E Fans only right fan turning on when A/C is on?

[Richard Payan]

Hi guys so I recently picked up my truck in mexico ans i noticed that only the right fan turns on at full speed when my A/C is on. Its a 2003 tahoe Z71 got an aftermarket harness for it. I already tried swapping connectors and the problem follows any ideas?

 

[Scottydoggs]

could be a bad relay.

 

[Richard Payan]

I have an aftermarket harness so it probably is. Might need to get an OEM one then. Im gonna take a look at it when i get a chance.

 

[mattbta]

OEM harness, with OEM PCM settings turns both fans at same speed, low or high, with a pin for each added to the PCM from harness. Not sure which aftermarket one you have and how your PCM is tuned, but here's the OEM settings from a 2005 Silverado. Obviously, the ECT temps are way high for activation so I have mine lower.

 

[Fless]

Mark the fan relays so you know where they were originally, then swap them to see if the issue follows.

 

[Richard Payan]

guys so i finally got the OEM harness pre installed and it is still doing the same thing but now sometimes i unplugg the fans and swap them and the problem does not follow it does either or, also when I disconnect the ground cable and the power cable and leave it like that for a few minutes and then connect them both fans tend run in the low settings then a few seconds in the same problem continues. Im starting to think its the ECU maybe?

 

[Scottydoggs]

im guessing you bought the truck with the efan swap on it already? if so it could be a tuning issue.

 

[Richard Payan]

im guessing you bought the truck with the efan swap on it already? if so it could be a tuning issue.

No when i got the truck it had the original fan clutch. Im the one that took it to get tuned. I put everything back to the way it was I need it to be more reliable.

 

[Scottydoggs]

No when i got the truck it had the original fan clutch. Im the one that took it to get tuned. I put everything back to the way it was I need it to be more reliable.

kinda seems like a tune issue still. what happens if you pull the plug off the temp sensor. its in the head up front end driver side. both fans should come on full speed with it unplugged. if they do both relays and wiring are working.