Manual Fan or Electric Fans which is best and why?
#21
08-04-2016, 07:36 PM
Veteran Member
On my XJ40 the twin electric fans are switched with a big green relay, DBC11617.
The fan on/off cycle is governed by the rad thermal switch DBC10013 (located in the bottom of the rad) and the a/c trinary switch LMB7657AA.
This is how the fan system operates on the 40 (thanks to Bryan N on Jag-lovers)
and
HTH
Larry
The fan on/off cycle is governed by the rad thermal switch DBC10013 (located in the bottom of the rad) and the a/c trinary switch LMB7657AA.
This is how the fan system operates on the 40 (thanks to Bryan N on Jag-lovers)
Here's the way I understand (in part) that the cooling fan system works.
If you select A/C then the A/C compressor relay is energised _and_ the 'trinary switch' in the A/C high pressure line is made so that both the compressor and the right (upper) cooling fan work _providing_ that there is adequate pressure in the A/C system (between 29 and 392 psi).
Similarly, with or without the A/C selected, if the A/C system pressure exceeds 392 psi, the relays (in the green relay module) governing the right (upper) and left (lower) cooling fans will energise to drive both fans.
Further, with the A/C selected (and the ignition 'ON'), if the A/C system pressure exceeds 218 psi as measured by the single pressure switch in the A/C system, a dedicated relay in the green fan control relay module will energise to drive the left (lower) cooling fan in isolation.
Even if the A/C is _not_ selected and the coolant temperature (as measured by the radiator thermal switch) exceeds 186º F, a dedicated relay in the green fan control
module will be energised to drive the left (lower) coolant fan, but that will switch off if the coolant temperature drops below 173º F.
However, if the coolant temperature exceeds 212º F, the relays in the green fan control relay module will all energise to switch on both the left (lower) and right (upper) fans.
If you select A/C then the A/C compressor relay is energised _and_ the 'trinary switch' in the A/C high pressure line is made so that both the compressor and the right (upper) cooling fan work _providing_ that there is adequate pressure in the A/C system (between 29 and 392 psi).
Similarly, with or without the A/C selected, if the A/C system pressure exceeds 392 psi, the relays (in the green relay module) governing the right (upper) and left (lower) cooling fans will energise to drive both fans.
Further, with the A/C selected (and the ignition 'ON'), if the A/C system pressure exceeds 218 psi as measured by the single pressure switch in the A/C system, a dedicated relay in the green fan control relay module will energise to drive the left (lower) cooling fan in isolation.
Even if the A/C is _not_ selected and the coolant temperature (as measured by the radiator thermal switch) exceeds 186º F, a dedicated relay in the green fan control
module will be energised to drive the left (lower) coolant fan, but that will switch off if the coolant temperature drops below 173º F.
However, if the coolant temperature exceeds 212º F, the relays in the green fan control relay module will all energise to switch on both the left (lower) and right (upper) fans.
The 'trinary switch', as it's name suggests, has three functions.
1) It energises the compressor clutch relay when the A/C pressure is between 29 and 392 psi if A/C is selected.
2) It de-energises the compressor clutch relay if the A/C pressure falls below 29 psi to [prevent damage to the compressor
3) It energises both relay elements in the fan control relay module if the A/C pressure exceeds 392 psi to drive BOTH the fans
So, it is NOT true to say that the upper right fan will run whenever A/C is selected.
I should have said that, providing that the coolant temperature does not exceed 212º F with A/C selected the upper right fan will only work if the A/C system pressure exceeds 392 psi.
1) It energises the compressor clutch relay when the A/C pressure is between 29 and 392 psi if A/C is selected.
2) It de-energises the compressor clutch relay if the A/C pressure falls below 29 psi to [prevent damage to the compressor
3) It energises both relay elements in the fan control relay module if the A/C pressure exceeds 392 psi to drive BOTH the fans
So, it is NOT true to say that the upper right fan will run whenever A/C is selected.
