Evolution of A/C condensor fans

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meangreen01

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So, it's 90 degrees outside and it has my mind is on A/C...

Most likely basic knowledge for our resident mechanics, but how much did having only a fan clutch driven fan effect A/C performance before electric fans became the norm?

Admittedly, I've only owned one vehicle that didn't have electric cooling fans. I would think that A/C performance in the 50's, 60's, and 70's must have been negatively effected by the limitations of flow from only having a fan clutch driven fan. Especially at stop lights and in stop-n-go traffic.

Nowadays we have e-fans that run on high during A/C usage, continually removing heat from the condenser. My Durango has both, fan clutch and e-fan, and I've noticed that when I run the A/C, which engages the e-fan, my coolant temps also seems to run slightly lower and are more consistent.

So, did having only a fan clutch driven fan cause A/C performance to suffer?
 
My truck has a clutch operated fan only and the A/C has always worked great. Temps here have been pushing 100* lately and even sitting in traffic the interior stays nice and cool. It is less space to cool, and my truck has a fairly open engine compartment which helps.
 
You're assuming all fans had clutches. Anecdotal evidence to me says before 1980 some did not. Would be easy to put more blades on a fan with optional AC.

Read that an early toyota camry, getting used to the transverse engine thing, had a hydraulic fan that ran off the PS pump!
 
Originally Posted By: eljefino
hydraulic fan that ran off the PS pump!


Seriously!? Never knew that. Interesting to know. I think by the 80's e-fans were beginning to be more prevelent in cars.
 
Originally Posted By: eljefino
You're assuming all fans had clutches. Anecdotal evidence to me says before 1980 some did not. Would be easy to put more blades on a fan with optional AC.

Read that an early toyota camry, getting used to the transverse engine thing, had a hydraulic fan that ran off the PS pump!


That makes sense since I saw the same thing on Lexus.

A truck fan clutch i recently handled had an electrically controlled engagement. Big pigtail out of it with a connector plug.
 
The Caterpillar loaders at work have hydraulic fans. It's pretty elegant and easy to control, actually. Everything else is hydraulic so what the heck.

Both my BMW and the household Audi have both mechanical and electric fans. They both run the electric fans based on refrigerant pressures, coolant temp, and speed. They seem to cool more consistently in slow and stopped traffic than cars with just electric fans. They also don't have lights that dim at stoplights like Hondas. There can be some power loss and roaring when the clutches lock up, but I like the sound.

The Ford work trucks have no problem with just a mechanical fan. Good ac performance, and they stay nice and quiet.
 
Originally Posted By: meangreen01


how much did having only a fan clutch driven fan effect A/C performance before electric fans became the norm?



A mechanical fan and a working fan clutch will move more air through the radiator and condenser at all engine speeds than electric fans could ever hope for.

Plus R12 was more efficient than todays R134a.

Todays AC systems get you cooled off in a couple of blocks. The old R12 with a fan clutch got you cooled off before you got out of the parking lot.
 
Between my 2002 Ford Taurus and my 98 F150 I prefer the AC system in the F150 when it gets up to 110 outside.

Don't know why but the F150 cools off faster. It does have a fan on a clutch whereas my Taurus just has a couple of electric fans.

BTW, I just had the AC replaced in my Taurus in November, it works well, but it just takes awhile to really cool things down.
 
Why think clutch fans are inferior?
They could really push air at low speeds.
They were phased out because of complexity and loss of eficiency when driving.
 
I have had clutches and electric fans fail. I like the fact that at idle an engine driven fan is quiet, but can pull a strong breeze in through the grill. I don't like the fact that when they are fully engaged they take a lot of horsepower above idle speed. luckily they usually start to freewheel pretty quickly once you start moving. I find the roar of a mechanical fan preferable to the scream of dual electric fans. And I do remember when people ran Flex-Fans with no clutch, I don't remember why.

