Jake Guzman

I have a 95 z28 I've sorted out all my transmission issues ii just have a question. My cooling fans won't work because I don't have freon in the system and Im aware of that. They work when there's freon in there but it all leaked out. If I buy a SLP fan switch will I need freon in the car or Will it work on its own.

bobdec

Lack of refrigerant will NOT prevent fan from normal operation. AC pressure will run the fans, but only when pressure is there. Here is a test .. with key on engine OFF short pins 5 and 6 together in the ALDL connector. Here is a PIC http://shbox.com/1/DLC_wiring.jpg make sure you use the 1995 diagram. That will light the SES indicator, run the fans. (Also picks AC clutch, EVAP solenoid, EGR solenoid, and air pump relay). If the fans do not run then check the fan fuse, if OK then swap the three fan relays with the air pump, fog light and ac relays. If still no fans swap everything back and let us know. Good luck

Jake Guzman

Whenever I put refrigerant in the fans could come on when they were supposed to. The relays and everything are good I've been through all the. Trouble shooting just replaced temp sensor relays and fans. I just want to know if I get a fan switch will I need air pressure in the system

Injuneer

The fans come on for three specific reasons:

1 - The A/C or defroster (which uses the A/C) is running - fans come on at low speeds

2 - The A/C or defrost is not on, but the coolant temp has reached 226*F (low speed), and they will switch to high speed if the coolant temp reaches 235*F. Are you saying that the coolant temp is higher than these temps, and the fans do not come on?

3 - Certain daignostic trouble codes cause the fans to come on, but that is obvioulsy not relavent to your issue.

The key question is.... how hot is the coolant getting?

shoebox

No a/c pressure needed for fan operation via temp control or external switch. The reason the fans come on with the a/c is to make the a/c perform better.