.

    Note; Syncros have a different fan setup compared to 2wd. The high speed relay is J135 on the A pillar. 2wd use J101 which is on the fuse box for their smaller fan.

    If this was mine, I would connect the ac to low speed fan with a changeover relay so that when the engine reaches 95C with the ac on the fan would go to high speed. With the ac off it would just work as normal.

    The advantage of fitting an extra aftermarket ac fan like most cars is that you will not be wearing out your original fan.
     
    Last edited: Nov 3, 2021
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  11. njg02

    njg02 Active Member

    Messages:
    128
    Location:
    Rockhampton CQ
    Thanks guys. Lots of great info to try to get my head around.
     
  12. njg02

    njg02 Active Member

    Messages:
    128
    Location:
    Rockhampton CQ
    Quick test on the switch last night thanks Phil. Fan works fine low and high speed.
    Warmed the motor up and aircon put the fan on low, as the Gowesty speil says.
    Will take it for another run and see how it goes.
     
  13. Andy.

    Andy. Active Member

    Messages:
    525
    Location:
    Brisbane
    My AC turns the fan on to low, would have been surprised if yours was hooked up to high speed. I have wondered if you could shut the fan off above ~80kph to save the fan but never bothered.
    Not that I have tested, but he fan would be spinning all the time with air flow at speed turn on or off, and the current draw on the fan at speed would be low anyway, so doubt you would achieve much.
    The only thing that annoys me is the thermostat in the AC turns the compressor and fans (in the cabin) off once down to temperature. I've not looked at changing this, but I would prefer the cabin fans kept going.
    That said, I usually have the thermostat at minimum temperature anyway, which keeps it on full time.
     

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