01sleeperZ

Has anyone put an electric fan and aftermarket controler on a 6 cyl Trailblazer? I think I have a fan clutch going out, and a good electric setup would likely get better milage and less noise. But I don't want a very difficult install or durability issues. Any thoughts?

Thanks

nauticstar87

I'm unsure on the trailblazers, but I know a lot of people take electric fans from a Ford Taurus and put 'em in the 01-06 Chevy trucks. You have to have the computer tuned for it, or run the fans through a manual switch.

MDTAHOE

The trailblazer uses a fan clutch however it also has a electrical connector on it. Look closely at the very front of the clutch you will see wires and the connector is on the upper drivers side of the fan shroud. If you remove it the check engine light will be on. Yes you may get some gas mileage improvement but it will be very minimal. I would suspect less than 1 min per gallon.

MDTAHOE

Cooling System Description and Operation

Cooling Fan Control
The purpose of the Electro-Viscous (EV) fan clutch is to maintain powertrain cooling requirements. The Powertrain Control Module (PCM) monitors the following sensors to regulate the fan speed;


Engine coolant temperature sensor
A/C refrigerant pressure sensor
Vehicle speed sensor
Intake air temperature sensor
Transmission fluid temperature sensor
Ambient air temperature sensor
The PCM controls the electro-viscous fan clutch engagement. The PCM regulates a 12-volt pulse width modulated signal (PWM) to the cooling fan relay. The PWM signal determines the ON time of the relay. As the commanded state of the fan clutch increases, so does the ON time of the relay. This ON time directly effects the amount of time the solenoid, which is internal to the fan clutch, is energized. When the solenoid in the fan clutch is energized, it opens the spring loaded valve and allows fluid to flow from the storage chamber to the fluid coupling of the cooling fan clutch, increasing the fan speed. When the solenoid is de-energized, the spring loaded valve closes, and blocks the path of the fluid to the fluid coupling of the fan clutch, reducing fan speed.

The fan has the ability to create a feedback signal, so the PCM has an actual fan speed input. This is done with a hall effect sensor internal to the fan clutch.

The PCM supplies a 5-volt reference and a low reference to the hall effect sensor. The hall effect sensor returns a signal pulse through the cooling fan speed signal circuit in response to the reluctor track passing by the magnetic field of the hall effect sensor.

The PCM commands the cooling fan to 100% under the following conditions:


Engine coolant temperature exceeds approximately 129°C (264°F).
The transmission oil temperature exceeds approximately 151°C (304°F).
A/C refrigerant pressure exceeds 1655 kPa (240 psi).
When certain DTC's set. These include P0116, P0117, P0118, P0125, P1481, P1482, and P1484.
The scan tool can engage the cooling fan clutch. This is done with the engine controls special function menu screen. To engage the cooling fan, It can take up to 2 minutes for a 100% command with the engine at 2000 RPM. The lower the engine speed, the longer it will take the fan to engage. To disengage the cooling fan, it can take up to 2 minutes with the engine at 2000 RPM . The lower the engine speed, the longer it will take to disengage. In lower ambient air temperatures the cooling fan will engage in less time, however, it will take longer to disengage due to the properties of the fluid vs. temperature.

Under certain conditions the cooling fan may be engaged at engine restart. They are as follows;


The cooling fan was engaged at the time the engine was turned off
The fluid may bleed from the storage chamber into the fluid coupling of the cooling fan
Although the fan is commanded off at this time due to a cold start condition. This is the most likely time a vehicle driver will notice that the fan noise is excessive compared to normal engine starts with out cooling fan engaged. As the engine speed is increased the fan noise will be louder than before. These are normal conditions that can be very intermittent.

01sleeperZ

"The fluid may bleed from the storage chamber into the fluid coupling of the cooling fan
Although the fan is commanded off at this time due to a cold start condition. This is the most likely time a vehicle driver will notice that the fan noise is excessive compared to normal engine starts with out cooling fan engaged. As the engine speed is increased the fan noise will be louder than before. These are normal conditions that can be very intermittent."[/quote]




Thanks for the input! This explanation gives me more details than I have gotten from Chevy sense I got the vehicle new in 02! Now I know why it has the loud fan at cold weather starts, which is accompanied by a noticable lower power level for the first 1/2 mile of driving. I assumed that this power loss was due to the fan and so would help milage if I went to an electric fan. It sounds like it would work fine with a kit that kicks on with an adjustable thermostat and a tie-in to the airconditioner, but will be a big hassel to get the car to work with it and not set a lot of trouble codes. I wonder if it is worth it!

Thanks!