Electric or Manual Fan???
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Instructor
Joined: Apr 2017
Posts: 205
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Electric or Manual Fan???
75 coupe with Vintage Air install.
All is fine, but I need to be educated a bit on cooling. Currently I have a manual fan (only 5 blades). The car nearly never reaches 200 degrees, I'd say it's at most 190. Seems to cool better sitting still than while driving.
Has front air dam and currently have no cooling issues.
BUT, I'm thinking about adding an electric fan. Everything I've read said if you have A/C and want to go to an electric fan only you should tie the fan to both the engine temp and to use a trinary A/C switch.
So my question is why is that required with an electric fan and NOT with a manual fan???
Is it because the manual fan is always spinning - either at speed (when it is free spinning) or while stopped?
Dumb question?
Thanks,
Len
All is fine, but I need to be educated a bit on cooling. Currently I have a manual fan (only 5 blades). The car nearly never reaches 200 degrees, I'd say it's at most 190. Seems to cool better sitting still than while driving.
Has front air dam and currently have no cooling issues.
BUT, I'm thinking about adding an electric fan. Everything I've read said if you have A/C and want to go to an electric fan only you should tie the fan to both the engine temp and to use a trinary A/C switch.
So my question is why is that required with an electric fan and NOT with a manual fan???
Is it because the manual fan is always spinning - either at speed (when it is free spinning) or while stopped?
Dumb question?
Thanks,
Len
Race Director
Joined: May 2006
Posts: 18,740
Likes: 2,583
your factory fan should have a thermostatic fan clutch which increases the speed of the fan as the temperature goes up.
On a fully cold engine you should not be able to spin the fan by hand any more than about 1 to 2 turns.
you should also confirm that your thermostat is no higher than a 180.
On a fully cold engine you should not be able to spin the fan by hand any more than about 1 to 2 turns.
you should also confirm that your thermostat is no higher than a 180.
Last edited by MelWff; Oct 18, 2017 at 11:31 AM.
Pro
Joined: Mar 2005
Posts: 635
Likes: 118
From: Lakemont, GA
I have a Street Rod with Vintage Air and electric fans. I have a relay logic setup so that the fan goes on when the set temp is reached (controlled by Holley Sniper) and when the A/C compressor is engaged.
When your A/C is running you need airflow across the condenser, a clutch fan will draw enough even when the clutch is not engaged, an electric fan needs to run (low speed is fine for A/C if you have a multiple speed fan).
I prefer electric fans, mostly because of the noise from clutch fans and improved power and efficiency.
I hope this answered your question, let me know if there is something I missed.
Thanks, Chris
When your A/C is running you need airflow across the condenser, a clutch fan will draw enough even when the clutch is not engaged, an electric fan needs to run (low speed is fine for A/C if you have a multiple speed fan).
I prefer electric fans, mostly because of the noise from clutch fans and improved power and efficiency.
I hope this answered your question, let me know if there is something I missed.
Thanks, Chris
Race Director
Joined: Apr 2007
Posts: 11,152
Likes: 890
From: South Western Ontario
The fans must be running to move air across the condenser with the AC on. If you trigger the fans with the AC clutch then the fans will always be on with the AC, even when you are driving fast enough that the fans are not needed.
The trinary switch allows you to trigger the fans by AC pressure, so the fans only come on when you are driving slow and the AC needs more airflow.
And yes, the reason you don't need it with a mechanical fan is because the fan is always moving some air.
The trinary switch allows you to trigger the fans by AC pressure, so the fans only come on when you are driving slow and the AC needs more airflow.
And yes, the reason you don't need it with a mechanical fan is because the fan is always moving some air.
