Interior blower - how powerful are yours?
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From: Surrey, UK
Interior blower - how powerful are yours?
Now my air con is recharged I'm paying a bit more attention to my interior blowers - and they are not very good.
When I turn the speed up, speed 1 doesn't seem to make any difference at all. Speed 2 is barely noticeable. Speed 3 is a bit better - and speed 4 is slightly better again, but even so - if I have speed 4 on most of the time it still doesn't seem very powerful. If I place my hand in front of the vent then I can't really feel a breeze more than about 8 inches away.
Sometimes, it seems to increase in speed - and I can actually feel a breeze where I'm sitting. But it doesn't happen most of the time.
I know from Adrians book that the speed control varies the voltage between 2 and 13v. And that the final stage amplifier can vary that. So I could check the voltage - but where? I found the connectors to the fans (red and red/brown) but the wiring diagram shows one going to the CCU and one to the amplifier - and so I don't know which is earth and which is live.
So - how powerful are peoples interior fans? And can anyone tell me how to check the voltage to mine?
When I turn the speed up, speed 1 doesn't seem to make any difference at all. Speed 2 is barely noticeable. Speed 3 is a bit better - and speed 4 is slightly better again, but even so - if I have speed 4 on most of the time it still doesn't seem very powerful. If I place my hand in front of the vent then I can't really feel a breeze more than about 8 inches away.
Sometimes, it seems to increase in speed - and I can actually feel a breeze where I'm sitting. But it doesn't happen most of the time.
I know from Adrians book that the speed control varies the voltage between 2 and 13v. And that the final stage amplifier can vary that. So I could check the voltage - but where? I found the connectors to the fans (red and red/brown) but the wiring diagram shows one going to the CCU and one to the amplifier - and so I don't know which is earth and which is live.
So - how powerful are peoples interior fans? And can anyone tell me how to check the voltage to mine?
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From: Surrey, UK
Mine do feel different - but just not very powerful although it's a subjective thing. I'd say speeds 1 and 2 are a bit pointless - they really are that weak.
I just found Randall's answer to a question I asked a few weeks ago (not only do my interior fans seem weak, I'm not sure the left one works very often) - and that did tell me which wire is live. So, tomorrow I'm going to try feeding 12v to the fans directly - and see how powerful they are. I can presumably also measure the voltage at the power to the fan when I vary the speed and make sure that it's not a lot lower than I would expect.
I just found Randall's answer to a question I asked a few weeks ago (not only do my interior fans seem weak, I'm not sure the left one works very often) - and that did tell me which wire is live. So, tomorrow I'm going to try feeding 12v to the fans directly - and see how powerful they are. I can presumably also measure the voltage at the power to the fan when I vary the speed and make sure that it's not a lot lower than I would expect.
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I'd say at speed 1 you can just about tell the air in the cabin is being moved, speed 2 feels like a gentle breeze, at 3 you can feel the air being blown at your face and 4 blows enough into your eyes that you wouldn't keep it there for long. Not powerful, but good enough. My vents are pointed at my face because my air-con is completely up the spout; no gas left to engage the compressor clutch a few weeks after a full charge. Speeds 3 and 4 make way more noise than would be expected for the amount of air they actually move, the main reason for keeping to 2 whenever possible.
I can feel a breeze at 1 with my hand 8 inches from the centre vent, and it does increase pretty much in equal steps through to speed 4. May be about the only area of my HVAC system functioning normally....
I can feel a breeze at 1 with my hand 8 inches from the centre vent, and it does increase pretty much in equal steps through to speed 4. May be about the only area of my HVAC system functioning normally....
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Some more info.
Generally, I get enough airflow through the vents with nothing dialled into the fan switch (normal UK-weather). On a warm day, I will generally set the fan to '1' and turn the air-con on and off for a few minutes at a time. When it's HOT - that's hot for us over here, of course, I hardly ever have to set 'recirculate' or go above '2' on the fan switch.
Generally, I get enough airflow through the vents with nothing dialled into the fan switch (normal UK-weather). On a warm day, I will generally set the fan to '1' and turn the air-con on and off for a few minutes at a time. When it's HOT - that's hot for us over here, of course, I hardly ever have to set 'recirculate' or go above '2' on the fan switch.
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Thread Starter
Race Car
Joined: Nov 2001
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From: Surrey, UK
OK - I just had a play with my CCU controls and here's what I found :
If I select red dot temperature, then the fans are plenty powerful. If I turn the temp right down (to blue dot or low temp) then the speed from the vents decreases massively. As it happens, it sounds like the fan doesn't slow down - but the air from the vents is much less powerful. It almost sounds like the air is being routed from somewhere else - but it's not coming out the vents or out of the windscreen demister.
If I turn the temp just off the red dot - sometimes it slows down, sometimes it will wait until I get a slightly lower temp.
