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Quite agree. Mine works really well now. I did have it regassed after I fitted the new condenser and drier a couple of years ago but I don't think it was done properly. No need for a fan.
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Engine and air con cooling fans.
- Thread starter frank rabbets
- Start date
Good to hear you are a happy bunny Frank, of note you will find that certain countries did actually have an extra electric fan in front of the condenser on the LC so that at least proves there has been a call for it. I suppose there was never a call for it in the UK however, the recent changes in climate probably are showing up any weakness in the system. We know the VC fan is not driving very hard at idle and the LC is one of the few vehicles in the UK that relies on the engine driven fan to cool the engine and the AC condenser. I am not replacing my fans for the AC, I just plan to get rid of the power robbing VC fan as it is rarely needed here except when stationary and with the spare capacity of the OE system means that is a rare event.
regards
Dave
regards
Dave
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PeterLC
Active Member
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- Country Flag
Why do you need a condenser fan and idle up for AC ? Well cooling power (inside the car) is proportional to the amount of refrigreant (R134a) that can be evaporated in any amount of time. In the PH diagram from point 3 to 2. Constant pressure means constant temperature (9°C here). Higher flow means more cooling and as the compressor is a volumetric pump, we need RPMs to get there.
Increasing the condenser air flow, lowers the condenser temperature (point 1 to 4, 65°C here) and hence shifts the red box downwards so the evap temperature decreases. That's what we are after isn't it.
Increasing the condenser air flow, lowers the condenser temperature (point 1 to 4, 65°C here) and hence shifts the red box downwards so the evap temperature decreases. That's what we are after isn't it.
Good to see an old thread revived. As mentioned waaaay back I am a great believer in electric fans for both cooling and for boosting AC capability. It was mentioned earlier that some hotter climates got an additional electric fan to assist the VC unit, so clearly there is some benefit.
I will throw this out there just for the sake of it.
I did have a MK VIII fan from a yank 4.6 V8, it was a two speed unit and worked fine, on road, off road, traffic ect and never an issue but it wore out after IIRC around 4 years? It was a S/H unit and I decided to replace it with a new one however, Siemens don't make them anymore, apparently now built in Mexico and they do not appear to be the two speed versions?
One of the reasons a forum member would not replace his VC with electric was because of the sudden 'hit' the electrical system takes when the fan kicks in, a good point in particular with the single speed units. I had always run a 150 amp alternator so never really gave it a thought but it is a valid point if your alternator is tired or already taking a hit from big stereos and lighting that would not look out of place at a football ground.
So I decided to fit a Mercedes electric fan, after seeing one cool off a 450 ML I knew they were up to the task. My choice apart from it's cooling ability was the fact that it will come on at very slow revolutions and increase if the engine temperature continues to climb. And when in full flight these fans can draw IIRC around 50 amps? So the surrounding hardware has to be good, anyone who dismisses electric cooling is because they have either never tried it, or the component choice and/or the install was not up to snuff.
There are many advantages and few disadvantages to having converted to all electric. I won't go through them all but I will point out one of the single most disadvantages is there are more things to go wrong with electric, the 'keep it simple' mantra is spot on here with the VC however, thought out correctly and installed with quality components and you can put any reliability thoughts out of your mind.
I not only purchased a custom built speed controller, I added a couple of extra's myself for example, if the cooling fan is on whilst the engine is switched off, it will continue to run for a further five minutes, after the sensor has detected that the water in the sensor tube (not the engine) has cooled, this 'after run' time is adjustable but five minutes seems about right and deals well with heat soak. Having said that it barely runs on unless the AC is on and the trinary pressure switch has called for the fan. The custom speed controller also has a sensor fail safe, if the temperature sensor fails or the connection to it fails, the fan controller defaults to maximum speed.
The ability to switch off the fan for wading in deep water is great so that is a plus, being able to override the sensor and have the fan come on earlier is fitted but not found a reason to use it.
Something else, two identical fan sizes with the same pitch blades (Merc pretty much identical to the 80 in size and pitch), but one mechanical and one electric and both spinning at the same speed should pull the same amount of air through the radiator, but this is not the case. Mechanical fans must have a clearance between the blades and shroud to allow for the movement of the engine, electric fans being 'fixed' have the shroud mounted around them very close, so all air that is drawn through the blades must pass right through with none for want of better words is 'left behind'.
Something I noted with mechanical fan systems that do not have electric backup versus systems with electrical backup and/or all electric systems is the time it takes for the AC to get really cold really quick after starting up, electric assistance or all electric is way better in this area, if you think about it, you can see why.
