I swapped a 34" rad with some OEM fans (both from a 2007 Tahoe) and an aftermarket harness. Do these fans only turn on if it over heats? I can sit in traffic and my temp stays around 205, 195 when driving. No problems with overheating but the fans have never turned on. Its not a problem, but my trans gets up around 190 when in stop and go traffic. Back down to 130-140ish when driving. Id like to get some airflow through there in traffic. Just curious how they work.

For the harness, I added the pins to the PCM connectors so everything should be good there and its turned on in the tune.

 

who did the tune? They prob set the temp. Factory dont come on till like 215 for fan 1 and like 227 for fan 2

i set mine to come on at 200 and off at 195

 

I agree with this! However if the a/c is on the fans should be running atleast on low speed. I have a 180*F thermostat and have my low fans set to come on at 190 and off at 187. High fan is set for 195 and off at 190.

 

mines are from a 07 silverado with oem harness and when the AC is on one fan turns on on high..i could never see the fans turn on both on low but they do turn on only when its overheating..i unplugged mine once and my trucks temperature increased quickly so the fans are working i just cannot tell when theyre on

 

Swap the harness relay control wires at the PCM. Low fan should turn both fans on low. High fan should energize the S/P relay and Fan 2 relay.

 

heres mine before i adjusted it

 

Thanks guys that helps. Justin is doing my tuning. I will see what he has it set to. I just want to get a little flow going through the trans cooler in traffic, but 190ish isnt too bad I suppose. It was 80* and in traffic for 45 minutes (to go 2 miles lol)

 

Not sure how you have your cooler setup, but my cooler setup is plumbed from the transmission into the radiator, then to the auxiliary cooler, then back to the transmission. The outlet of my transmission cooler has a thermostatic switch plumbed into it that kicks the 8" tranmssion cooler on at 175*F. Both of my low speed fans run in traffic with the a/c on and sometimes bump to high speed.

http://www.summitracing.com/parts/der-13750/overview/

 

with my trucool 40k i have it plumbed from transmission to the rad to the cooler back to the transmission. i never see above 140º ever.

 

190* tran temp is fine, especially in the scenario you stated. If your fans weren't coming on, then nothing would have been as cool as you have stated.