MNBlade

iTrader: (20)

Hey everyone, I have a problem that has made me scratch my head for a while now. On my 2006 Grand Prix GXP, bone stock (for now) the radiator cooling fan is not coming on.

I have replaced the Coolant Temp sensor and that didn't change the issue. I have tested the fans with direct power and they do work. If I unplug the temp sensor, the fans will come on but when I plug it back in and turn the car off then restart it, they do not come on.

I know they should come on with the Air Conditioner or defrost, so I tried that but the compresser isnt coming on, neither are the fans.

I'm at a loss as to what to try next. Anybody have a idea what the issue could be?

Thanks

91parkave

iTrader: (4)

did you run through all of your related fuses and and cooling fan relays? since they do work with temp sensor being unplugged we know it cant be the fans themselves.

MNBlade

iTrader: (20)

Forgot to mention that, I did run through all the fuses and relays, they are all fine.

El Cid

Don't know if this will help:

Cooling Fan Control 3.8L and 5.3L

The engine cooling fan system consists of 2 electrical cooling fans and three 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. The ground path is provided at G100.

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 fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage from the fan 1 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 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 PCM supplies the ground path for the fan 1 relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the fan 2 relay and the fan 3 relay through the high speed cooling fan relay control circuit. This energizes the fan 2 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 closing the relay contacts and provides battery positive voltage from the fan 2 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. The 5.3L LS4 cooling fan is not affected by engine speed.

The 3.8L L26 and L32 cooling fan is affected only if the cooling fan is commanded on for A/C pressure. If coolant temperature is commanding the cooling fans on low or high speed, engine speed does not affect the cooling fan operation.

The following are conditions that can affect the cooling fan:

• Engine speed above 49 mph will cancel the A/C pressure high speed cooling fan request.

• Engine speed above 55 mph will cancel the A/C pressure high and low speed cooling fan request.

The PCM commands Low Speed Fans on under the following conditions:

• Engine coolant temperature exceeds approximately 100°C (212°F)

• When air conditioning (A/C) is requested and the ambient temperature is more than 4°C (39°F)

• A/C refrigerant pressure exceeds 1241 kPa (180 psi)

• After the vehicle is shut off if the engine coolant temperature at key-off is more than 117°C (242°F) and system voltage is more than 12 volts. The fans will stay on for approximately 3 minutes.

The PCM commands High Speed Fans on under the following conditions:

• Engine coolant temperature exceeds approximately 105°C (221°F)

• A/C refrigerant pressure exceeds 1655 kPa (240 psi)

• When certain DTCs set

MNBlade

iTrader: (20)

Thanks for the reply. It helps understand it a bit but I am still having trouble finding the issue. Has anyone had a problem like this before?

Ladue2005

Any luck? I'm having the same issuse with my 06 impala ss ! Car x told me that the coolent fan didn't have a ground to it ! They also told me it'll be $105hr to find the problem . All fuses checked out good

superglide9375

u might be out of refridgerant if ac compressed not coming on did u ck that?

Ladue2005

yes the air works but some times it cuts off.. When I turn the air on only one fan comes on .

superglide9375

yea u gonna have to trace the wires for fan that not working all the way to ground as el cid has provided to i believe u have nick in wire grounding itself I'm wondering that it cant be true about no ground to that fan as one fan is working and one isn't which tells me that they have separate grounds ck that and get back to us that won't take long if there was only one ground both of them wouldn't come on,I'm my opinion

Ryan Robitaille

If your fans turn on when you unhook the temp sensor you were sold a faulty or wrong temp sensor buddy....mine didn't turn on at all car almost overheated unhooked they ran constant....
got proper sensor guess guy sold me one rated for a GTP which they are all different . Fans ran proper ever since