Questions and Answers
Camaro Cooling Fan
Q. Hi! You've actually helped me out before so I figure I'll give ya a try again. The car in question is a 1992 Camaro RS with a 305 TBI.
Problem - fan won't turn on when the temp gets high (though it will go on if I turn the A/C on).
I have already tried replacing both the coolant temp sensor for the ECM and the actual fan sensor. I thought for sure it was the fan sensor, because when I grounded the connector to this sensor with the ignition on, the fan went on. But, when I put the sensor in and hooked the wire back up, no fan at high temp (I did not put anything on the threads either). Also, because the A/C comes on, this eliminates the fan relay, correct? Any ideas or explanations for me?
Thanks for the help!
ChadA. That is a very basic system Chad. There are three things that will switch the cooling fan on, Coolant Fan Switch, A/C Switch and A/C High Pressure Switch. The ECM does not come into play in this system.
When the A/C is turned on, it grounds the cooling fan relay which turns the fan on. When the coolant temperature reaches 238 degrees, the Coolant Fan Switch closes and grounds the cooling fan relay and turns the fan on. When the A/C high pressure side hits 232 psi, the A/C High Pressure Switch closes and grounds the cooling fan relay and turns the fan on.
Since the cooling fan comes on with the A/C, we can say the cooling fan relay is working. That leaves the Coolant Fan Switch and the A/C High Pressure switch. Since the A/C High pressure Switch only comes into play when the A/C is on, we can eliminate that as well.
If you disconnect the wire from the coolant switch and ground it, the fan will run. The wire goes directly from the F terminal of the relay to the A terminal of the sensor. If the engine temperature is over 238 degrees the and the fan doesn't run, it has a bad switch. That's the whole system. If you replace the temperature sensor for the ECM, you will not fix the problem. So make sure you have the right sensor before you replace it.
