Testing non working air con



  • I knew when I bought my MX3 that it had a air con leak. I would like to get it re-gassed with UV dye to see where the leak is coming from but before that I need to know if the rest of the system is working such as the compressor.

    When I turn fans on and press A/C, nothing clicks and revs dont drop/rise to indicate that the comressor clutch is running. I suspect that something might not be quite right but would like any tips on where to start. I've heard you can turn the clutch on the compressor by hand to check for siezure but I cant seem to find it (may be lower down in engine bay?)

    It would be nice to have working air con but there is a limit on how much I'm prepared to spend.

    Regards, Tim.



  • Id be interested too, I have the same thing, press the button, light comes on, but only when the fan speed is set to the 1st position, if I put it on 2,3 or 4 the light goes out, dont know if thats normal? I also have no cooling so guessing mine needs regas and probably broke too



  • Sorry should have added, the light does come on and stays on at all fan speeds. Just seems like the typical "click" you get when activating A/C doesnt happen.



  • On mine, the 2nd fan kicks in and the revs jump up around 500-1k if that helps, but mines empty :(



  • The fan on mine doesnt operate at all on 1, with or without the air con, only 2 onwards has any flow



  • Bit of an update which I'm hoping you can help me?…...... Had the car up on the ramps today, and removed the undertray to gain access to the AC compressor. The inner wheel of the compressor turns quite freely by hand and doesnt seem siezed. However when AC is switched on with the blower fans operating, it doesnt turn.

    I'm now guessing at a electrical fault with either the compressor or a fuse. Is there a fuse I can check before letting a friend of mine (who is a mobile auto electrician btw) take a look at the wiring?



  • @201a769956=Jesta:

    The fan on mine doesnt operate at all on 1, with or without the air con, only 2 onwards has any flow

    Spooky snap.



  • was this ever fixed? still got the same with mine, clutch operates freely by hand, but nothing happens when you hit the button, cant find any fuses for the AC either



  • Get a test lamp on the wires at the compressor to see if it's getting a power feed when turned on to rule it out



  • Ok sorted this yesterday after hunting around the whole internet and finding no answers, the manual is wrong for my car atleast. Checked the manual, there is no fuse directly for the A/C, though it does use 2 fuses, the AD FAN (40amp K8[1.8]/20AMP B6[1.6]) and the 10amp for the rear wiper, yes thats right, the rear wiper, I thought wtf too, but thats what the wiring diagram states.

    You then have the A/C relays, which are in the top left of the engine bay as you look at it from the front of the car, just by the bonnet hinge. Then you have a pressure switch and a thermo switch, I have not yet found the thermo switch, but have found the pressure switch, the presure switch is shown to be located on the firewall/bulkhead, attached to a refrigerant line, on mine, there is no such pressure switch on any line, instead, its mounted on the dryer, on the rear to the right of the main radiator, the pressure switch is here. Will take a pic later when Ive actually fixed everything so I can detail this all properly on how to fix it.

    I checked the Low pressure valve first to check for refrigerant gas using a small screw driver tip, any small tip could be used though, its just a schraeder valve, the same that you see on your tyres, pushed it in (keep your face well clear and hands and arms covered incase liquid refrigerant does come out, dunno what itd do, but its probably not a good idea to get it on you, especially not your mouth and eyes. For me, nothing came out, so checked High pressure side, again, nothing, pulled off the pressure switch connector and bridged the connector, started car, turned the a/c on, could hear the clutch engage, visual check confirmed it too. So my system isnt working due to a complete lack of any refrigerant in the system.

    However, I also have another problem, my A/C light goes out on anything other than #1 Fan speed, unfortunately, #1 doesnt actually operate the fans at all, with or with the A/C on, so need to check that out, but also need to find out why the A/C is cutting out on 2,3,4 fan speeds. Will update as I figure it out, will do a full how to thread when Ive successfully figured it all out, with pics.



  • Nothing comes out my hi or low valves either but my ac still clicks on when i activate it just no cold air ofc



  • Jesta - sorry I cant be much help. I'm not intending to look at the faulty aircon this year as I've got timing belt next week and hopefully if enogh spare cash, to do the arches (catch them before the rot badly in the winter) and also refurbish the wheels.

    I will pick this up next year if nothing else major at MOT but I'm guessing at the least I will need a regas, clean and repipe at the front near the radiator as that is where it is leaking.

    Just standing in front of the aircon system at work oh wishing my MX-3 system worked like that!



  • @a47d71d8a5=DaveMc:

    Nothing comes out my hi or low valves either but my ac still clicks on when i activate it just no cold air ofc

    thatll be cos theres no coolant lol



  • @749754a0df=timorridge:

    Jesta - sorry I cant be much help. I'm not intending to look at the faulty aircon this year as I've got timing belt next week and hopefully if enogh spare cash, to do the arches (catch them before the rot badly in the winter) and also refurbish the wheels.

    I will pick this up next year if nothing else major at MOT but I'm guessing at the least I will need a regas, clean and repipe at the front near the radiator as that is where it is leaking.

    Just standing in front of the aircon system at work oh wishing my MX-3 system worked like that!

    got mine working, studied the system, ran through all the potential parts to check for working state, sourced the problem, fixed it, so far holding :)

    multimeter, screwdriver, piece of electrical wire, all you need


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