Any ideas? (Other than "you've got a knackered CCU"). And - where can the air be going when this happens? It sounds like the fan speed is the same - just not much of it is directed to the vents!
If I select red dot temperature, then the fans are plenty powerful. If I turn the temp right down (to blue dot or low temp) then the speed from the vents decreases massively. As it happens, it sounds like the fan doesn't slow down - but the air from the vents is much less powerful. It almost sounds like the air is being routed from somewhere else - but it's not coming out the vents or out of the windscreen demister.
If I turn the temp just off the red dot - sometimes it slows down, sometimes it will wait until I get a slightly lower temp.
Any ideas? (Other than "you've got a knackered CCU"). And - where can the air be going when this happens? It sounds like the fan speed is the same - just not much of it is directed to the vents!
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From: Surrey, UK
Right, I've got to the bottom of this :
Red dot temp is more powerful because rear blower cranks up to high speed - so that's normal.
When I checked the fans - I get power OK to both connectors - but it turns out the RHS isn't running. If I reach around the back of the fan and jiggle the connector, I can sometimes get it running at very low speed.
A couple of years ago I had washer fluid leak - the bar between the wipers had cut through a pipe, and I think it had been like that for a while. Water would have been leaking from above this point - so I reckon the contacts to the fan are completely corroded.
It doesn't feel like it's a connector to the fan - so I can't pull it off (unless someone knows different?). I think the whole assembly will have to come out - but that looks pretty difficult.
Red dot temp is more powerful because rear blower cranks up to high speed - so that's normal.
When I checked the fans - I get power OK to both connectors - but it turns out the RHS isn't running. If I reach around the back of the fan and jiggle the connector, I can sometimes get it running at very low speed.
A couple of years ago I had washer fluid leak - the bar between the wipers had cut through a pipe, and I think it had been like that for a while. Water would have been leaking from above this point - so I reckon the contacts to the fan are completely corroded.
It doesn't feel like it's a connector to the fan - so I can't pull it off (unless someone knows different?). I think the whole assembly will have to come out - but that looks pretty difficult.
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From: Atlanta
Dave:
Have you checked the heat and vent servos? It sounds like you are on track with the fan problem, but you will get weak air flow in the dash vents if the flaps are directing some of your availabale air to the defrost and foot vents.
Closing the fresh air (recirculation) flap improves the air flow and lowers the temperature on my system when it is extremely hot and humid.
Have you checked the heat and vent servos? It sounds like you are on track with the fan problem, but you will get weak air flow in the dash vents if the flaps are directing some of your availabale air to the defrost and foot vents.
Closing the fresh air (recirculation) flap improves the air flow and lowers the temperature on my system when it is extremely hot and humid.
Last edited by springer3; Jul 24, 2004 at 05:43 AM. Reason: typo
Thread Starter
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From: Surrey, UK
Vent servos seem OK.
I decided to try getting to the fan connector by going in through the front. Took the firewall out, and took the top off the fan - but couldn't get the fan itself out (manual says you need a special tool and I could't figure out what I needed to make one).
But before I put it all back together I powered the fan - and it worked fine. Everything is back together now and the fan blows much better.
I can only think I disturbed something when I took it all apart - so I guess it won't last.
One question - how does the fan speed work? Adrians book says variable power (2 - 13v) from the speed switch. But the power at the fan is 12v all the time - in fact, it drops from about 12.5V at zero speed to 12v at speed 4 (I confirmed this is the same for the fan that works as well). So how are the fan speeds controlled?
I decided to try getting to the fan connector by going in through the front. Took the firewall out, and took the top off the fan - but couldn't get the fan itself out (manual says you need a special tool and I could't figure out what I needed to make one).
But before I put it all back together I powered the fan - and it worked fine. Everything is back together now and the fan blows much better.
I can only think I disturbed something when I took it all apart - so I guess it won't last.
One question - how does the fan speed work? Adrians book says variable power (2 - 13v) from the speed switch. But the power at the fan is 12v all the time - in fact, it drops from about 12.5V at zero speed to 12v at speed 4 (I confirmed this is the same for the fan that works as well). So how are the fan speeds controlled?
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Dave:
I don't really know, but if the supply lead is always 12 volts, it must be the earth return lead that is regulated. Check the voltage on across the fan, and I'll bet you will see the voltage change with fan speed is in the range stated in Adrian's book.
I don't really know, but if the supply lead is always 12 volts, it must be the earth return lead that is regulated. Check the voltage on across the fan, and I'll bet you will see the voltage change with fan speed is in the range stated in Adrian's book.
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I was checking across the fan - the red live lead and the red/grey and red/brown earth leads. It seemed to change speed without changing voltage (or actually, it got a faster with a small drop in voltage) which confused me!