2000 V70 Cooling Fan Not Working, Possible ECT Failure

s10lowrider1994 · Post by **s10lowrider1994** » 09 Mar 2015, 19:08

Trying to troubleshoot my cooling fan issue and wanted to run the diagnosis past those with more knowledge of the subject.

So here's what happened and what I've done so far. Cooling fan randomly stopped working, wont function on either speed, doesn't respond to the A/C being on or off. I pulled the middle connector off of the relay and grounded each pin, fan works on both speeds when pins are grounded. Fuses are all fine and wiring appears to be intact with no issues. With the car running, if I unplug the ECT, the fan kicks on. With the ECT plugged in, the fan is dead. I'm assuming this means I have a faulty ECT but wanted to check before ordering. Anything else I should give a look to first? Thanks!

Post by **misha** » 09 Mar 2015, 20:09

Check engine light on?
Codes?
Temperature gauge needle on instrument cluster works?
I think you have cooling fan relay problem or it's wiring.

Post by **Ozark Lee** » 09 Mar 2015, 20:18

An important part of the equation, does the A/C actually work?

Based on the test you ran by grounding the pins on the relay it appears that the relay and the fan are both operating as they should. Unplugging the ECT sensor will cause the fan to turn on and that is normal. Since the fan does trigger on with the ECT unplugged it appears that the ECU and the wiring from the ECU to the fan relay is OK.

It could very well be that the fan is indeed operating properly but the A/C isn't. The fan relay only gets triggered when the A/C system reaches operating pressure, it isn't triggered just by the A/C switch being turned on. Under normal operating conditions the fan runs very little except when the A/C is on and then it operates continuously.

...Lee

s10lowrider1994 · Post by **s10lowrider1994** » 09 Mar 2015, 20:52

No CEL, no codes, temp gauge appears to be working as it should, a/c works perfect. I have had random hard starts though which made me think it was ect related.

Post by **Juan62** » 10 Mar 2015, 11:38

Same symptoms I've had in the past six months, so I replaced my ECT, thermostat, drained and added new coolant...it works fine. My last waring given is when it did finally start, the coolant temperature gauge went from normal-hot-cold on my way to work. I turned around and shut her down till I got home to fix her. I also notice a small leak coming from the ECT.

Post by **deepsouth** » 12 Mar 2015, 17:13

I've had the misfortune of replacing many ECT's and generally my only symptoms are (occasionally) hard start, and (most common) the cooling fan won't turn off.

Post by **misha** » 12 Mar 2015, 19:44

s10lowrider1994 wrote:No CEL, no codes, temp gauge appears to be working as it should, a/c works perfect. I have had random hard starts though which made me think it was ect related.

Hard starts alone doesn't point to bad ect.Usually,when it starts to go bad,cooling fans are continuing to work after the engine is stopped along with hard stars and temperature needle playing up.
What do you mean by hard starts,more cranking time?
On these cars,usual culprit would be a fuel pressure because of a bad check valve in fuel pump.Of course...it could be numerous things.

s10lowrider1994 · Post by **s10lowrider1994** » 28 Mar 2015, 02:47

The hard starts were random and didn't happen often, the fans did run after shut down quite often though. Anyway I replaced the ect and it appears the issues went away. Fan is back to working like it should.