Cooling Fan Issue
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Author:  JoeInOttawa [ Fri Apr 14, 2017 3:34 pm ]
Post subject:  Cooling Fan Issue

My rad fan does not come on, and I'm looking for solutions.

As the car sat running in the driveway, it came close to overheating, but the fan never kicked in. I disconnected the connector from the harness to the fan, and here's what I found:

- The sending end (I'll call it the sender :) of the connection has constant voltage between about 5v and 13.2v, and that seems to follow the temperature gauge

- When I hooked the fan side of the connector (the receiver) directly to the battery, it ran fine. The temperature immediately started to drop and reached normal temperatures in just a couple of minutes

- When I connected the fan to a 9-volt power source it ran, and also kept everything at operating temperature

- When I reconnected the two pieces of the connector together, the fan went back to not working

I used wires to connect the one side of the connector to the other, and, while it measured up to 13.2 volts, the fan did not turn, but when I swapped the wires away from the Sender to the battery terminals directly, the fan ran.

BTW, with the car cooled down, I took off the rad cap, and when the car got hot, water did start to flow through the rad.

So I'm stumped. Happy to see it's not the rad, the thermostat, or worse, the water pump, it's definitely something about the fan not running. But what the heck is causing the fan not to operate?







Author:  87paperchuckerTurbo [ Fri Apr 14, 2017 8:01 pm ]
Post subject:  Re: Cooling Fan Issue

Jimmy!!!!! :alien:

So is it a mk1 or 2?

The mk1 has more than one temp sensor either 2 or three ones for the guage. One is s simple switching device that drives the fans.

Find the switching device and test it and then test the wires to and from it. ... lement.pdf
That's the link to the turbo supliment that works for me it shows how to test all of that stuff.

I had to replace my sensor that does the switching to get my fans to work.

If all else fails buy a universal fan switch it allows you to set the temp at which your fans comes on via a probe that pokes into the veins in your radiator you then set it with a small flathead screw driver to come on a little after your thermostat opens or any point at which you want it to. I bought one at knechts for 32. I plan on using one as a air charge temp sensor for a water injection setup(if it will work how I want it to) my friend used one on his 240sx drift missile when his fans stopped switching on on the second race day.

Thank you CJDavE for making that link available to all us team swifter's

Author:  JoeInOttawa [ Fri Apr 14, 2017 9:29 pm ]
Post subject:  Re: Cooling Fan Issue

87paperchuckerTurbo wrote:
So is it a mk1 or 2?

It's a '90, so that makes it a MK2.

It's weird that the wires going into the connector have voltage but the fan doesn't see it. I'll have a look at the trouble shooting in the manual you've provided, maybe I can figure it out from that.

Thanks very much for the reference!


Author:  Woodie [ Sat Apr 15, 2017 4:43 am ]
Post subject:  Re: Cooling Fan Issue

A MK2 what? Probably doesn't matter because the cooling systems were all pretty much the same.

I know on the 3 cylinders, there were four different temperature sensors. The one for the fan should not have a varying voltage that mimics the gauge. The one for the fan is a switch that just turns on or off at about 200° The sensor for the gauge and the sensor for the fan are mounted on the thermostat housing. I'm pretty sure the one for the gauge has one wire. The switch for the fan has two wires, if you jump across them, the fan should turn on. It also goes through a relay in the box by the battery.

Author:  JoeInOttawa [ Sat Apr 15, 2017 8:27 am ]
Post subject:  Re: Cooling Fan Issue

Woodie wrote:
A MK2 what?


It's a 1990 Sprint Turbo.

I'll have a look at the switch sensor -- thanks!

Author:  87paperchuckerTurbo [ Sat May 13, 2017 6:33 pm ]
Post subject:  Re: Cooling Fan Issue

You fix your fans? :)

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