Having a bit of an issue, I just installed a set of 05 efans and 34 inch rad in my 99 sierra, added the blackbear tune and had the fans turned on in the tune and used the BB single pin ac/tap harness.

got it all buttoned up and on defrost the fans kick on and off every 15-45 seconds, i understand on defrost the a/c condenser is used to dry out the air and it should kick on, but the consistant on and off seems to be weird to me. gut feeling says it should stay on for a bit then kick off, not off/on off/on consistantly.

any ideas guys ?

 

Low freon causing the compressor to cycle possibly.

 

How long does the compressor/fan stay on for? Perhaps there is a wiring issue and the AC compressor signal is getting shorted out.

 

i have the same problem. Have a single pin blackbear harness with dual electric fans. Had the fan activated in the tune but justin with blackbear said I need an 02+ ecu update to correct the constant on/off as well as the fans always being on while stopped.

 

Mine was constantly going into high speed mode aswell when the AC comp would cycle.
Got sick of it and installed a 212 temp sensor in rad hose to turn fans on high only when needed.

So much quieter now! dont have to turn off AC when at a drive through anymore, Flexlites are LOUD when on high.

 

Ezdaar where did you get your sensor? Was gonna do a 180 degree corvette fan switch but dont feel like tapping my water pump with a 3/8 pipe tap.

 

Frig, some good leads here, the fans are cycling its just far too often, its cold here in the mornings -16 today and i usually leave the defrost on when i park it, so when i remote start it in the mornings to warm it up the fans are constantly cycling and it wont warm up, if i shut the heat off completely the fans stay off and the gauge comes up to temp in the normal amount of time, basically i feel theres an error or its confused as to keep the fans off or on. I just cold started it with the defrost on and the fans kicked off and on 6 times in a minutes time. Justin from Blackbear updated the tune to the 02 up settings.

 

Did you do the ac tap into the ac clutch signal wire?

 

Yes absolutely, as per the insrtuctions.

 

I had mine hooked up like that and had to change it.. my fans would cycle pretty quick too depending on the outside temp and humidity.. all you need for the ac tap wire is a power source to that wire.. so i have mine wired up to a switch in the cab so i can cut my high speed fans on when i want to.. but then if the coolant temps reach a certain temp or my ac pressures reach the desired pressure my low speed and high speed fans will still cycle on by the pcm.. but by me having the switch in the cab i can also cut my high speed fan on when i want..