Does it have to fans - 1999 BMW 323 Series

My information shows that the 2001 tahoe uses a fan clutch and does not any electric fan. There could be exceptions, but if this is an add on aftermarket fan, there would be some type switch with a relay or fuse wired in the system. First make sure that the radiator is not partly restricted. Using a inferred thermometer check to see is all the radiator tubes are the same temp. Most of the time, the lower tubes are cooler because they are restricted. Also make sure the fan clutch is good. After driving it and the engine is at running, shut the engine off and watch how many times the fan rotated. It should stop after several revolutions.

Possible bad fuse, relay or switch.

It means you should take your vehicle to a qualified repair shop , at least that's the car makers thought .
A/C Off For Engine Protection
Refer to Cooling System Description and Operation
Cooling Fan Control
The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) or engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood junction block. The ground path is provided at G100.
During low speed operation, the PCM/ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the cool fan 1 maxifuse?® through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation, the PCM/ECM supplies the ground path for the cooling fan 1 relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM/ECM supplies a ground path for the cooling fan 2 relay and the cooling fan relay through the high speed cooling fan relay control circuit. This energizes the cooling fan relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the cooling fan 2 relay coil is energized closing the relay contacts and provides battery positive voltage from the cool fan 2 maxifuse?® on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
Are the radiator fans coming on ? You mite take it an have it checked for DTC'S - diagnostic trouble code's .

Why ? Did you test ? Hook up a scan tool to see if the PCM/ECM - engine computer is reading coolant temp. ? Testing not guessing ? Do you even know how the system works .

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the engine control module (ECM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.
During low speed operation, the ECM supplies the ground path for the low speed fan relay, which is Fan 1 Relay, through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from Fan 1 Fuse 29 through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the Series/Parallel relay, which is the Fan 2 Relay, and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the ECM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. The ECM supplies a ground path for the high speed fan relay, which is the Fan 3 Relay, and the Series/Parallel through the high speed cooling fan relay control circuit. This energizes the Series/Parallel relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the Fan 3 Relay coil is energized, the relay contacts close to provide battery positive voltage from Fan 2 Fuse 33 on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground path. The result is a parallel circuit with both fans running at high speed.
When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 10 mph. This is to prevent a fan from cycling ON and OFF excessively at idle.

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the high speed fan relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
Your best bet would be to take your vehicle to a qualified repair shop !
Relay Driven Dual Cooling Fan Diagnostics

Are you talking about the radiator fan? How hot does the engine get in degrees F? Some makes and models, the radiator fan won't turn on till about 220 degrees F. Check for applicable trouble codes, see if any code that refers to the radiator fan circuit or coolant temp sensor? Some of the national brand auto stores will check codes for free.

Of course, as far as overheating in general, you have the thermostat--water pump and other possible issues. Are you losing coolant?

I couldn't find the plug or wire on the diagram on my online resource, either. The fan must have a cable going to it to operate, somehow, though, I agree.
Engine Cooling Fan Removal & Installation To Remove:

1. Before servicing the vehicle, refer to the precautions at the beginning of this section.
2. Remove or disconnect the following:
   • Negative battery cable
     
     
   • Fan blade/viscous fan drive assembly from water pump by turning mounting nut counterclockwise as viewed from front - threads on viscous fan drive are right hand. CAUTION
     Do not attempt to remove fan/viscous fan drive assembly from vehicle at this time.
     Do not unbolt fan blade assembly from viscous fan drive at this time.
     
     
     
   • Upper fan shroud attaching hardware
   • Upper fan shroud and fan blade/viscous fan drive from vehicle CAUTION
     Do not place viscous fan drive in horizontal position after removal because silicone fluid in the viscous fan drive could drain into its bearing assembly and contaminate lubricant.
     
     
     
   • Four bolts securing fan blade assembly to viscous fan drive.

To Install:

1. Install or connect the following:
   • Fan blade assembly to viscous fan drive.
     1. Torque to: 17 ft. lbs. (23 Nm)
   • Fan blade/viscous fan drive assembly and upper shroud into vehicle
   • Fan shroud retaining screws
   • Fan blade/viscous fan drive assembly to water pump shaft
   • Negative battery cable

Engine Fan REMOVAL & INSTALLATION 3.8L Engines

1. Disconnect the negative battery cable.
2. Remove the radiator upper sight shield.
3. Disengage the electrical connector, then remove the integrated relay control/constant control relay module assembly located on the radiator support.
4. Disconnect the fan electrical connector. Fig. 1: Disengage the fan electrical connector
   
   
5. If necessary, remove the air bag crash sensor.
6. Unbolt the fan/shroud assembly from the radiator and remove. Fig. 2: Unbolt the fan assembly from the radiator
   Fig. 3: Remove the fan from the engine
   Fig. 4: Slide the fan as an assembly up and away from the radiator. Be careful not to dislodge the mounting stud on the left side.
   
