aircon fans and pulleys

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johnnysensi

Active Member
Posts
178
Location
tonbridge,kent
Can someone help...my rave won't open ....dual air con fans on front ...what does each fan do as there's different wiring to each of em on the loom...also if I have no aircon ...Can I leave the drive belt off for now as I got rattle on one of the pulleys...cheers..p.s.it's a 2.5 diesel
 
johnnysensi said:
Can someone help...my rave won't open ....dual air con fans on front ...what does each fan do as there's different wiring to each of em on the loom...also if I have no aircon ...Can I leave the drive belt off for now as I got rattle on one of the pulleys...cheers..p.s.it's a 2.5 diesel
Click to expand...
The 2 fans can run in series at half speed or in parallel at full speed, both for cooling the condensor controlled by relays 13, 18 & 19..
You can leave the belt off, personally I would not leave it off for long though.
 
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I've got no air con due to a faulty condenser...was thinking I could just leave the belt off for few months until I find another one after my holidays....I've done your air con fan mod....but with a accuspark fan thermostat...going to test it out tonight on a long drive...as block test and pressure test came back as ok ,I'm two minds weather to do my head gasket now
 
johnnysensi said:
I've got no air con due to a faulty condenser...was thinking I could just leave the belt off for few months until I find another one after my holidays....I've done your air con fan mod....but with a accuspark fan thermostat...going to test it out tonight on a long drive...as block test and pressure test came back as ok ,I'm two minds weather to do my head gasket now
Click to expand...
Is that a fixed value thermostat? If so, good luck:eek:
 
Arnt all thermostat switches fixed value???ie they switch on at a certain temp,I can set temp as it as a dial for temperatures...was going to go for drive for 30mins hard ...sit at idle,then back of the switch from idle...so anything above normal running temp and it will come on ....
 
Tell a lie it wasn't your mod I used as I didn't use any of the loom ...I just used the thermo-come-switch and run live and earth and fitted the temp probe in top hose but connected it to one ac fan...sorry bro...
 
johnnysensi said:
Arnt all thermostat switches fixed value???ie they switch on at a certain temp,I can set temp as it as a dial for temperatures...was going to go for drive for 30mins hard ...sit at idle,then back of the switch from idle...so anything above normal running temp and it will come on ....
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OK that's fine as you can adjust it. Fixed ones tend to have a wide tolerance that may not suit the car.
Just back the stat so the fans are just off when the gauge is at normal so the come on as the temperature rises slightly above normal. Most of the time they will not run then if all is well with the engine and cooling system. They will not last long if they run continuously.
 
johnnysensi said:
Tell a lie it wasn't your mod I used as I didn't use any of the loom ...I just used the thermo-come-switch and run live and earth and fitted the temp probe in top hose but connected it to one ac fan...sorry bro...
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You need both fans to run, and you need them to stop with the ignition off or you will end up with a flat battery. Should also be fused. Unless your stat can handle repeated switching of about 50 amps it's not going to end well.
Oh and if you have not got your wiring right, there could be sparks when the aircon calls the fans.
My mod uses the standard wiring and relays.
 
Bugger I only wired up one fan ...the switch doesn't need a fuse apperntly as it can handle the loads...saying that ...as I sit here waiting for dinner,think I'll add one just in case....
 
Brother thank you for all help...it is much appreciated ...let's hope it sorts it as I want to go France in July for a camping trip....and a bit of a chalet hunt as well ,while I'm there
 
johnnysensi said:
Bugger I only wired up one fan ...the switch doesn't need a fuse apperntly as it can handle the loads...saying that ...as I sit here waiting for dinner,think I'll add one just in case....
Click to expand...
No fuse and it will burn when something goes wrong. Don't forget you need the fans to go off when the ignition is off, the battery will go flat very quickly otherwise, especially is the stat contacts weld through overload.
 
Well the aircon fans worked a treat...11-12 o'clock temp gauge on a good long run...in traffic it didn't overheat....thermostat is set to around 91-93°at Mo...thinking of kicking up a right stink at island4x4...as this was the second viscous unit...I exchanged the first one as I thought it wasn't doing the job,turns out the second one is also pants as well...after some digging and helpful advice from bmw ,I now know the fans supplied with the bi metallic coil front ,Arnt the correct viscous fans for a m51 bmw engine...tomorrow I'm off for a 200miles jaunt around the coast....with a spare bmw viscous fan in the boot lol....No coolant loss either for a change,I had a thought it was boiling over rather than a leak...thanks again ..
 
johnnysensi said:
Well the aircon fans worked a treat...11-12 o'clock temp gauge on a good long run...in traffic it didn't overheat....thermostat is set to around 91-93°at Mo...thinking of kicking up a right stink at island4x4...as this was the second viscous unit...I exchanged the first one as I thought it wasn't doing the job,turns out the second one is also pants as well...after some digging and helpful advice from bmw ,I now know the fans supplied with the bi metallic coil front ,Arnt the correct viscous fans for a m51 bmw engine...tomorrow I'm off for a 200miles jaunt around the coast....with a spare bmw viscous fan in the boot lol....No coolant loss either for a change,I had a thought it was boiling over rather than a leak...thanks again ..
Click to expand...
The correct viscous does have a coiled bi-metallic strip at the front for the M51 as fitted to the P38, I have a couple of originals.
If you are going to rely on the electric fans, you need to remove the plastic cowl to aid airflow.
Stat should be set as follows:- engine fully up to temperature, turn the dial slowly so the fans just start, back off slowly until they stop.
the temperatures marked on stat dials are not accurate, 91-93 may mean the fans are on when they are not required which will knacker the fans.
 
Bi metallic coil is a old fan apperntly and was updated to single metal plate version maybe just bmw changed its design and land rover didn't feel the need too...I have a orignal viscous fan also which has a metal plate and no coil....strange one with these viscous fans....I have both fans with the same part number...lol
 
johnnysensi said:
Bi metallic coil is a old fan apperntly and was updated to single metal plate version maybe just bmw changed its design and land rover didn't feel the need too...I have a orignal viscous fan also which has a metal plate and no coil....strange one with these viscous fans....I have both fans with the same part number...lol
Click to expand...
Never seen one on the P38 without the coil.
 
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