cooling fans
 

Need some advice. My cooling fans are on all the time. I just installed a new upper radiator hose after the old one squirted fluid all over the engine. My radiator neck is also breaking apart seems as though its rotting. I put a 13lb. radiator cap on last week because the old one was leaking, now everything is fine but the fans could there be a short from the coolant shower?or a bad sensor if so where?

I'd check the ECU to see if there are any trouble codes first.
Are you running the A/C? I think having the A/C running automatically kicks on the second fan
There are definitely temperature sensors that "close the loop" on the cooling fans.

they start running as soon as the car is started, no A/C they just run constantly I thought it might have been an air pocket or a stuck thermostat so i changed the coolant installed a new thermostat bled the system and their still on. The cooling sysstem is working just fine pump is ok. I'll check the codes in the morning I could still use info on the sensors pics if possible. thanks

Hi Mike,

The fans are controlled by four relays which you will find in a separate block to the rear of the distribution and fuse assembly beside the battery. They are numbered front to rear 1 -4 with 4 close to a fuse assembly, all this presuming LH and RH drive cars have the same arrangement.

Relay 1 grounds all fans, 1& 2 control the left hand fan and 4 the RH fan.

Remove the fuses one by one and note if and when the fans stop and report back here for more assistance. :)

I pulled the fuses & relays, heres what I got.

sorry for the lousy pic

Great work Mike,

If every one with a problem came up with that sort of info life would here would be a piece of cake !

You have a short to ground. The fans are controlled all at once by opening the negative circuit to ground via relay (1) (Fan Ground) and removing this should stop all fans. It does not, as you have proven !

Somewhere, somehow, the negative wire from the fans, it can be any one as they are all connected in parallel, or the return wire to the relay assembly, is making contact with the body/chassis and as a result providing a negative return circuit without the fan relay being closed.

P.S. If not the actual wire, a connection terminal or plug may be some how shorted to ground by something which should not be there.

See what you can find and again report back. :) :) We WILL fix the bugger :D

Could one of the relays have a short to ground? (Detective Trevor :))

No.

But taking what is possible to the extreme there could be a short to ground within the relay and fuse mounting assembly. Nothing indicates such a short.

You say the fans stop when you have removed the only relay in the negative and ground circuit. All the others are in the positive circuit. I gave all of this very serious thought before suggesting what you should look for.

Trevor, :)

Is there anyway to hook a switch into one of those relays to turn the fans on manually? I am thinking about doing this to provide forced cooling when the engine is turned off on hot days.

Yes and there are several ways of doing this. Three separate control circuits are involved. Without looking at the wiring diagram I would say that a triple pole switch or a single pole switch together with a network of three diodes or a triple pole relay would be required.

The existing wiring would have to be broken into with tap on connectors close to the fuse/relay assembly or closer to the fans.
It would be a good idea to fit delay release timer to keep the fans on for a set time after the ignition is turned off.

All that said I am not convinced that this would be worthwhile as without the water pump running the only cooling circulation would be as a result of thermo siphon effect and this would quickly cease.

I can't seem to find any shorts, I did however stumble upon an earlier problem.
If I pull out the fuse for the A/C in the bottom right corner of the fuse box the fans stop, could this be related to my problem. I also checked the ecu for codes and got nothing. I accidently plugged the blue wire into the 1st pin on the diag. plug and got a cycle from the fan: relay clicks fans come on then off and it repeats.

P.S. they stop but do not go back on even when they are supposed to when the A/C fuse is unplugged.

based on your last input I think you should consider an examination of the trinary switch. It is on the right side of the radiator and since you mention a previous radiator problem it could be this switch has malfunctioned - it has a fan control function through the A/C system.

What if the ambient sensor is too close to my tranny cooler?

~After lurking for many months~

Mine did that for several weeks. Was pretty embarrasing at the fast food windows with the fan going all the time.

Temperature sensor was replaced under warranty. That's what they said anyway. Fan thinks the engine is overheated....

Scott