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I have an overheating problem and I've found that my #1 fan that should be coming on at or about 195 degrees isn't coming on. I've checked the fan motor, it's good, I've checked the fuse and relay and they are good. The #2 fan comes on with the air conditioner just like it should. I did find that there isn't any power to the # 30 pin on the relay. Are the #1 and #2 fans controlled through the same temperature sensor? I've replaced the temperature sensor also. Any one have an idea what might be the problem?

  • Welcome tothe site! :) One question, how did you determine that the fan motor was good? Please be very specific about how you made that determination. The reason is I'm thinking bad ground, or the #30 pin on the relay is supposed to be power for the fan. Do you have the electrical diagram for the car? – cdunn Aug 2 '16 at 16:31
  • I connect my fan directly to the battery. I do have a manual. When I test for voltage at the 30 terminal on the fuse/relay panel I should have power all the time. I'm not getting any power. I do get power at pin 85 and I also get power at the 87. There isn't any markings on the relay panel that shows witch connection is #30, I'm using the schematic that is on the relay but the relay can be connected two different ways. I noticed that one corner of the relay is marked by a cut off corner. I assume this mark is identifying the #30 pin. – Ron Aug 4 '16 at 14:21
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Most GM cars will not turn the cooling fan on until 230 degrees or higher. One fan should come on when the ac compressor is running regardless of engine temp, Most of the time the fan relay has failed, failure can be just a tired relay or the fan is pulling too much current due to being worn out which burns out the relay.

Schematic is same for 4 cylinder or V6

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