moved from Discussion to Tech Matters
I have a 1-yr old Freelander TD4 with an air con problem which seems to mystify the dealership. It was barely 7 days old when the air con system completely discharged. The dealer reseated a pipe but the system has never worked entirely satisfactorily since. Recently, after driving for about 2 hrs, the air flow through the vents starts to slow down causing the temperature in the car to increase. After a further 15 minutes or so the air flow virtually comes to a halt. During all this the fan sounds as though it is working normally (speed 2 or 3).
I find that if I switch the air con off, after about 10 minutes the air flow starts to increase again and 5 minutes after that it is flowing normally. However, about 2 hours later the whole cycle starts all over again.
The dealership insist that they have run the engine for up to 4 hours and cannot reproduce the fault.
Have I missed something bleeding obvious, or is the dealership backsliding ??
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Joseph,
heat exchanger icing up and blocking airflow. This melts when a/c is switched off and air flow starts again.
Just a suggestion? Might not occur in the garage/workshop if the humidity iin there is lower than it has been outside recently.
Ian L.
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Good post from Ian L. Try setting your a/c temp a bit lower and see if that helps.
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Of course I meant temp higher which means the setting should be lower Sorry.
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Yes, I agree. I has the same symptoms with my Neon in florida this year - decreasing air flow and the air vents themselves very cold to the touch.
Let it defrost for 10 mins and all ok again. We just had to learn not to turn the temperature up to it\'s coldest setting - it was ok up to about 75% \'coldness\'
It a bit rubbish though really - why have a coldest setting if the machine can\'t actually take it? - may be it\'s meant to be just a \'boost\' setting.
CF
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If your vehicle is parked for any time in high temperatures of course it will get very oppressive inside when you re-enter it. So what you do is turn up the fan to Full, roll down a window or two and run the engine for 3-4 mins or drive if you prefer for about half a mile to drive out the over-heated air. Roll the windows back up then switch on your a/c to Max until the temp inside is comfortable.
Then back off the setting to say, as Canon Fodder suggests about 75%. You should have no trouble after that assuming the a/c is in good order. If you need to run at Max cold all the time because you can\'t get a decent comfort level then either your a/c is low on freon or some other problem or it is simply under-specc\'ed for the temperatures it\'s dealing with. I have driven UK rentals with a/c\'s which are pathetically inefficient on a really hot day for this reason. Volvos and Seats seem to be the worst.
It\'s the external humidity which causes the icing because the unduly heavy outside moisture in the hot air condenses on the much relatively colder coil and freezes. Thus the cooling stops because the coil can\'t do it\'s thing till the ice melts, either when you stop the car or turn up the interior temp setting.
However problems may relate to the fact that a/c\'s are specced differently for different markets. Which is one reason why UK a/c\'s are so feak and weeble when you get a serious bit of hot weather. I suspect this the reality. You can run a Toyota a/c at full blast all day in a Kuwait August of 50 C and 90% humidity and never have a problem.
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I answered your email Joseph, but for the benefit of others here, I\'ve included the text again.
It make no difference what you set the temp to, as the evaporator will always run at between zero and 5 degC, heat is only added afterwards.
Here\'s the text:-
A very simple one. It\'s the de-ice thermostat.
On the evaporator (the bit behind the dash that gets cold), there\'s a thermostat that turns the compressor off when it gets to zero degC. When the evap gets back up to 4/5 deg, it turns the compressor back on again, and so on.
If this doesn\'t work, the condensation on the evap freezes solid, stopping the airflow. When you turn the a/c off, it allows it to defrost, and airflow improves. You\'ll notice a big pool of water under the car when it does this, whereas it should just have a steady drip all the time.
They might also know it as evaporator thermostat, compressor cut-off thermostat. For further proof, if you switch on the a/c on a cool day, fan speed no. 1, after a few minutes the compressor should start to switch on and off, maybe 30 secs on, 30 secs off. This certainly applies to petrol versions.
I\'ve not seen a TD4 freelander, only petrol version, so there is an outside chance all the above is rubbish if the car has a variable displacement compressor, as many cars now do. If this is the case, the compressor won\'t cycle, but has an internal valve that adjusts the displacement, and in that way keeps the evap at a constant temperature. If this is the case, then it needs a new compressor as it isn\'t doing it\'s job. This is unusual, as this type of compressor normal fails to minimum displacement, not maximum. They should be able to look at the gauges on their a/c machine to determine what\'s going on.
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Further to Dave N\'s comments, I was once asked to fix an \'ECU\' fault on a climate control system. It turned out that the evaporator temperature sensor (mentioned by Dave N) was a thermistor clipped to the evaporator fins. It had simply not been clipped on properly and had dropped off, dangling on its wires. An easy thing to check.
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