I should have said that, providing that the coolant temperature does not exceed 212º F with A/C selected the upper right fan will only work if the A/C system pressure exceeds 392 psi.
Larry
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#22
08-05-2016, 01:16 AM
#23
08-05-2016, 01:24 AM
Hi Jagboi
If the blades were any longer than the White/Yellow Fans, I cannot see how the Blades would fit in the Shroud.
Also I noticed that the Black Fans seem to be made of different plastic, which seemed to be less flexible and have to say that was one of the things that really put me off buying one.
If the blades were any longer than the White/Yellow Fans, I cannot see how the Blades would fit in the Shroud.
Also I noticed that the Black Fans seem to be made of different plastic, which seemed to be less flexible and have to say that was one of the things that really put me off buying one.
#24
08-05-2016, 03:31 AM
Veteran Member
The reason the new fans are black is simple: UV light.
White plastic will turn brittle under UV light. Black plastic doesn't. That is why black cable ties are the norm from manufacturers.
And before someone says UV rays don't get in that area... They do... Even if it is only opening the bonnet. Reflection from wet roads is a culprit too.
Just to explain why the fans are now days black and not a hygienic white...
White plastic will turn brittle under UV light. Black plastic doesn't. That is why black cable ties are the norm from manufacturers.
And before someone says UV rays don't get in that area... They do... Even if it is only opening the bonnet. Reflection from wet roads is a culprit too.
Just to explain why the fans are now days black and not a hygienic white...
Last edited by Daim; 08-05-2016 at 03:57 AM.
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#25
08-05-2016, 08:56 AM
The reason the new fans are black is simple: UV light.
White plastic will turn brittle under UV light. Black plastic doesn't. That is why black cable ties are the norm from manufacturers.
And before someone says UV rays don't get in that area... They do... Even if it is only opening the bonnet. Reflection from wet roads is a culprit too.
Just to explain why the fans are now days black and not a hygienic white...
White plastic will turn brittle under UV light. Black plastic doesn't. That is why black cable ties are the norm from manufacturers.
And before someone says UV rays don't get in that area... They do... Even if it is only opening the bonnet. Reflection from wet roads is a culprit too.
Just to explain why the fans are now days black and not a hygienic white...
I never knew that but why are the Black Fan Hubs only half the thickness (1 inch) of the OEM Original (2 inches)
#26
08-05-2016, 09:22 AM
Veteran Member
Probably because the Material is a more robust stuff. Think this way: Your new fans are black and quite thin too compared to the white fan. And they spin at a lot higher rpm. Why should a fan spining at tops 6000 rpm (when the clutch is worn and doesn't allow any slip) have to be thicker than one spining at more than 10000 rpm?
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orangeblossom (08-05-2016)
#27
08-06-2016, 11:24 PM
Senior Member
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orangeblossom (08-07-2016)
#28
08-08-2016, 03:20 PM
Senior Member
I've wanted electric fans since I bought the car and read about them in Kirby Palm's book. Finally got a set from V12s (complete with the transmission cooler option) a couple of months ago and while they move quite a bit more air out from under the car, the temperature gauge reads consistently warmer than it did with the stock setup. The needle seems to wander a bit less but I thought everything would run cooler. As to the noise, the electric fans are quite a bit louder than the old mechanical fan. And higher pitched. So, the jury is still out.
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orangeblossom (08-08-2016)
#29
08-08-2016, 04:31 PM
I've wanted electric fans since I bought the car and read about them in Kirby Palm's book. Finally got a set from V12s (complete with the transmission cooler option) a couple of months ago and while they move quite a bit more air out from under the car, the temperature gauge reads consistently warmer than it did with the stock setup. The needle seems to wander a bit less but I thought everything would run cooler. As to the noise, the electric fans are quite a bit louder than the old mechanical fan. And higher pitched. So, the jury is still out.
