VZ thermo fan issues

[azazeldeath]

I found out why my car was running hot one night when I was doped up on my painkillers (for my back). Turns out the fans will not kick in at all no matter how hot it gets but the second I turn my aircon on both kick in.

Is there some relay or sensor I can replace to fix it? Or some way to make them turn on when the car does regardless of the temperature?

I tried a search too many VZ overheating problems that involve the thermostat or unbled systems to find anything on this topic.

Thanks.

 

[leethal1]

the thermo fans on the car are controlled by the ecu, there are no seperate tempreature and ac relays, only high and low relays which are controlled by ecu. the ac pressure sender tells the ecu to turn fans on and the tempreature sensor should do the same. i would recommend a checking or replacing your coolant temp sensor - there normally is a gauge one and a seperate one for the ecu. does the car run ok? is it chewing through a little too much fuel? these could be indicators of a faulty sensor.


if you know someone with a cheap obd2 tool you can check your ecu coolant temp quite easily.

 

[azazeldeath]

I have an OBD2 scanner, it goes through a fair bit of fuel but it has been doing that since the exhaust, extractors, CAI, and a few other mods. The car runs fine, starts first go. Idles very smooth with about 25RPM variation at most.

Where is the sensor located?

 

[impulsive]

there is a relay in the engine bay isnt there?

 

[azazeldeath]

not that I can see

 

[leethal1]

if the fans come on with the a/c it's not a issue with the relay's issue, however if you want to check swap the low fan (smaller engine fan relay) with another one in the box near the battery (there are 2 fan relays, High and low speed)
there are only 2 options are really left - ecu U/S or the coolant temp sensor has issues, maybe even just unplugged when mods were made, do you have one of thise bluetooth obd2 scanners? torque is a good program, I think it reads the engine coolant temp from the ecu and not the temp gauge, is there any fault codes logged? the coolant temp sensor is located under the intake runners on the passenger side see link - http://drivemycar.com.au/pdfs/VZCommodoreDCL.pdf

The higher fuel consumptoin seems to say the car is running on a cold coolant temp setting ie - like a choke on an older car

 

[azazeldeath]

I have one of the handheld OBD2 scanners, no error codes at all. It only started doing it after I paid a very dodgey mechanic to replace my coil packs (while getting a rebuild). Blew up one radiator already.

I will see if its unplugged later tonight and let you know how it goes. Thank you very much for your expertise though.

 

[06Calais]

I am having same issue. I have had the Issue for along time. Its not really been a problem since I live along way out in the country, therefore temp never goes above 96, and usually around 93. However this week I must travel to Melbourne and if stuck at lights for more than a few minutes I will have problems. I also have to on Western ring Road, and 9 times out of 10 end up in a very long drawn out Traffic Jam, even now the road works have finished (God I hate that frigggin road) I still usually get jammed near the Tulla Exits, then often get Jammed near Mt alexader Road on the Tulla when on my way to using the bolty bridge, oh yeh and often get jammed on top of that too, just before the Motague Exit @ Sth Melbz. I unforetunately have to atend a specialist Doctor there once every two months. There have been very few trips in the last few years to melbs that have not had traffic Jams.

So Hopefully I can get this issue resolved.

I have OBDii Tool and Temp is showing on there.

I have replaced both Fan Relays and Fuses too.

I supose I will have to replace Sensor next, but before I do, any other ideas on what I can do. Other than replace ECU?

 

[LevelLizard]

Hi guys,

Sorry about resurrecting an old thread, but I have same Problems(thermo fan wont turn on) except only large fan working when I turn on the A/C, I checked the following:

Coolant temperature sensor shows live data through OBD2 reader
Fuses
Relay works (if I connect them manually fans turn ON so there's power.)


So looks like it is the ECU,

@6Calasis and azazeldeath What did you guys do?

I am thinking of wiring the ignition switch to the existing relays and manually operating them through a switch by myself, - bad idea? (I know cooling fans arn't supposed to be ON all the time hence.)

Thanks in Advance,
Lizard

 

[HRtoV?]

Just in case this helps anyone.

We have a similar problem in an LS1 VY. It seems the motors and control circuits have changed model to model. Ours has 3 writes going to each motor. The plug to the whole assembly has 5 wires. One of these (yellow /orange) is common and is spliced and goes to both motors.

Long story short. The motors are both 4 brush types. One set of brushes is powered for low speed and the second set also powered for high speed. Hence 3 wires. This applies to both motors.

The problem was brushes in both motors. All 4 brushes were worn to the point of not making contact in the large fan motor and only one set had any life (not much) in the small motor. You can check with a meter and should get close to zero ohms from common to any other terminal. We had Megohms where the brushes were bad.

Happy fault finding...