Question about 1996 GMC Sonoma

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My fan does not blow any air in either heater or a/c how do you replace switch or solve problem

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  • 2 more comments 
  • lforsg Apr 04, 2011

    john, i checked my wiring to my fan motor and it looks like the motor is b.o. what is best way to get motor out? the screws holding cover on are some wierd size i got the top two out but need some advise for the rest.

  • lforsg Apr 04, 2011

    john, my email is about tht fan motor

  • lforsg Apr 04, 2011

    john, i recieved the down loads, have to wait for wife to show me how to retrive them. just and old dinosour and dont know much about computers. thanks i will let you know about progrese tomarrow. Lamar

  • lforsg Apr 05, 2011

    john, job is complete and succesful on the fan motor. thanks for your help. lamar



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First we have to find out if the problem is a power or a ground problem.

at the blower motor , witch is under the hood in the passenger side, you will find a 2 wire plug in, one wire will be purple the other black, with the key on and the blower turned to high you need to check the purple wire for 12 volt, and the black wire for ground, if the purple wire has 12 volt and the black wire has ground then replace the blower motor.( to test for 12 volt power you will need a 12 volt test light hook the clamp to the negative battery post and touch the prob to the purple wire the light should light up )

if the black wire does not have ground then check were the wire mounts to the back of the cylinder head on the passenger side. ( to test for ground you need a 12 volt test light hook the clamp to the positive battery post and touch the probe to the black wire the light should light up).

if there is no power at the purple wire, then you need to check the #6 fuse in the instrument panel fuse box it will be a 25 amp fuse, also check the fusible link at the starter, it will be one of the little wires coming from the large starter post. the best way to check the power circuit is at the blower motor relay it is in the under hood fuse/relay center, remove the relay and turn the key on and make sure the fan switch is in the high position, then with your test light probe the terminals at the blower motor relay, yiu should have3 that have 12 volt if you look at the bottom of the relay plug in you will be able to see the wire coolers, the 3 that should be hot are the dark blue, red, orange the black one should be ground and the purple is the output wire to the blower if all is as should be then replace the relay.

if there is no power at the red wire repair the fusible link at the starter, if no power at the orange wire check fuse #6 if fuse is ok replace the blower switch, if no power at the dark blue wire and fuse #6 is ok then replace the blower motor resistor.( it is mounted next to the blower motor) if no ground then check were the wire mounts at the back of the passenger side cylinder head.

Good luck

let me know if there is ant thing else i can do for you.

Posted on Apr 04, 2011

  • 2 more comments 
  • john nail
    john nail Apr 04, 2011

    screws should be 9/32" the best way is to use a 1/4" ratchet and 10" extension ann a u-joint after removing the screws you will need to rotate the motor abpot 60 degress then pull it strate out you will need to remove the overflow bottal in order to get the motor out. send me your e-mail and i will send you the step by step from the repair manuel.

  • john nail
    john nail Apr 04, 2011

    just sent the info please let me know when you get it ....thanks

  • john nail
    john nail Apr 04, 2011

    OK have fun

  • john nail
    john nail Apr 05, 2011

    your welcome



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