just bougth 01 Z...runs 190-200 going down the highway but when i got home it was ideling with the ac on and got up to 235ish and it looked like the fan on the drivers side was not on (passenger side was running)...so i went ahead and shut it off...when should the fans engage? this seems too hot to me...what all should i look for...thanks for the info

 

With the key off, I'd see if you can freely turn the drivers side fan to see if the motor feels ok. I believe they should always run together and you may have a bad motor there. If it spins ok, then your electrical trouble shooting begins. 235 sounds a little warm to me too. They have a low speed and high speed, but I do not know at what temps exactly they run those speeds at.

 

When the engine is at temp, turn on the AC. If both fans are running, they are fine. Those temps are normal for the LS1. The fans work independently and at 2 speeds. Under normal load conditions, only one fan will run. When the temps hits another level, the second will run. Now if the AC is on, BOTH fans will run. This is the best way to check if both are working.

Also check for debris underneath by the radiator.

V

 

I beg to differ. Both fans work at the same time. If the drivers side fan is not turning, there is either something physically obstructing it, or a relay is bad.

I agree that those temps are normal. Also, if under 35mph and with coolant above 185deg, turning on the AC does turn on both fans to low speed. Without AC on, low speed fans come on at approx 226deg (temp varies slightly on different model years) and fans go to high speed at 235. They go back to low speed at 226 and off at 219 (unless the AC is on.)

 

Yup, Pilot is correct. BOTH fans work together and have two speeds. From the manual:

The low speed cooling fan is commanded on when the coolant temperature reaches 108°C (226°F). It is turned off if the coolant temperature lowers to 104°C (219°F). The high speed cooling fan is commanded on when the coolant temperature reaches 113°C (235°F). It is turned off if the coolant temperature lowers to 108°C (226°F). When the A/C is on and the coolant temperature reaches 85°C (185°F), the low speed cooling fan will be turned on at vehicle speeds less than 56 kPh (35 mph).

Of course it says "fan" when they mean "fans" as a unit of 2.

 

I believe "low" is accomplished by running the 2 fans in series...if one motor is bad, both won't run. In hi they both get full batt voltage, thru separate relays.

At least thats how most GM cars work....

 

How do you figure that they work together?

1. As temps warm up to 108C, fan 1 comes on. Fan 2 is still off.

2. If fan 1 can control the temp and lower it to 104, it turns off. Fan 2 has never run yet. This is normal operation if its not sweltering outside. Fan 2 hardly ever runs.

3. If fan 1 cant get the temp under control and it continues to rise above to 113, THEN fan two kicks in. Only now are both fans on.

4. If the engine begins to cool now, the fans shut off sequentially. First 2, then 1.

 

I went and checked it. Just came back from store. At temp, both fans came on low speed.

 

Your temps must have hit 113C to activate the second fan, and were still above 108 when you looked under the hood.

 

 

You're right and I am wrong. Saying that makes me a bigger man, doesn't it For what its worth, I really did learn something new and interesting 2day!

From the manual:

The engine cooling fan system consists of two 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 recieve battery positive voltage and ignition 1 voltage from the underhood electrical center. The ground path is provided at G102.

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 cooling fan 1 relay coil, closes the relay contacts, and supplies battery positive voltage 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 3 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 cooling fan 1 relay through the low speed cooling fan relay control circuit. After a three second delay, the PCM supplies a ground path for the cooling fan 2 relay and the cooling fan 3 relay through the high speed cooling fan relay control circuit. This energizes the cooling fan 3 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 on the cooling fan motor supply voltage supply circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have their own ground paths. THE RESULT IS A PARALLEL CIRCUIT WITH BOTH FANS RUNNING AT HIGH SPEED.

 

You're right too...

Damn it all.

 

OK, now we agree that both fans run for both speed we can get back to the troubleshooting then?

Your car got up to 235 because both fans are supposed to come on low at 226 but something is wrong with the low fan speed (drivers side fan motor, wiring, fuse or relay) and the low speed didn't come on.

If you're not sure about the schematic posted then check the following.

Take a couple of wires and jumper power and ground to the fan motor and see if you can get it to work. If the motor is bad and won't run with power applied then you've found the problem. You can also turn on the AC and wait for the temp to reach > 185 degrees and then check the connector for power. If there is power and fan won't run then it's likely the motor.

Check Fuse 39 - this fuse is power for both fans on low speed and drivers side fan on high speed.

The relays Cooling1 = 45 and Cooling3 = 44 are used for the low speed circuit. Try removing the relay Cooling 2 = 43 and replace 1 and 3 with this one to see if the fans begin to work. You could also just swap both the 1 and 3 relays with other relays that are the same size from the fuse box.

Peter

 

Hey, once we're discussing the early 4th gen F-body and likely some C4's as well you'll be right. There were some that did run 1 fan motor at full voltage for low speed.

Peter

 

Good on ya, Peter. This is very logical. Start by making sure the motor is ok, and then work backwards. you could also probe the connectors with a Ohm meter to eliminate the wiring as a problem. If the motor, fuse and relays are good, it might be bad wires or a crappy connection.

 

thanks you guys, yall are great help....drove it yesterday for a few minutes to confirm what i saw....ran 200-220 on the highway with outside temps over 100...let it set in the driveway after i got back to check it....235 with ac on and just passenger side fan was running...i will start chasing electrical issues tonight when i get home...thanks again and i will post my findings

 

ok checked all fuses that said fan...swaped the two relays that had the same part number on them...and nothing...havent tried jumper...but before i quit i found that when you first crank the car the driver side fan will run...but for like 30sec tops then turns off...??? wth...thanks for the input!
chuck

 

ttt...any reason why it would come on then turn off???

 

I had the exact same problem as you... temps rose at idle, a/c got hot while sitting there at idle as well. drivers side fan motor was bad. got it replaced today and all is well again. looks like that may be your problem as well. good luck.

 

I agree.

Look at the schematic posted above. For low speed operation the current flows through the COOLFAN1 fuse, through Relay 45 and then through contact B of the left side cooling fan out through contact A and then through COOLFAN3 Relay 44 to contact B of Cooling Fan –right and then to ground through the A contact of Cooling Fan – Right. Basically in this configuration each fan sees 6 Volts. In high speed operation each fan will see 12 volts.

If the drivers side fan (Cooling Fan – Right) isn’t running there can only be three possibilities; (1) The fan motor has an open circuit, (2) the fan motor is internally shorted, (3) the fan is blocked from turning.

The first and third possibility can be thrown out right away as you have seen the fan turn if even for a short time so it probably isn’t blocked and if the motor circuit was open the right side fan would not be able to run either. That leaves an internal short that initially allows the fan to run for a couple of seconds and then drops to such a low resistance the motor will not turn but allows 6+ volts to be applied to the right side fan thus causing it to run a little faster on the low speed setting. It looks to me like the right side fan needs replacing. If you can pull the fan mount try switching the two fans and see what happens.


Bill