Electric fan conversion worthwhile?

Lv1G6He3V2 · February 24, 2012

I'm looking at an electric fan conversion package. It's on eBay, comes with dual fans, shroud, all mounting hardware, relays, wiring, fuses, indicators and some kind of auto/manual controls that fit in the glove box. The only hard part looks like a ~36 mm bolt.

People say the electric fan conversion improves gas mileage, throttle response, a/c cooling, and reduces load on the water pump. The benefits to a/c and water pump are easy to believe. But the gas mileage and throttle response seem questionable.

From what I've read an automobile's fan is normally only intended to spin at idle or under heavy load; during normal driving, air is forced through the radiator anyway so the mechanical fan is designed to shut off (technically it's something called a viscous clutch?). Also electric fans take more amps from the alternator, which increases load on the engine (more resistance -> more electricity produced, right?).

So what benefits do you get from an electric fan conversion?

If not worth it, why do the 2005 and newer trucks come with electric fans?

Chris · February 24, 2012

well the 05-up trucks got a bigger radiator as well.

TimmyG · February 24, 2012

Trucks tv show did it to a ram just to test that. They did gain mpg i dont remeber how much tho.

Jennabear · February 24, 2012

They are beneficial, but when the PCM controls them. Essentially, you want them to be on only when needed (ie. specific temps) and at different speeds.

The less amount of time that the fans are used, and the lower the speed the more efficient they are- this is where having the PCM tell them when to come on and when not to, is beneficial.

Lv1G6He3V2 · February 24, 2012

I know the electric fans will be thermally controlled (and turn on with the a/c), but they have their own sensors that plug into the radiator. Basically I would be calibrating them by watching the engine temps (at idle) on the dash gauge. Is this nearly as efficient as PCM controlled fans?

dewfpo · February 24, 2012

Are these dual speed fans?

DEWFPO

Hoe-n-it · February 24, 2012

The greatest benefit I could tell with the electric fans on my 2011 Tahoe vs. the clutch fan on my old Yukon is the A/C cools MUCH better at a stop or when in traffic. The electric fans come on and pull air through the A/C condenser coil which is needed for the A/C to cool. They come on even if the motor temp doesn't call for additional cooling.

Lv1G6He3V2 · February 26, 2012

The ad doesn't say anything about dual-speed. Good point, I will ask about it. "FFD" makes the fans.

Since you mention it, my a/c unit's performance was poor last summer. The cab air filter(s) were replaced and a/c was recharged, at the start of routine maintenance. But I still had to turn it up to 100% on hot days and even then the cab really only came down to a comfortable temperature 20+ minutes into the trip. When a/c is on, a rattling sound can be heard from the engine compartment. A mechanic told me it's the condenser. If the electric fan conversion improves the a/c, I would appreciate it.

93gmc$$ · February 26, 2012

I tried this on my K1500. I bought a kit from LMC. I had to add a 50 amp relay so the fan would only run with the ign on. It definitely freed up some power, increased gas mileage a little. Temps were less steady than with the engine driven fan. I went back to the OEM setup after blowing up my A/C--you MUST have the fans on when the A/C is on...I learned this the hard way; should have wired another switch to the compressor to turn on the fan.

CapitalTruck · February 27, 2012

If your current setup ain't broke I wouldn't fix it. They might have put bigger Alts on the 05 to compensate for the load of the fan. Might want to check on that.

nickvrebel · February 27, 2012

They are beneficial, but when the PCM controls them. Essentially, you want them to be on only when needed (ie. specific temps) and at different speeds.

The less amount of time that the fans are used, and the lower the speed the more efficient they are- this is where having the PCM tell them when to come on and when not to, is beneficial.

AGREED!!!

I did the electric fan conversion on my '03 truck. Throttle response was very noticeable and I gained ~1 mpg in efficiency.

PCM controlled fans will operate the way the factory setups do, the PCM tells them when to turn on, can turn them off when above certain speeds (not needed b/c of natural airflow) and turn them on and off with the a/c compressor, which as someone else mentioned above is a must.

Most custom tuners (NOT handhelds) will make the setting changes in the PCM for you no problem and can either supply you with a harness or direct you to where you can find one. Manual control is completely unnecessary.

Lv1G6He3V2 · February 27, 2012

Great, looks like I will do the electric fan conversion before summer temps hit the area.

Sales rep says the kit comes complete with all fuses, relays, wires, etc and will automatically turn on with a/c or when engine reaches a high temperature. He did not mention if fans will turn off at highway speeds but I expect the included radiator temperature sensors will cool down anyway when there's enough airflow.

I'm getting 21 mpg (driving efficiently) on mixed backroads/highway, assuming that GT tuner is calibrated correctly...

Jennabear · February 27, 2012

I would not recommend radiator probes. That is not an efficient way to detect temps, and forces you to drill unnecessary holes.

Lv1G6He3V2 · February 28, 2012

I see Nelson and Black Bear sell harnesses that will connect electric fans to the PCM. Is a tune required to make these harnesses work with my older PCM? Your FAQ does not mention electric fans. I had hoped to avoid the time/expense of picking parts myself and getting a tune.

Pdfire119 · April 30, 2013

Is it possiable to remove the single style fan in a 04 tahoe, and replace with a duel oem fan from a 06 tahoe? Would it just be a plug and play since everything is factory or would there be more to it?