The crux of whether you should make the effort to go all electric, or at least add an electric 'booster' fan would be if your AC is not as cold as you want it to be. And TBH, if your AC is not cooling you in a UK climate, then you can bet there is something else wrong within the system, whether it a condenser blocked, low gas, or whatever. My 80 AC seemed fine in Spain when I imported it back in IIRC 2010 after a new condenser and dryer were fitted, the conversion to all electric was originally to get rid of the mechanical fan and guessed the electric would make the AC better, and it does. FWIW I presently have a problem with the 150 amp alternator, but as the diesel electrical loads are minimal, I put on the spare 80 amp unit I normally take when off roading, we are 'suffering' 40C at present, when using the 80 and I go in a shop for instance I leave the AC on for my little dog 'Cookie', I just use the spare key to lock the door, no drama and no flat batteries.
regards
Dave
I will throw this out there just for the sake of it.
I did have a MK VIII fan from a yank 4.6 V8, it was a two speed unit and worked fine, on road, off road, traffic ect and never an issue but it wore out after IIRC around 4 years? It was a S/H unit and I decided to replace it with a new one however, Siemens don't make them anymore, apparently now built in Mexico and they do not appear to be the two speed versions?
One of the reasons a forum member would not replace his VC with electric was because of the sudden 'hit' the electrical system takes when the fan kicks in, a good point in particular with the single speed units. I had always run a 150 amp alternator so never really gave it a thought but it is a valid point if your alternator is tired or already taking a hit from big stereos and lighting that would not look out of place at a football ground.
So I decided to fit a Mercedes electric fan, after seeing one cool off a 450 ML I knew they were up to the task. My choice apart from it's cooling ability was the fact that it will come on at very slow revolutions and increase if the engine temperature continues to climb. And when in full flight these fans can draw IIRC around 50 amps? So the surrounding hardware has to be good, anyone who dismisses electric cooling is because they have either never tried it, or the component choice and/or the install was not up to snuff.
There are many advantages and few disadvantages to having converted to all electric. I won't go through them all but I will point out one of the single most disadvantages is there are more things to go wrong with electric, the 'keep it simple' mantra is spot on here with the VC however, thought out correctly and installed with quality components and you can put any reliability thoughts out of your mind.
I not only purchased a custom built speed controller, I added a couple of extra's myself for example, if the cooling fan is on whilst the engine is switched off, it will continue to run for a further five minutes, after the sensor has detected that the water in the sensor tube (not the engine) has cooled, this 'after run' time is adjustable but five minutes seems about right and deals well with heat soak. Having said that it barely runs on unless the AC is on and the trinary pressure switch has called for the fan. The custom speed controller also has a sensor fail safe, if the temperature sensor fails or the connection to it fails, the fan controller defaults to maximum speed.
The ability to switch off the fan for wading in deep water is great so that is a plus, being able to override the sensor and have the fan come on earlier is fitted but not found a reason to use it.
Something else, two identical fan sizes with the same pitch blades (Merc pretty much identical to the 80 in size and pitch), but one mechanical and one electric and both spinning at the same speed should pull the same amount of air through the radiator, but this is not the case. Mechanical fans must have a clearance between the blades and shroud to allow for the movement of the engine, electric fans being 'fixed' have the shroud mounted around them very close, so all air that is drawn through the blades must pass right through with none for want of better words is 'left behind'.
Something I noted with mechanical fan systems that do not have electric backup versus systems with electrical backup and/or all electric systems is the time it takes for the AC to get really cold really quick after starting up, electric assistance or all electric is way better in this area, if you think about it, you can see why.
The crux of whether you should make the effort to go all electric, or at least add an electric 'booster' fan would be if your AC is not as cold as you want it to be. And TBH, if your AC is not cooling you in a UK climate, then you can bet there is something else wrong within the system, whether it a condenser blocked, low gas, or whatever. My 80 AC seemed fine in Spain when I imported it back in IIRC 2010 after a new condenser and dryer were fitted, the conversion to all electric was originally to get rid of the mechanical fan and guessed the electric would make the AC better, and it does. FWIW I presently have a problem with the 150 amp alternator, but as the diesel electrical loads are minimal, I put on the spare 80 amp unit I normally take when off roading, we are 'suffering' 40C at present, when using the 80 and I go in a shop for instance I leave the AC on for my little dog 'Cookie', I just use the spare key to lock the door, no drama and no flat batteries.
regards
Dave
Last edited:
