A while back my car started running hotter than normal in traffic. I did some checking & the passenger side fan wasnt working. I replaced the relay & it started working again. I have now noticed its running hot again, the fan is not working again. Can someone tell me what is the problem,i have no idea. I need to get this fixed as soon as possible,have a 1700 mile round trip to Carlisle coming up. Thanks,Guys.

 

The relays mentioned above switch the fans from serial operation to parallel operation. In the serial mode the fans are serially connected together with 12V split between them so they each only see 6V. This makes them run at half speed. In parallel operation the relays connect each fan directly to 12V so both fans run at full speed. If a fan is bad neither one of them will work on low speed but one will work at full speed. The relays switch between the two modes as described below:
The cooling fan relays are used to control the high current flow to power the cooling fan motors. Both fans operate together. When minimum cooling is required, the PCM energizes CoolFan1(#45) and both fans operate at low speed, since the fans are connected in series through CoolFan2 (#43) and CoolFan3 (#44). When maximum cooling is required, the PCM energizes all three cooling fan relays. The left fan is still powered through CoolFan1, but is now grounded through CoolFan3. The right fan is now powered directly through CoolFan2 and both fans operate at high speed.

Since you got the fan to work previously the fan itself probably isn't bad but you may have a loose connection in the circuit.

Here is the schematic if you don't already have it.



Bill

 

I thought both fans ran when you turn the AC on. The only fan working is the driver side ( left ). Im sure the on points on my car have been changed,its a heads & cam car that has been dyno tuned.

 

I think the left fan is working in the high speed mode only.

 

If that is true then the passenger side fan has a power problem or is bad. You may have to disconnect the power feed line to that fan and test it separately to see if it is bad. Make sure both the voltage supply and ground lines are in good shape.

Bill

 

Even though the right fan ran for a while when i put in a new relay,the fan could be bad?

 

Did a little more checking this evening. Started the car,turned ac on left fan comes on,right side does not. Drove the car at highway speeds,temp at highway speeds 190. Check fans left side fan on,right side off. Did some city driving left side fan on,right side off. Temp gets to 230 left & right side both on,but right side much slower than left fan.

 

Try spinning the right fan by hand (obviously when the car is off and cold). Sounds like the right fan motor is seizing up. If if won't turn then the left will turn at full speed when the fans are in low mode. Switching to high could cause the right fan to blow the fuse or burn the relay if it won't run at full speed.

Peter

 

I can spin the fan with my finger. No resistance at all.

 

OK, jumper power to both fans and see how they work. Sounds like the right one might have a bad ground or just have a bad motor.

Peter

 

How do i do the jumper power to both fans?

 

i had the xact sam prob,start car...turn on a/c,left fan should be on...turn right side with finger (it wont bite) if it starts or not at all then 99% its the fan motor...advance auto parts@ $44(same as gm). 1 hr. install

 

Update: replaced right fan motor,still does not work. Replaced the number 45 relay,fan works at low speed with the left fan.When Left fan goes to high speed right fan quits. what else do i need to look at?

 

Ive checked all the fuses,all seem to be good. I will replace the 43 relay,i sure hope that does it. Im leaving for carlisle next week.

 

Switched relays. both fans work on low speed. On high speed left fan (drivers side) works on high speed, right fan (passengers side) does not work. Same as before. When i was describing the problem before i was laying under the car and describing left & right fan hopefully we were on the same page.
I really appreciate everyones help.

 

I think the problem is fixed. It was a blown fuse,which i thought i had checked. What i did was count 2 fuses up instead of counting 2 fuse slots up on the fuse box. When i realized what i had done ,i found that the number 46 was blown. I want to thank everyone for their input,but i especially want to thank 8vette7 for sticking with me on this problem.
thanks all.

 

8VETTE7 - I'm having a strange problem with my left fan. It doesn't come on intermittently yet when it's off, the right fan continues to run. That seems impossible based on the serial circuit feeding he left fan first.

Any ideas? I'm ready to change the connector since they are notoriously bad but it still doesn't seem logical.

Thx,
Jon