fan problem

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  #1  
Old 07-14-05, 09:45 AM
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fan problem

I have a 91 van pontiac transport . the fan doesn't work quickly, sometimes it doesn't. sometimes if I turn on the AC it works. I suspect that this pb has something to do with a sensor...I m not sure. Anyway I am thinking of a way to make the fan work directly each time I start the car so I dont worry about overheating of the engine. please do u have any idea how can I do this ?
 
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  #2  
Old 07-14-05, 12:56 PM
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Unplug the fan and run 2 jumper wires from the battery to the fan, if the fan is working unhook the jumpers and run two wires into the cabin from the fan area. Get a switch and run those wires to the switch, connect one to each side. Then run a ground wire from the fan to the chassis. Now you have a switch in the van and you can turn it on whenever you please.
 
  #3  
Old 07-14-05, 01:08 PM
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Not the best advise to hot wire it. First of all your switch would melt fairly quick from the amperage draw of the fan, second the fan motor will burn out in no time flat. The motor trying to turn the blades at the speed the air is coming in put a big load on it. Two things cause that fan to run, one is coolant temp and the other is A/C high pressure. Just because you have the A/C on does not mean the fan should be running. Next time it won't run and the air is blowing warm or the temp gauge is almost to the red line take a long extension and tap the fan motor or give the blades a little spin and see if it tries to run. If so the brushes are worn out in the motor and it needs replaced.
 
  #4  
Old 07-14-05, 02:30 PM
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Definitely not a good idea to give the blades a little spin. It the fan does start to run while your fingers are in it, you'll lose them or if you're using a tool, it could break or break a fan blade that would become a projectile, possibly coming right toward you at high speed.

If you use the switch idea, be sure to install an inline fuse on the 12V wire of the same amperage as is currently used.

Have you actually seen the fan not working when the temperature is hot? By design, the fan should cycle on and off. Not sure if your fan should ever turn off if the A/C is on.
 
  #5  
Old 07-14-05, 05:55 PM
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Your G.M. temp switch, which turns on the fan, does not kick in until the engine reaches 230 degrees F (110 C). If it should fail and not kick in, you will get a temp warning light on the instrument panel.

The fan should always run when the air compressor runs, which is constant on that model. It does not cycle on and off like some others.

Relax and enjoy the ride.
 
  #6  
Old 07-14-05, 06:24 PM
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To Jeff and Goldstar

First I never said to spin it with his fingers. Secondly you can get to the blades without endagering yourself with a long extension. That motor does not have enough torque to break blades. Yes you have to be careful, but just use common sense. Now I am looking at alldatas wiring diagram and yes there is a high pressure switch for the A/C to turn the fan on, it sends the signal to the ECM to activate the fan relay. The fan does not run all the time with the A/C on, the ECM determines when it is needed. eg. at 60 mph the fan is not needed so if head pressue get to high the pressure cutout switch on the back of the compresor removes the ground from the circuit and the compressor is disengaged, if at low speed or idle the head pressure rises the fan is commanded on by the ECM which turns on the fan relay.By turning the A/C on and reving the engine to about 1500 to 2000 rpm a simple tap on the back of the fan motor will probally make the fan try to spin. if this is the case it just needs a new fan motor.
 
  #7  
Old 07-16-05, 07:01 PM
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I had an old VW GTi that had the same fan problem you spoke of, and I did exactly what easywing suggested. I hot wired a switch into my interior, and whenever I wanted to I could switch on the fan. I also raced autocross with
this car so it became very handy. Hope this helps.
 
  #8  
Old 07-16-05, 07:19 PM
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Unplug the temp sensor connector after the engine is hot with a/c off. If the fan starts up, then replace the temp sensor.

If the fan does not start up, then jumper the connector to see if fan starts. If it does, then replace the temp sensor.
 
  #9  
Old 07-16-05, 07:44 PM
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Originally Posted by Toyota_Doctor
I had an old VW GTi that had the same fan problem you spoke of, and I did exactly what easywing suggested. I hot wired a switch into my interior, and whenever I wanted to I could switch on the fan.
I'm a little curious - why would a "technician" recommend hot-wiring an electronic fan specifically designed to run only when necessary within a given temp. range based on sensor input? The ECM controls many drivability functions based on engine temp. You should know that. Even more questionable since repairing that system correctly (if there is even a problem - hard to discern from the description) would be less labor and likely the same or less in cost than hot wiring a switch in.
 
  #10  
Old 07-16-05, 11:41 PM
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I was just speaking of a similar instance where I had to do that to my vehicle. I raced it, it got hot very quickly, and you know how VW's of yester year were. Pretty un-realiable. I figured my little fix was the right one in my situation, and was posing a suggestion to simpleguy for an easy fix. I ran an in-line fuse, so that I minimized the chances of burning my fan motor.
I knew that if I didn't have control of my fan thermal breakdown would devestate my oil, and leave me with no engine. In my opinion I think I made the right repair. Now this was my vehicle. If a customers I might suggest what I did, or further diagnose the situation.
 

Last edited by Toyota_Doctor; 07-17-05 at 06:07 PM.
  #11  
Old 07-17-05, 12:13 PM
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As I live in NYC and encounter traffic with a capital T I have hot wired every car I've ever owned with a cabin switch so I can control the action of the fan. In cars I've owned that had not had this switch I have encountered driving under very hot conditions where my oil would burn. I did leave out on my initial message to also instal an inline fuse but I still think it's the way to go. When traffic starts to get heavy I throw the fan switch and can run the A/C and still be stuck in traffic with no problem.
 
  #12  
Old 07-22-05, 06:45 AM
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thaks

Thank you all for your help and suggestion that gave me a lot of ideas. However trying to check if the fan works I found out that the wires don't connect well to the outlet of the fan so I fixed it now. I hope that was the only problem

just another question, I like to learn more about fixing cars, do u know any
online courses or lectures that offer practicle skills

thank u all
 
  #13  
Old 07-22-05, 07:32 AM
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Most online and offline courses charge a heafy fee. However, many automotive sites offer free advice on basic car repair.

If you have never bought a $15 Haynes manual, then by all means, start there. Get one for your car and it will have a wealth of basic and detail information for anyone with the desire. After that, the learning never stops.
 
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