A/C Dual Fan Won't Kick On
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From: Austin/Houaton
A/C Dual Fan Won't Kick On
I have a 91 Z28 T-5 305 TPI that has dual fans (one kicks on by thermostat and the other when the a/c turns on). The one that kicks on with the A/C turns on never does. I have checked the fan (tested with 12 volts and it kicks on fine), a/c is working fine, checked all fuses and relays. Don't know whats left to check. Would like to stay AWAY from wiring it to the other fan and/or hooking up a switch in the dash. Any ideas would help
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ullearn@hotmail.com
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ullearn@hotmail.com
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From: Warrenton, VA U.S.A.
I have a '91 too. Actually, the A/C turn's on both fans. One fan, the passenger side, with a pressure switch in the A/C line (as well as with the coolant fan switch btwn 6/8 cylinders).
The other fan (drivers side) by the ECM, but the A/C will tell the ECM to turn it on too (under certain conditions - e.g. when vehicle speed is less than ~30MPH or whatever).
I'll guess from your post that it is the one not controlled by the ECM. If so, this fan (passenger side) is also controlled by the coolant fan switch located between #6 and 8 cylinders above the starter (as stated above). If you don't have an ohmmeter to check the sensor, remove the single wire to this switch and ground the wire. The right (passenger) fan should come on with the ignition "on". If it doesn't, then I'd start checking the connection(s) to the relay or the relay itself. (You stated the fuse was okay.)
Do a search for "fan" here and in the "General" sections. This subject was covered extensively in the past several months.
The other fan (drivers side) by the ECM, but the A/C will tell the ECM to turn it on too (under certain conditions - e.g. when vehicle speed is less than ~30MPH or whatever).
I'll guess from your post that it is the one not controlled by the ECM. If so, this fan (passenger side) is also controlled by the coolant fan switch located between #6 and 8 cylinders above the starter (as stated above). If you don't have an ohmmeter to check the sensor, remove the single wire to this switch and ground the wire. The right (passenger) fan should come on with the ignition "on". If it doesn't, then I'd start checking the connection(s) to the relay or the relay itself. (You stated the fuse was okay.)
Do a search for "fan" here and in the "General" sections. This subject was covered extensively in the past several months.
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Joined: Jun 2000
Posts: 1,295
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From: VA
Car: '91 Z28
Engine: L98 5.7L TPI
Transmission: 700R4
Axle/Gears: 323's
disconnect the plug on the pressure switch on the a/c and put a paper clip in there to short it and see if it works that way. I'd bet that pressure switch is bad...
KAM
KAM
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From: Austin/Houaton
Could not enough freon in the system cause the fan not to kick on? Since the switch that kicks on the a/c fan is controlled by pressure in the lines, if the system is not fully charged (2.25 lbs or 1.02kg of freon)then perhaps the fan won't know to kick on b/c the pressure is not high enough, any techs out that can tell if this could be true????? The reason I belive this b/c the fan does not kick on when I am just driving the car to and from the store, but it was working fine after a two hour 120 mile trip.
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