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Old 31st January 2020, 11:21   #1
mgj11
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Default Heater work for 30 minutes then goes cold

Hi wondering if anyone has had this problem and found out why. I set the heat to say 24C it get hot then after about 30 minutes blows cold air, this happens on all settings Aircon, Econ, man and auto. The aircon runs cold when needed and seems to work fine.
The engine temp is steady at just under half way.

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Old 31st January 2020, 11:50   #2
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Hi wondering if anyone has had this problem and found out why. I set the heat to say 24C it get hot then after about 30 minutes blows cold air, this happens on all settings Aircon, Econ, man and auto. The aircon runs cold when needed and seems to work fine.
The engine temp is steady at just under half way.

2.5 V6 190+
are all the vents cold or just the driver's upper ones. This is normal after the interior has reached its desired temp.

An airlock (or sludge) could cause this, has it been flushed/refilled recently? Or have you had any coolant loss?
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Old 31st January 2020, 13:56   #3
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If the needle is just under halfway then your thermostat is sticking open, run the obd temperature display, this will give you an accurate figure of what temp your engine is at.
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Old 31st January 2020, 14:47   #4
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are all the vents cold or just the driver's upper ones. This is normal after the interior has reached its desired temp.

An airlock (or sludge) could cause this, has it been flushed/refilled recently? Or have you had any coolant loss?

When the ATC (automatic temperature control or climate control) gets up to temp, I always thought it worked badly as it would put out quite cold air through the face level air vents. This air was a little too cold for my taste.

The heater bypass - below the two center vents - was set to open (to the right - blue circle) and so was letting a cold air feed (from outside) blend with the current ATC temperature. This was causing the slight draughty cold air. Setting it to the left (bypass closed - white ring) and it shuts off this cold air feed and so is warmer (if set that way in the ATC).

Also, the rear console vents will only supply outside air, chilled by the air conditioning. So, in winter close these off to stop cold draughts.
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Old 31st January 2020, 16:58   #5
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When the ATC (automatic temperature control or climate control) gets up to temp, I always thought it worked badly as it would put out quite cold air through the face level air vents. This air was a little too cold for my taste.

The heater bypass - below the two center vents - was set to open (to the right - blue circle) and so was letting a cold air feed (from outside) blend with the current ATC temperature. This was causing the slight draughty cold air. Setting it to the left (bypass closed - white ring) and it shuts off this cold air feed and so is warmer (if set that way in the ATC).

Also, the rear console vents will only supply outside air, chilled by the air conditioning. So, in winter close these off to stop cold draughts.
The top vents on the drivers side, face level, door and windscreen will be cooler than the passenger side, once the interior has reached its target temp.

I dont know what your issue is, just wishing to be clear, as I have seen others think that it is running cold, but it is a safety function of the atc to reduce drowsiness. Others were ready to pull out the matrix etc thinking the system was faulty when it was functioning correctly. It can get quite cold and draughty after a while. It was a good idea, but not implemented very considerately (in my opinion and experience).

If when this happens, and your foot well vents on both sides are blowing cold too, then you do have a problem. If they are warm, then it is this safety function operating. I dont drive long enough for it to happen much, but if I recall switching out of auto, will then allow the warmth to recommence from the drivers side.

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Old 31st January 2020, 18:45   #6
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The top vents on the drivers side, face level, door and windscreen will be cooler than the passenger side, once the interior has reached its target temp.

I dont know what your issue is, just wishing to be clear, as I have seen others think that it is running cold, but it is a safety function of the atc to reduce drowsiness. Others were ready to pull out the matrix etc thinking the system was faulty when it was functioning correctly. It can get quite cold and draughty after a while. It was a good idea, but not implemented very considerately (in my opinion and experience).

If when this happens, and your foot well vents on both sides are blowing cold too, then you do have a problem. If they are warm, then it is this safety function operating. I dont drive long enough for it to happen much, but if I recall switching out of auto, will then allow the warmth to recommence from the drivers side.

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Sorry, did not add a first line. Should have read "In addition to what was said above : ".

I don't have an issue with climate, only the OP. I was just adding extra detail to hopefully explain why it acts as it does.

I totally understand what you are saying. Simply turning the bypass wheel gives me warm air rather than the blend air, which I found draughty.
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Old 31st January 2020, 19:26   #7
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Sorry, did not add a first line. Should have read "In addition to what was said above : ".



I don't have an issue with climate, only the OP. I was just adding extra detail to hopefully explain why it acts as it does.



I totally understand what you are saying. Simply turning the bypass wheel gives me warm air rather than the blend air, which I found draughty.
This is independent of the by pass wheel. Mine permanently closed anyway, but is set to be warm rather that bypassed.

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