Left side fan won't turn off. Any ideas?

I believe the left side is controlled by a temp sensor that screws into the top of the radiator...

 

First try swapping the left and right fan relays, in the passenger foot panel. The relay may be stuck "on" and if the problem moves, get a new relay.

If the problem does not move, then I would suspect the radiator thermo switch is stuck on, which is screwed into the top of the left radiator. Not too bad, you jack the car, remove the left rear wheel, and forward fender liner to get to it. Takes 15 minutes.

Thermo switch can be purchased from dealer or Ricambi..there is no cross reference to be found. Make sure you order another fiber washer for it too.

 

bad relay...or temperature switch.

You can diagnose the switch by disconnecting it while the car is running but still cold ---- if the fan shuts off = bad switch.

 

Good posts!

 

There are also problems in that fuse box causing this failure mode and a fan inop situation I have dealt with. After you check all of the suggested routes above and it still doesnt make sense..... it is likely in the box. I have a 97 we are triaging for the short fall driving season to be fixed when the weather turns. This is a less common failure mode of a number of problem areas we have found with the fuse box.

 

Disclaimer: This is probably not an "approved" Dave Helms fix for the problematic 355 fuse box, but I think this may delay the onset of fuse box melt down.

The big problem seems to be the radiator fans drawing too much current as they age. Symptoms are blowing the 30 amp fuses, and when idling in traffic, when the fans come on, the idle drops from the high current draw and parasitic drag from the alternator working so hard. I would suggest at the first sign of this, replace both fans preventitively...don't wait for the problem to get worse. This will not fix our weak fuse panel, but might nurse it along until you can get the Dave Helms permanent fix of updating the panel and moving those circuits off the main panel.

There are plenty of threads on the fan replacement and where to get them for a reasonable cost.

 

Hugh's suggestion on fan replacement is very good advise. If followed it will prevent a number of problems if done early enough. I suggested the same to a number of owners over the last two years... I found it near impossible to sell fans to an owner of a car that is not over heating and the fans operated. I left it at OK... we will deal with it When it becomes a multi faceted problem, it will, it does and it has.

I have identified 4 problems with the 355 fuse box design at this point. There are a number of others that are easy to predict once the circuit is drawn out but it appears in all but the worst cases these can still be prevented. The circuitry has a situation that leads to floating grounds to a number of systems in the event of multiple failures. Understanding and predicting each of these faults is a bit of a puzzle but we should be done soon.

When in doubt, fuse it..... what do you do when the fuse doesnt blow? Photo's I requested sent to me when I started this project a few years ago.
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JM3, you might want to consult with Dave Helms, as I would be suspecting a possible fuse box issue could be the culprit.

 

Hi,
I have the same issue, LH fan is always ON.
I check fuse and relays and they are OK. I also just change the radiator temp sensor and problem is the same.
I disconnect the sensor and use my multimeter, the 2 wires (purple and black) are together. I don't know where i can look now...
Any idea please?
Thanks

 

It could be a faulty pressure switch on the airconditioning receiver dryer. Try disconnecting the connector.

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This also controls the LH fan relay. I don't know if you can access the connector without removing the luggage compartment liner (?)

The two blue wires control the fan.

 

I just disconnect this connector and turn ignition ON : LH fan go ON just after that... problem is the same

 

One more thing : just saw my inside air blower don't work... i dont know if there is something common...

 

Strange. So if you disconnect the both the temp switch and the AC pressure switch, the fan still runs? These devices control the fan relay coil.

Can you pull the relay (with both temp switch and AC pressure switch disconnected) and see if you still have a permanent earth on the relay coil? Use a voltmeter to check for key power either on relay sockets 85 or 86. If 85 is key power, switch your meter to resistance/continuity and see if 86 is permanently shorted to earth.

 

I can't think of anything in common at the moment.

 

If you have an permanent earth on 86 or 85, the only way you can isolate the problem is by disconnecting plugs on the back of the relay panel.

The H plug goes to the radiator fan sensor (switch) and the C plug goes to the AC pressure switch.

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Disconnect the plugs and look for a permanent earth on either H-12 or C-9 (wiring side of the connector, not the relay panel side). If no permanent earth found, the issue may be inside the relay panel

 

For reference... 2.7 fan wiring diagram here:

https://www.dropbox.com/t/4GTeHSQzqbtiugLt

 

Thanks Qavion, i hope i can try this during the weekend.

 

Did you try with both, the thermo-switch and the receiver dryer switch, disconnected?

 

Regarding your blower fan… The usual suspects are:

fan itself
30 amp “hidden fuse”
Power relay
Fan speed controller
HVAC ECU

Unfortunately, most diagnostic work usually involves the removal of the frunk liner, although you might be able to check the 30 amp fuse and power relay by checking power on the green (only) wire on the receiver dryer pressure switch connector, if the wiring harness is long enough. If you can hear your compressor clutch engaging, this is also a good sign that the fuse and power relay are working.

Fuseholders and relay sockets are known to melt on these cars.

 

Hi, some news :
The 30amp hidden fuse was burn. I replace it and now the interior fan seem to be ok.
About the cooler radiator fan (left side) it is ON just after ignition ON (so engine is not hot) when the HVAC "stop" button is activated (so when AC is turn off). I can turn ON/OFF the radiator Fan just by playing with "stop" button, Is it normal?

 

Edit : there is something common between hvac and radiator fan but i don't know why the radiator fan turn ON / OFF when i play with "stop" button OR the power of internal blower...
Also the hidden 30amp fuse is very very HOT

 

Edit : i just disconnect receiver dryer switch, and now the LH cooler radiator fan is shut down
I don't know why few day ago when i try this the fan was still ON... strange
What do you think?