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The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.
During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.
During high speed operation the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the high speed fan relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
Your best bet would be to take your vehicle to a qualified repair shop ! Relay Driven Dual Cooling Fan Diagnostics
Deanna, check to see if your A/C is in the on position, this could cause fan to run a lot. If this is not the case, take truck in for diagnoses at a good shop, could be a faulty heat/fan sensor or sticking relay. Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info." Diagnose Engine Cooling Fan Relay Problem 2007 Chevy Silverado Fans Always Run Engine Cooling Problem 2007 cooling fan running all the time
Sounds like the HIGH fan relay is stuck in the ON position. Pull the relay and see if it goes off. It should. Then simply replace the relay. This relay should be located under the hood, in the black relay/fuse center.
you need to replace the fan resistor located by fan motor if not there then trace red and black power wires to locate resistor behind or under dash it wont be mounted far from fan motor
cooling fan is activate for many reasons like engine hot, A/C high pressure, if there engine code and so on
does check engine light is on?????
hope it helps
Most have a sending unit near the thermostat housing or on the cylinder heads. Ask the parts store which sending unit you need for the fan control. If you change it with the engine cool you will not get burnt by hot antifreeze. Some newer engines run the fans through the computer. I wish they would not change the engineering all the time. Good luck.
i have 2005 chevy silverado 1500 z-71 have problem with cooling fans coming on when truck is cold and staying on until the battery dies. i've changed the cooling sensor and swapped relays, I've also had mechanic put scan tool on truck and said it was between computer and relays. any ideas.
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