VW Passat B8 owners, climate control question.
Discussion
Hey
I noticed on my Passat B8 estate that if the climate control is set to off when I start the car, after running the car for a while, heat comes out of the vents still, even with the setting set to off.
Is this normal? I find I can stop it by turning the climate control on and off again.
Was driving on a hot day onces and wondered why my car just started blasting hot air, the engine temp was all normal at the time.
I'm wondering if it's a software bug since it's all digital or just something expected and common on this model
I noticed on my Passat B8 estate that if the climate control is set to off when I start the car, after running the car for a while, heat comes out of the vents still, even with the setting set to off.
Is this normal? I find I can stop it by turning the climate control on and off again.
Was driving on a hot day onces and wondered why my car just started blasting hot air, the engine temp was all normal at the time.
I'm wondering if it's a software bug since it's all digital or just something expected and common on this model
Yeah it is like the air con is on. Usually it's just whatever setting it was on previously to stopping the car on previous journey.
I mention heat because usually I turn the Aircon off and have windows open unless it's absolutely roasting. So when I start the car again it's not cold air after a few miles but warm air. Matching the setting as if I had turned the climate control on.
I mention heat because usually I turn the Aircon off and have windows open unless it's absolutely roasting. So when I start the car again it's not cold air after a few miles but warm air. Matching the setting as if I had turned the climate control on.
Yeah it does seem to be only when cars moving, does that make a difference, next time I notice it I'll stop and see if it continues at standstill after a few mins wait.
It seems the engine has to be warm for this to occur, but it might be I only notice it because after the engine is running for a bit the air is warmer than at the start of the journey
It seems the engine has to be warm for this to occur, but it might be I only notice it because after the engine is running for a bit the air is warmer than at the start of the journey
Well, if the fan isn't running then there should be nothing to drive air through the HVAC unit, unless of course air is being forced into it, i.e a ram air effect when the vehicle is moving.
In modern climate control HVAC units there is no water valve on the heat exchanger. Instead there is a constant flow of coolant, so once the engine is up to temperature the heat exchanger will be hot. The temperature of the air that ultimately comes out of the vents is controlled by a flap operated by a stepper motor which directs a certain amount of the incoming air over the heat exchanger. If your previous settings before shutting off the system are such that the temperature flap is allowing air to pass over the heat exchanger, then any air coming out of the vents will be warm.
Of course there shouldn't be any air from the vents when the system is off. There are a number of other flaps which control the distribution of the air to the various vents, and there is also usually a ram air flap which is used to compensate the effect of air being forced into the HVAC unit as the car is moving. Some or all of these should close when the system is turned off to prevent air from the vents. This might not be happening because a motor on the flap has failed or maybe the stop positions for the motors need resetting. It could even be something that's slipped through the net during calibration of the system, the motors not returning to the closed position when the car is keyed on with the climate off.
In modern climate control HVAC units there is no water valve on the heat exchanger. Instead there is a constant flow of coolant, so once the engine is up to temperature the heat exchanger will be hot. The temperature of the air that ultimately comes out of the vents is controlled by a flap operated by a stepper motor which directs a certain amount of the incoming air over the heat exchanger. If your previous settings before shutting off the system are such that the temperature flap is allowing air to pass over the heat exchanger, then any air coming out of the vents will be warm.
Of course there shouldn't be any air from the vents when the system is off. There are a number of other flaps which control the distribution of the air to the various vents, and there is also usually a ram air flap which is used to compensate the effect of air being forced into the HVAC unit as the car is moving. Some or all of these should close when the system is turned off to prevent air from the vents. This might not be happening because a motor on the flap has failed or maybe the stop positions for the motors need resetting. It could even be something that's slipped through the net during calibration of the system, the motors not returning to the closed position when the car is keyed on with the climate off.
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