I was kinda thinking that might be the case, so I've also got a Mechanical Fan as another option, just in case I change my mind.
#30
08-08-2016, 06:49 PM
Veteran Member
Well, I don't think a mechanical fan can do what an electric fan can do at idle. It's impossible unless you rev up the car to make it turn faster. My cars with a mechanical fan, in extreme weather (95 degrees+) will eventually get hot and the A/C won't cool after sitting 30 minutes in traffic. My car with an electric fan won't do that
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#31
08-08-2016, 07:41 PM
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i read some place M/B will offer someone to make a silent automobile fan, $1 million for patent.
many people who own M/B dont like the fan noise(biggest complaint), especially after shopping and engine is still hot, in market parking lot, everyone walking by looks at them, fans are roaring! LOL.
many people who own M/B dont like the fan noise(biggest complaint), especially after shopping and engine is still hot, in market parking lot, everyone walking by looks at them, fans are roaring! LOL.
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orangeblossom (08-09-2016)
#32
08-09-2016, 12:54 AM
Well, I don't think a mechanical fan can do what an electric fan can do at idle. It's impossible unless you rev up the car to make it turn faster. My cars with a mechanical fan, in extreme weather (95 degrees+) will eventually get hot and the A/C won't cool after sitting 30 minutes in traffic. My car with an electric fan won't do that
Not such a problem in the UK, most of the time we'd be lucky to see 20o/c. and never had a problem with my Grey XJS where the barrel on the Temp gauge hardly ever goes more than a quarter the way up.
So for and against for both systems depending upon the Climate where you live.
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Spikepaga (08-09-2016)
#33
08-09-2016, 10:38 AM
Veteran Member
Hi Spike
Not such a problem in the UK, most of the time we'd be lucky to see 20o/c. and never had a problem with my Grey XJS where the barrel on the Temp gauge hardly ever goes more than a quarter the way up.
So for and against for both systems depending upon the Climate where you live.
Not such a problem in the UK, most of the time we'd be lucky to see 20o/c. and never had a problem with my Grey XJS where the barrel on the Temp gauge hardly ever goes more than a quarter the way up.
So for and against for both systems depending upon the Climate where you live.
I do wonder why they never bothered to install electric fans on the XJS though, seeing that even the XJ40's had them...
And also another related question would be...is there any aftermarket fan that can do what a OEM fan does? I've been using SPAL fans as pushers in my cars, but Maybe nothing is designed to move like OEM fans...
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orangeblossom (08-09-2016)
#34
08-09-2016, 12:03 PM
Veteran Member
Mark
SPAL fans are used in lots of OEM applications: Ferrari, Maserati, etc etc. I do believe they are the best you can get as an individual; just a matter of getting large enough ones! However, OEM fans are undoubtedly built better than most aftermarket ones, that is for sure, and a decent marque's fans, (eg Merc, Jaguar, BMW, Volvo, USA marques) will be great bargains from breakers' yards.
Greg
SPAL fans are used in lots of OEM applications: Ferrari, Maserati, etc etc. I do believe they are the best you can get as an individual; just a matter of getting large enough ones! However, OEM fans are undoubtedly built better than most aftermarket ones, that is for sure, and a decent marque's fans, (eg Merc, Jaguar, BMW, Volvo, USA marques) will be great bargains from breakers' yards.
Greg
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orangeblossom (08-09-2016)
#35
08-09-2016, 12:35 PM
Hi Mark
I've got a pair of efans from an XJ40 V12 6.0L but Since I've also managed to get a New Mechanical Fan, I will wait till my Re-Cored Rad comes back before deciding on which way to jump.
I may Test her with the Mechanical Fan, just to get her started and back on the road and think about 'modding' her later with the efans.
I've got a pair of efans from an XJ40 V12 6.0L but Since I've also managed to get a New Mechanical Fan, I will wait till my Re-Cored Rad comes back before deciding on which way to jump.
