Cooling Fan connections burnt

[RedRat]

Hey guys. 91 Legacy, cooling fans (both) inoperative. Unplugged the connections and the ground wire from the main fan is charred inside the connections housing.

 

Any ideas as to how/why this would happen?

 

The fans both work fine when jumped to the battery. But they don't do squat otherwise. Even if the AC is on. And yes the engine is getting hot enough, as in too hot for my comfort (especially in Seattle traffic )

 

I am in the process of replacing the temperature sensor (the one to the ECU or computer) and checking the relays, but still concerned that there was a burning in the connection which I can't see happening from a bad relay or sensor.

 

Another question, on a side note: does anyone know if the AC fan will work even if the temp sensor is bad? How about if the

AC doesn't work (no freon) Is it supposed to come on anytime the AC is turned on? Like I said, my AC doesn't work, but would the fan turn on anyways?

 

thanks from bellingham, subaru country!

[Cougar]

When connectors get burned like that it is due to excessive resistance at the connector which cases heat to build up when a high current passes through it. The connector may have been dirty or loose. Replace the connector with a new one and make sure the connections are tight.

 

The temperature sensor for the fan is critical so if it is bad then the fan won't turn on. As far as the AC fan goes I think it should still work ok even though the freon is gone.

[RedRat]

That makes sense that the connectors may have been dirty or loose. I did replace both fans a year and half ago when the motors finally died (294k). Very possibly the connectors were compromised then.

 

I just replaced the temp sensor and that didn't change anything.

 

Assuming the new NAPA temp sensor I put in is good I think I am looking at a problem between the temp sensor and the fan. ie a relay or a wire.

 

Tomorrow I will get fresh start and see if the connection from the chassis is getting electricity when the motor is hot. If not, test the relays. If so, well I am going to replace the connector anyway.

 

This is a good job for me because I don't know much about electricity and here is a chance to learn how to properly use a multimeter

 

BTW, does anyone have a lead on those connector housings?

[Rooster2]

That makes sense that the connectors may have been dirty or loose. I did replace both fans a year and half ago when the motors finally died (294k). Very possibly the connectors were compromised then.

 

I just replaced the temp sensor and that didn't change anything.

 

Assuming the new NAPA temp sensor I put in is good I think I am looking at a problem between the temp sensor and the fan. ie a relay or a wire.

 

Tomorrow I will get fresh start and see if the connection from the chassis is getting electricity when the motor is hot. If not, test the relays. If so, well I am going to replace the connector anyway.

 

This is a good job for me because I don't know much about electricity and here is a chance to learn how to properly use a multimeter

 

BTW, does anyone have a lead on those connector housings?

 

The connector housing is best found at a wrecking yard.

 

I am also thinking that simply turning on the A/C, turns on the cooling fan. It is wired that way, and is not dependent on any sensor. So, if refrigerant is low, I think the fan should turn on when the A/C is turned on.

[94Loyale]

No, just turning on the A/C will not actuate the fans. The compressor actually needs to engage in order for the fans to start running. The fans will only run in cycle with the compressor wheel. So without freon in the system to kick the compressor on you won't get any fan action.

[tractor pole]

When connectors get burned like that it is due to excessive resistance at the connector which cases heat to build up when a high current passes through it. The connector may have been dirty or loose. Replace the connector with a new one and make sure the connections are tight.

 

exactly, I would also put some dielectric grease in the connector you use to replace it. this will help displace moisture and keep the connectors from corroding and eventually burning down the road.

[RedRat]

Here's an update, better late than never:

 

A burned connection was the original source of fan failure. During the trouble shooting process I blew the fan fuse and didn't recognize it until after I replaced the temp sensor and was scratching my head at the relay (it tested good so I was stumped). Check those fuses often!

 

A fortunate side note is that the cooling fan relay is in the same area as the blower relay (for the heater/defrost etc) and my heater had just stopped working. So I was right there to replace that relay and get my heater blower running again.

 

One thing I noticed, and maybe this is normal but ANYTIME the

A/C or DEFROST is on my main fan turns on. So at least I have a manual way to switch the fan on in traffic or anytime I feel like it. I don't know if my A/C is charged with freon but I know it doesn't blow cold air. The A/C fan (smaller of the two, passenger side) does engage when the engine is really hot and the A/C or DEFROST is on. So thats cool.

 

With fresh coolant and fresh oil the 91 Legacy is a much happier camper now.

 

Thanks for the help guys!