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I need a little help understanding the operation and purpose of the secondary fan in my '92. I thought that this fan should operate if an ECM code is set or certain coolant/oil temps are exceeded and ALSO when the A/C is turned on. However, my secondary does not turn on with the A/C. I'm not sure if this is normal or if I have a problem. Any thoughts would be appreciated.
The picture is from a 93 service manual; i think it´s the same for your 92.
My 93 does not turns on the secondary fan with the AC and all it´s working fine.
In 1991, if you connect the A and B in the ALDL connector and turn the ignition to on (do not start), ECM will turn both fans on. The easiest way to check that both fans do work. (I don't know, if this still works with 92 and up)
In 1991, if you connect the A and B in the ALDL connector and turn the ignition to on (do not start), ECM will turn both fans on. The easiest way to check that both fans do work. (I don't know, if this still works with 92 and up)
If jumpering pins A and B start only one fan, try swapping the two cooling fan relays. They are both the same so if the secondary fan works after swapping the relay and primary fan doesn't, get a new relay.
Also make sure the A/C is working properly. Issues like low pressure may not turn on the secondary fan.
If jumpering pins A and B start only one fan, try swapping the two cooling fan relays. They are both the same so if the secondary fan works after swapping the relay and primary fan doesn't, get a new relay.
Also make sure the A/C is working properly. Issues like low pressure may not turn on the secondary fan.
01-26-2015, 06:20 PM
C-4 Secondary Coolant Fan Operation
