Electric fans

[dieselman123]

I have a 83 c10 with dual electric fans and want to know how to go about turning the fans off at higher speeds with A/C on. is there a way to wire this up

[VileZambonie]

Why would you turn it off with the AC on? You need the fan to keep the high side pressure in range. You could install a pressure switch on the high side but it would hardly be worth it.

[dieselman123]

I feel as though there is no need to have the fans on while driving 50+ mph.....

[Rapid Roy]

Fans are necessary for system cooling.

You can connect a cut off switch on each one. Go for a drive.

Please report back with the results.

[VileZambonie]

Modern systems use a high side pressure transducer where the PCM closely monitors high side pressure. If it determines system pressure is in optimal range for conditions it can energize and de-energize the fan relay as needed. Unless you can closely monitor this you run too high a risk of damaging the system. Relying on ram air isn't good enough as high side pressure can climb too rapidly.

[bd]

Why would you turn it off with the AC on? You need the fan to keep the high side pressure in range. You could install a pressure switch on the high side but it would hardly be worth it.

Modern systems use a high side pressure transducer where the PCM closely monitors high side pressure. If it determines system pressure is in optimal range for conditions it can energize and de-energize the fan relay as needed. Unless you can closely monitor this you run too high a risk of damaging the system. Relying on ram air isn't good enough as high side pressure can climb too rapidly.

Agreed.  A/C performance can suffer dramatically to the extent of blowing the pressure relief valve and releasing refrigerant into the atmosphere, to tossing belts, to damaging seals, switches and/or the compressor.

[JohnnyPopper]

I just installed a electric fan, with a thermo adjuster that has a temp probe.

I also have AC so thanks for the tip, I will adjust it to the lowest setting so it runs most of the time.

ALL I KNOW IS that I feel like I picked up15+ horsepower!

Does anyone know how much it takes to drive a five blade fan and clutch?

Must be a lot, because she acts like she just woke up and wants to run!

[bd]

Rather than have the fans turn on at low engine temperature, install a relay to override the temp control when the A/C compressor clutch engages.

[JohnnyPopper]

THAT is an excellent idea!

Thanks BD!

[roundhouse]

Most modern cars run the fans when the AC compressor is on

Be pretty easy to use a relay that uses water temp and is over ridden by the AC compressor signal

https://youtu.be/-954_wpRWsQ

[Mario]

Run one fan on with a relay based on temperature or A/C ON.  Run the 2nd fan on a manually switched relay.  You could have the 1st fan on a manually off circuit with the ground wire.  I know first hand that ram air from speeds above 25 mph is enough cooling especially with a large aluminum radiator.  As long as you're not in Arizona in mid-summer.   

[75gmck25]

A/C performance is much better with consistent air flow, so I would set up one fan to run whenever the A/C is on, and then use a temp controller to turn on both fans when needed for cooling.  This is a very typical setup for modern cars.  There are aftermarket electronic controllers that do this, but they are usually quite expensive. 

My understanding is that both Volvo and Ford used similar high-amperage controllers that you could pull from the junkyard.  I think it was Ford Windstar that used the dual fan controller and there are quite a few conversion articles online.

Bruce