2001 3.4L V6 SE Cooling Fans Not Working

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Dane Allen

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Overheating. My cooling fans don't come on when the coolant gets to 220. Both work with A/C and primary fan worked normally until recently but no longer. Just replaced the Coolant Temperature Sensor to see if that was the problem, it wasn't. Checked all fuses under the hood. Heads and intake machined recently, new top end gaskets. Replaced poor performing radiator last week and has made a significant improvement in coolant temperature control, almost don't need the fans. No leaks and new hoses all around. Heater blows hot and keeps the engine from overheating as does running the A/C but without either the temp heats to 220-230 and coolant boils out. What next?
 
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Only thing left is relay and the ECM. Not sure if when you put on A/C if that overrides the relay. You are sure you replaced the correct temperature sensor and it is not defective?
 
melsg5 said:
Only thing left is relay and the ECM. Not sure if when you put on A/C if that overrides the relay. You are sure you replaced the correct temperature sensor and it is not defective?
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Just bought and installed the sensor yesterday, how do I find out if it is defective? On the V6 I replaced the unit next to the thermostat housing on the intake manifold beneaththe plelum. Got the relay and am trying that now, will reply with results.
 
melsg5 said:
read this link and the diagnostic chart, it's for a 99 but may apply to yours also

http://www.justanswer.com/pontiac/5sm27-pontiac-grand-se-1999-pontiac-grandam-3-4l-cooling-fans.html
Click to expand...

Ok, not so great news. I put in the new relay and the fans started right up and it worked...for a while. 20 miles later and I think the relay has burned out because the fans are dead again. For two years the temp never went above one notch over 200 and then went back doen to 200 after a few moments.

The head gasket went bad and I had the top end redone and so, now I am seeing the temp go to 2 and 3 notches above the 200 mark. I figure each notch to be a 5 degree increment so that means it is going up to 215 degrees. Maybe this is normal but this is the first time since having the car for two years that it went to and stayed this high. It does wander between 205 and 215 once I get going.

If the new relay is burned out after a 20 mile highway trip then that can't be good, or a cheap fix...
 
Ok, bad news I think. Replaced the relay and the fans both came on and work for about 8-10 miles. For two years I have had this car and the temp rarely went above the 200 mark and just one notch at that. Then the head gasket went out and I had the top end redone and the radiator replaced. Fans were working up until that point. Auxilary fan went first and the primary went soon after. The relay brought them back for a short time and it appears the new relay has died. Anyone know how to test a relay?
 
that wasnt covered in the diagnostic in post #4?
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The new relay fixed it but only for a short time and I think the relay burned out or something. I will go through the check list again.
 
melsg5 said:
that wasnt covered in the diagnostic in post #4?
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Sorry, I mean how to test the relay module, the little 4 pin box that affixes in the fure panel.

Thank you,

The fans stopped working again and when I got home the temp was what I figure to be 215 (3 notches past 200 degrees) and probably half the coolant drained out onto the driveway from the surge tank pressure tube. What would burn out a relay in 10 minutes?
 
Update - it looks like it is the fan beginning to fail. There was a faint chirping that I couldn't pin down and attributed it to the belt tensioner but I'm told when the fan motors are in mid-fail they start to draw more current/volts/amps whatever and it burns out the relays. What was driving me nuts was that the fan worked with the A/C and also with a jumper on 30 and 86(87? Can't remember). I guess the relays double as a fuse in this situation. I will know for sure and let you all know the outcome after this weekend.
 
the fans going would cause your relay issue glad you found it
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Ok, I am 95% sure the problem is fixed, have driven around town and there seems to be no more overheating. It was one or both of the fans failing and was the source of the chirping noise. I checked all the fuses at first and they were all fine. Replaced the fans and relays but what I didn't know was when I replaced the damaged relays the overload transferred to a fuse and burned it. I discovered this when I went though the fuses again as a last resort. Lesson learned is always go over the fuses and relays multiple times. Thanks for the help!!!
 
exact problem Montana 3.4L

Wow..I could have written your post. A blown head gasket that I had to replace on my 2000 Montana eventually led to both my fans not working after I put the top end back together. I bought a new coolant temp sensor and a new radiator. Didn't solve anything. Today, I bypassed the relays and both fans worked. Tomorrow I will pick up a couple of new relays and see where that takes me. The only difference between my problem and yours is that my fans don't "chirp". Thanks for the help in solving this problem. If the relays do the trick, I won't have to go any further...but, I will keep in mind that I might have to replace the fan motors if new relays burn out.
 
1resume said:
Wow..I could have written your post. A blown head gasket that I had to replace on my 2000 Montana eventually led to both my fans not working after I put the top end back together. I bought a new coolant temp sensor and a new radiator. Didn't solve anything. Today, I bypassed the relays and both fans worked. Tomorrow I will pick up a couple of new relays and see where that takes me. The only difference between my problem and yours is that my fans don't "chirp". Thanks for the help in solving this problem. If the relays do the trick, I won't have to go any further...but, I will keep in mind that I might have to replace the fan motors if new relays burn out.
Click to expand...

And make sure the relays are not in backwards. I don't think mine were but a relative who is an electrics guys says they were. When I checked they looked like they did before so I don't know. Also, when I switched relays I burned a fuse but I don't know when so make sure you keep checking ALL of the fuses each time after your test your repairs. A bad motor will draw too much electricity overwhelming the circuit eventually. Same for bad wires, connections and grounds(also a connection). Good Luck!!
 
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