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The mkiv Supra Owners Club

Is heater fan speed supposed to rise/fall with engine speed?


mc92

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I had the blower fan on maximum to clear the mist off the windscreen this morning and I noticed it is lower at idle and reaches full speed at about 2000 engine rpm. I only just noticed today because my radio is broken so I can hear the fan lol.

Is this normal or is something breaking?

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13 minutes ago, mc92 said:

I had the blower fan on maximum to clear the mist off the windscreen this morning and I noticed it is lower at idle and reaches full speed at about 2000 engine rpm. I only just noticed today because my radio is broken so I can hear the fan lol.

Is this normal or is something breaking?

This is normal and the same on every car not just Supra's 🙂 I believe it's to prevent the battery draining as it isn't really recharging at idle speeds.

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I had that when I had a dynamo car going from engine idle to higher rpm. I'd recon that your battery is underpowered for what you are running at the time which could be because you have a too low Kw/hr battery to cope in the typical Winter higher draw season or your alternator is failing. The alternator is easy to check, you should be pumping out 13.6V across the battery terminals at tick over. Anything less then your alternator is struggling. Anything more is fine, it could be slightly over 14V and be normal.

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1 minute ago, rider said:

I had that when I had a dynamo car going from engine idle to higher rpm. I'd recon that your battery is underpowered for what you are running at the time which could be because you have a too low Kw/hr battery to cope in the typical Winter higher draw season or your alternator is failing. The alternator is easy to check, you should be pumping out 13.6V across the battery terminals at tick over. Anything less then your alternator is struggling. Anything more is fine, it could be slightly over 14V and be normal.

I have driven dozens of cars and all of them do this, don't think it is anything out of the ordinary and is designed to do that.

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19 minutes ago, Tyson said:

This is normal and the same on every car not just Supra's 🙂 I believe it's to prevent the battery draining as it isn't really recharging at idle speeds.

That's good to know. I've owned the car for 5 years and only just noticed 🙄

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