Problem with fan turning on
Problem with fan turning on Hey whatsup everybody. I'm getting my new motor built. The reason its getting rebuilt is because of it overheating one day in the summer because the fans failed to turn on. Now this is a problem that happens once in a blue. It happend to me another day when I turned off the car came back two minutes later and turned it on again. the temp skyrocketed. i turned the ac on and the fans kicked in and the temp dropped. so now that im doing my rebuild i don't want to have a problem with the fans not turning on again and damaging the motor. my question is do you guys think there is a problem with the fan relay? and why would this only happen once in a blue?
On The Tree
Joined: Mar 2008
Posts: 101
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From: naples fl
The Fans Are Not Coming On Because The Pcm Is Not Sending The Ground Signal The Relays. It May Be An Internal Pcm Or A Break In The Harness. If You Want A Cheap Fix Pull Out The Relay Box And Provide A Constant Ground Signal To The Relays. This Can Be Better Then Having A Manual Fan Control Switch That I Have Seen Being Sold For These Cars. When I Worked For Gm I Remember The Fans Coming On Around 215-220 Deg F. If You Do This Mod The Temps Will Stay Around 180 Deg With A Stock Thermostat. If You Have A 160 Deg Thermostat Expect Temps To Be Around 170-175. The Feature Is Almost Like The Fan Control Option That You Get When You Use A Hypertech Programer. Caution!!!!! You Did Not Mention To Me That You Checked The Pcm For Codes. You May Have Something Else Going On Too. Ifyou Are Not Sure What Wires To Ground Out Get A Repair Manual From The Parts Store That Has Wiring Diagram. I Have Done This Before And Does Not Stop The Ac System From Working On 1994 F-bodies. 1995 And Up Is A Different Story Since They Use 3 Relays.
I re-wired the whole complete Fan Circuit on mine..isolated both of them with 2 Switches..ran the Wires for the Relays right through the Fire Wall under the spot where the Main Wires to the Interior come in.
It's not that hard to do..just remember to turn them on.
It's not that hard to do..just remember to turn them on.
The Fans Are Not Coming On Because The Pcm Is Not Sending The Ground Signal The Relays. It May Be An Internal Pcm Or A Break In The Harness. If You Want A Cheap Fix Pull Out The Relay Box And Provide A Constant Ground Signal To The Relays. This Can Be Better Then Having A Manual Fan Control Switch That I Have Seen Being Sold For These Cars. When I Worked For Gm I Remember The Fans Coming On Around 215-220 Deg F. If You Do This Mod The Temps Will Stay Around 180 Deg With A Stock Thermostat. If You Have A 160 Deg Thermostat Expect Temps To Be Around 170-175. The Feature Is Almost Like The Fan Control Option That You Get When You Use A Hypertech Programer. Caution!!!!! You Did Not Mention To Me That You Checked The Pcm For Codes. You May Have Something Else Going On Too. Ifyou Are Not Sure What Wires To Ground Out Get A Repair Manual From The Parts Store That Has Wiring Diagram. I Have Done This Before And Does Not Stop The Ac System From Working On 1994 F-bodies. 1995 And Up Is A Different Story Since They Use 3 Relays.
On The Tree
Joined: Mar 2008
Posts: 101
Likes: 0
From: naples fl
I DONT UNDERSTAND THE PART OF "i changed the constant a while back when i got my 160 thermo.' DID YOU TRY NEW RELAYS? DO YOU HAVE 2 OR 3 RELAYS? IF YOU HAVE 2 RELAYS SIMPLY CUT THE GROUND SIDE OF THE RELAY
CIRCUIT AND CONNECT IT WITH A NEW WIRE TO THE GROUND POST ON THE UPPER RADIATOR SUPPORT THAT WAY WHEN YOU TURN THE IGNITION ON, THE FAN WILL NEVER SHUT OFF AND YOU WONT HAVE TO RUN WIRES THOUGH THE FIRE WALL AND USE A SWITCH THAT YOU MAY FORGET TO TURN ON. YOU WILL ALWAYS HAVE POWER ON THE RELAY CIRCUIT WHEN YOU TURN ON THE IGNITION. ITS THE PCM THAT WILL GROUND OUT THE RELAY SO IT CAN SEND POWER TO THE FANS. THEY ARE THE SMALLER THEN THE WIRES GOING TO THE FAN. MAKE SURE YOU LOOK AT A WIRING DIAGRAM SO YOU DONT MIX UP THE WIRES.
CIRCUIT AND CONNECT IT WITH A NEW WIRE TO THE GROUND POST ON THE UPPER RADIATOR SUPPORT THAT WAY WHEN YOU TURN THE IGNITION ON, THE FAN WILL NEVER SHUT OFF AND YOU WONT HAVE TO RUN WIRES THOUGH THE FIRE WALL AND USE A SWITCH THAT YOU MAY FORGET TO TURN ON. YOU WILL ALWAYS HAVE POWER ON THE RELAY CIRCUIT WHEN YOU TURN ON THE IGNITION. ITS THE PCM THAT WILL GROUND OUT THE RELAY SO IT CAN SEND POWER TO THE FANS. THEY ARE THE SMALLER THEN THE WIRES GOING TO THE FAN. MAKE SURE YOU LOOK AT A WIRING DIAGRAM SO YOU DONT MIX UP THE WIRES.
Last edited by alaureano; Apr 1, 2008 at 07:33 PM.
meant to say that i programmed my fans to turn out earlier with tuner cats. when i got my 160 degree thermostat i went into the tables in the pcm that control at what temp the fans turn on and set it lower so that the fans come on sooner.
