Fans kick on at 208 degrees and off at 199. They kick on immediately with the air conditioning like they should. Last time this happened it was the radiator fan switch (mounted vertically on driver side of intake) so I replaced that first. No change. So then I put in an old coolant temp sensor that was working when I removed it 3 years ago (mounted horizontal on driver side of intake). Still no change. Fan motors and relays must be working if fans are coming on, correct? Connector to coolant temp sensor has 5 volts. I think the radiator fan switch connector had 12 volts if I remember correctly. Any suggestions? The thermostat is 185 degrees.
Fans kick on late
- Thread starter GNRick
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low speed relay is dead and your running on the high speed relay triggered by the switch on the intake
ac commands the high relay thats why it runs with ac engaged
ac commands the high relay thats why it runs with ac engaged
From Vortex Buick page:
For the high speed circuit, ground the dark green/yellow wire. You can do this by pulling the wire connector off the fan temperature switch and grounding it, or by pulling the connector off the pressure switch and grounding the dark green/yellow side. If the fan runs when grounding this side, then the relay is good. If the AC is properly charged, the fan should run on high when the AC is turned on. If the fan runs when grounding the wire, but, not when turning on the AC, then the pressure switch is probably bad. Normally, I believe the fan coolant switch closes at a temperature over 200 degs. As I recall, the book claimed the turn on temperature for the switch is 228 degrees, but, others have reported that the switch may activate as low as 203 degrees with the book being in error. Therefore a car with a good cooling system may never get hot enough to turn the fan on to high speed unless the AC is on.
For the high speed circuit, ground the dark green/yellow wire. You can do this by pulling the wire connector off the fan temperature switch and grounding it, or by pulling the connector off the pressure switch and grounding the dark green/yellow side. If the fan runs when grounding this side, then the relay is good. If the AC is properly charged, the fan should run on high when the AC is turned on. If the fan runs when grounding the wire, but, not when turning on the AC, then the pressure switch is probably bad. Normally, I believe the fan coolant switch closes at a temperature over 200 degs. As I recall, the book claimed the turn on temperature for the switch is 228 degrees, but, others have reported that the switch may activate as low as 203 degrees with the book being in error. Therefore a car with a good cooling system may never get hot enough to turn the fan on to high speed unless the AC is on.
turbobitt
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Does the quad driver control anything else except for the fans?
Yes the serial data line to the ALDL goes through the same quad driver in the ECM. The ECM only controls the low speed fan. It does not control the high speed fan at all. The high speed fan is controlled by the temp switch on top of the intake manifold or the AC pressure switch.
I replaced the ecm and no change. Went for a drive and confirmed the torque converter was locking up. The fans are Spal. They are wired together so both come on together. After I shut the car off, I turned the key to on (engine off) and the fans came on. Temperature was 203. I then pulled the wire off the radiator fan switch and the fans shut off. So I know the wire is good and the connection to the switch is good. I'm going to replace the fan switch again and see if I got a bad one. It's an AC Delco from Rock Auto. Any more ideas?
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read the vortex article
the swittch is for high side you can replace it as many times as you want and its not going to do jack about the low side control not functioning
above 168 do you have power at the fan connector pin A (pin A is from the low speed relay)
PS
also first were hearing of the fans being spal so now my guess is you friked up the wiring to the fans and have them wired to only run on the high side relay
the swittch is for high side you can replace it as many times as you want and its not going to do jack about the low side control not functioning
above 168 do you have power at the fan connector pin A (pin A is from the low speed relay)
PS
also first were hearing of the fans being spal so now my guess is you friked up the wiring to the fans and have them wired to only run on the high side relay
Lil Truck
I spend to much time here....
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Check the connection at the resistors for the low speed.
Found the problem. Blew a 30 amp fuse in the Racetronix harness. So I let the car idle about 15 minutes and my scan tool showed 186 degrees the whole time. The stat is 185. Fans never shut off. Do you think I should have the chip burned to have the fans turn on at 190 and off at 186? Seems like the fans might wear out from running constantly and also is a draw on the battery. Thanks for all of the suggestions btw!
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