I think in a lot of cases, electric fans were used due to the engine sitting the wrong way in the engine compartment. although out of my 3 RWD vehicles, only one has a mechanical fan.

I also worked on a truck not too long ago that had electrical connections running into the fan clutch - I think it was an Explorer. I remember being surprised by the electrical connection there and also that it still had plug wires.
 
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And I do remember when people ran Flex-Fans with no clutch, I don't remember why.

I have had flex fans both with clutch and without, engine ran cooler without clutch. I had a clutch lock up going 65 pulling a trailer, I thought a helicopter was landing on the roof of the truck, scared my wife so she almost peed. Didn't do me any good either, but as luck would have it with in a mile was exit and an auto parts store. I got a clutch, put it on and was on my way.
 
Originally Posted By: Chris142



A mechanical fan and a working fan clutch will move more air through the radiator and condenser at all engine speeds than electric fans could ever hope for.

I wonder about that. Just doesn't seem possible with their inability to consistently deliver a set RPM level and have multiple speeds to adjust for varying conditions. Not to mention dual fan set-ups.

Originally Posted By: Chris142

Plus R12 was more efficient than todays R134a.



I 110% agree with this.
 
A lot of those belt driven fans had blades designed to flex as engine rpm increased, to provide optimum airflow for a given speed. If you had the hydro clutch, it would also decrease the slippage as the radiator airflow got hotter, even at a stop. IIRC, the new clutches with the wire are controlled by pulse modulation from the ECM. Ford calls it the vistronic. My last two trucks (powerstroke and cummins) were equipped with those, but with both of them being diesel, I don't think a factory electric fan would've cut it. I've seen multiple e-fan failures in fleets of crown vics and impalas over the years.
 
And don't forget that clutch fans have friction pads in them that wear out, and when they do wear out too much the clutch will slip too much and it will NOT turn the fan as fast as it should.

Also, on many vehicles that have clutch fans, you can replace the standard clutch with a Heavy Duty. and it will pull more air.
 
Originally Posted By: turbodieselfreak
I've seen multiple e-fan failures in fleets of crown vics and impalas over the years.


Just curious, What fleet work did you do and when?

I dont doubt your findings but im interested in what you consider "Multiple E-Fan Failures"?

Thanks
 
Originally Posted By: 123Saab
Originally Posted By: turbodieselfreak
I've seen multiple e-fan failures in fleets of crown vics and impalas over the years.


Just curious, What fleet work did you do and when?

I dont doubt your findings but im interested in what you consider "Multiple E-Fan Failures"?

Thanks
I used to be a tech a lifetime ago. Much more recently, I was the fleet officer for a chicago south suburban p.d.. The impalas were atrocious. Even with a twin fan setup, I think every one of them went in for fan replacement at least once a year (we went to the impalas when chevy discontinued the caprice). I convinced admin to go with the cvpi. It fared much better, but I would still say that fan failure rate only dropped by half. I can't speak for the charger as we only have one, but I don't recall it having any problems. This is a fleet maintained at a size of approximately twenty cars, obviously idling ALOT with a/c at full blast. I've since passed the maintenance torch on, so I can't speak of things lately.
 
You simply cannot compare an engine driven fan with an electric.

The electric excels at slower speeds and usually delivers better AC operation in tough climates. Reliability is excellent in most applications with the fan lasting the life of the vehicle. Our Silverados have infinitely variable fan speeds and are the best AC's in the world sitting still! Plus an electric either works or not, no gradual wer out or partial failures!

ANY clutched engine driven fan is very prone to wear over time, and typically gradually declines in performance over years. Some people hardly know. But in our usage a viscous clutch seldom lasts more than 100k miles no matter what.
 
Remember a good locked up manual fan can grab 10 hp and turn it into a breeze. I've seen V8s with sticky cold clutches blow a pile of leaves away that had been gathering under the car when they first start.

Electric fans would need ~550 amps at 14 volts to draw the same air, or even more considering inefficiencies. That's more than the starter motor!
 
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