   
7. Remove the retainer and the fan from the motor shaft and unbolt the fan motor from the shroud.
8. Installation is the reverse of the removal procedures. Tighten the fan shroud retaining bolt to 23–33 inch lbs. (2.6–3.7 Nm). Tighten the fan shroud retaining nut to 71–106 inch lbs. (8–12 Nm). Fig. 5: Constant control relay module location — 3.8L engines
   

4.6L Engine

1. Loosen the fan clutch-mounting shaft from the water pump hub.
2. Loosen the fan shroud from its radiator mounting and remove the lower hose from the shroud.
3. Lift the fan and clutch assembly and the fan shroud from the vehicle.
4. If necessary, remove the fan-to-fan clutch retaining bolts and separate the fan from the fan clutch. CAUTION
   Closely examine the fan for cracks or separation, to avoid the possibility of personal injury or vehicle damage. To install:
   
5. Assemble the fan and fan clutch. Tighten the retaining bolts to 15–20 ft. lbs. (20–27 Nm).
6. Install the fan and clutch assembly and the fan shroud. Mount the fan clutch shaft to the water pump hub and tighten to 37–46 ft. lbs. (50–62 Nm).
7. Slip the shroud into the lower mounting clips and install the shroud retaining screws. Fig. 6: Fan and fan clutch assembly — 4.6L engine
   

5.0L Engines

1. Loosen the fan clutch-to-water pump hub retaining bolts.
2. If necessary, remove the drive belt from the water pump pulley.
3. Remove the fan shroud upper retaining screws. Lift the shroud to disengage it from the lower retaining clips.
4. Remove the fan clutch-to-water pump hub bolts and remove the fan and clutch assembly and the fan shroud.
5. If necessary, remove the fan-to-fan clutch retaining bolts and separate the fan from the fan clutch. CAUTION
   Closely examine the fan for cracks or separation, to avoid the possibility of personal injury or vehicle damage. To install:
   
6. Assemble the fan and fan clutch. Tighten the retaining bolts evenly and alternately to 12–18 ft. lbs. (16–24 Nm).
7. Install the fan and clutch assembly and the fan shroud.
8. Install the fan clutch-to-water pump hub bolts.
9. Slip the shroud into the lower mounting clips and install the shroud retaining screws.
10. If removed, install the water pump drive pulley and adjust the belt tension; refer to Section 1.
11. Tighten the fan clutch-to-water pump hub bolts evenly and alternately to 15–22 ft. lbs. (20–27 Nm). Recheck the belt tension.

The radiator cooling fan used on the 4.0L engine is
an hybrid fan design. The hybrid fan system consist
of a low speed viscous driven mechanical fan and a
electrical fan.
The hydraulic fan used on vehicles equipped the 4.7L engine, replaces both the electric fan and the engine driven mechanical fan. The hydraulic cooling fan is integral to the fan shroud and is located between the radiator and the engine. The power steering pump supplies the hydraulic fluid and pressure to rotate the cooling fan blade, while the electrical part of the fan is controlled by the JTEC. The hydraulic fan drive (motor) consists of the three major components:
- Steering flow control valve
- Fan control valve
- Two stage G-rotor hydraulic drive
The hydraulic fan and drive is not serviceable.
Therefore any failure of the fan blade, hydraulic fan
drive or fan shroud requires replacement of the fan
module because the fan blade and hydraulic fan drive
are matched and balanced as a system and servicing
either separately would disrupt this balance.

4.9L SFI
SPECIAL SERVICE TOOL(S) REQUIRED Description Tool Number Fan Clutch Holding Tool T84T-6312-C Fan Clutch Nut Wrench T93T-6312-B
Removal

1. CAUTION: The large clutch assembly nut has a right-hand thread and must be rotated counterclockwise to remove it.
   Remove the fan clutch (8A616) from the water pump (8501) by turning the large nut, which is part of the fan clutch, using Fan Clutch Holding Tool T84T-6312-C and Fan Clutch Nut Wrench T93T-6312-B.
   

1. Remove two screws retaining fan shroud.
   

1. Remove the fan blade (8600), fan clutch and shroud.
   

1. If the fan blade and fan clutch have to be separated, remove the remaining bolts attaching the fan blade to the fan clutch
   

5.0L, 5.8L and 7.5L Engines
Removal

1. Remove screws retaining fan shroud (8146) to radiator (8005).
   

1. Remove four screws retaining clutch on water pump hub.
   

1. Pull fan clutch and fan blade off water pump pilot and remove fan clutch, fan blade and shroud from vehicle.
   

1. Remove four screws and separate fan clutch from fan blade.
   

Item Part Number Description 1 8509 Water Pump Pulley 2 57632-S Screw and Washer Assembly, 5/16-18 x .62 Hex 3 8600 Fan Blade (5.0 and 5.8L) 4 8600 Fan Blade (7.5L) 5 8A616 Fan Clutch 6 380288-S2 Screw and Washer Assembly, 5/16-24 x .88 Hex A — 16-24 Nm (12-18 Lb-Ft)