I may Test her with the Mechanical Fan, just to get her started and back on the road and think about 'modding' her later with the efans.
#36
08-09-2016, 09:47 PM
Senior Member
With electric fans, the temp gets to the top of the N in traffic, whether or not the air conditioning is on, but rarely seems to get any higher than that, even after shutdown.
But I have not had a lot of time with the new system and, to complicate things, I like driving without air-conditioning and often forget to turn it on. Of course, my '88.5 seems to turn the air conditioning on for its own use, at its own will, so that may not be relevant.
I need to relocate my infrared thermometer or buy a new one.
Last edited by Rhett; 08-09-2016 at 09:50 PM.
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orangeblossom (08-11-2016)
#37
08-10-2016, 08:58 AM
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#38
08-10-2016, 09:21 AM
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As soon as I turned on the air conditioner in bumper-to-bumper traffic or parking lot conditions, the temperatures went to the top of the N and above the N after shutdown.
With electric fans, the temp gets to the top of the N in traffic, whether or not the air conditioning is on, but rarely seems to get any higher than that, even after shutdown.
With electric fans, the temp gets to the top of the N in traffic, whether or not the air conditioning is on, but rarely seems to get any higher than that, even after shutdown.
The coolant gauge indication after engine shutdown is a result of normal heat soakback once the coolant stops recirculating and has nothing to do with fan type or it's power source. Most cars actually achieve the highest coolant temp peak after shutdown and not while running. If there's a weakness in the system, that's when it will show up.
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#39
08-10-2016, 09:26 AM
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Rhett:
It sounds to me like the Efan installation in your car is operating just right. along with the rest of the cooling system and the thermostat.
Temp goes to optimum and stays there. AC or no AC!!!
Geez, why not eliminate the water pump and rely on super old tech,
thermo siphon alone, ala Henry's T's from 09-27!!!
Total elimination of a "fan belt" would seem to be a goal.
My lump has not only efans, but an electric water pump. I am pleased.
Now, if I'd get off my.... and fix the AC...
Carl
It sounds to me like the Efan installation in your car is operating just right. along with the rest of the cooling system and the thermostat.
Temp goes to optimum and stays there. AC or no AC!!!
Geez, why not eliminate the water pump and rely on super old tech,
thermo siphon alone, ala Henry's T's from 09-27!!!
Total elimination of a "fan belt" would seem to be a goal.
My lump has not only efans, but an electric water pump. I am pleased.
Now, if I'd get off my.... and fix the AC...
Carl
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#40
08-11-2016, 03:49 AM
I'm not quite at the point where I'm willing to go back just yet. My sense is that the stock mechanical fan/auxiliary electric fan did a better job keeping the car cool at all times, as long as the air conditioner was NOT on. As soon as I turned on the air conditioner in bumper-to-bumper traffic or parking lot conditions, the temperatures went to the top of the N and above the N after shutdown.
With electric fans, the temp gets to the top of the N in traffic, whether or not the air conditioning is on, but rarely seems to get any higher than that, even after shutdown.
But I have not had a lot of time with the new system and, to complicate things, I like driving without air-conditioning and often forget to turn it on. Of course, my '88.5 seems to turn the air conditioning on for its own use, at its own will, so that may not be relevant.
I need to relocate my infrared thermometer or buy a new one.
With electric fans, the temp gets to the top of the N in traffic, whether or not the air conditioning is on, but rarely seems to get any higher than that, even after shutdown.
But I have not had a lot of time with the new system and, to complicate things, I like driving without air-conditioning and often forget to turn it on. Of course, my '88.5 seems to turn the air conditioning on for its own use, at its own will, so that may not be relevant.
I need to relocate my infrared thermometer or buy a new one.
We don't get your kind of Temps in the UK average about 20/c but even so I've decided to fit efans, or at least try them out and see how they go.
I've also got a back up plan, with a New Mechanical Fan standing by, just in case it doesn't work out.