Monday, November 27, 2006 - 08:08 am, by: Rehan Bandara(Parsec)
Does anyone know what causes the small electric fan behind the radiator and the bigger electric fan in front of the radiator to click on?
I just installed my FMIC and noticed that the car overheats a little when belting it on the freeway. (the temperature gauge raised one notch from the centre)
I left it idling when i got home and noticed that the electric fans weren't clicking on, despite the car being pretty damn hot at the time.
What's the most likely thing to fail here? The fans, a relay, or a fuse?
Has anyone wired the fans straight up to their ignition circuit so they are running constantly when the car is on?
I'm thinking i may need to shove that shroud back into the car above the FMIC to get some air flowing back onto the radiator...
Monday, November 27, 2006 - 09:58 am, by: Mark Paddick(Sparks)
Aircon. You could use a relay to turn them on via a temp switch circuit from the engine temp sender.
The factory shrouding and ducting is there for a reason. I'm sure they'd save the money if it wasn't needed. Replacing the factory clutch-fan with a hydraulic one from a V8 or similar is a better idea than using the electric fans. The electric fans are needed for when the aircon is working so using them will still leave you short of fan power when it is on. Or just fix the ducting with the factory fan setup and maybe a colder thermostst.
Monday, November 27, 2006 - 10:13 am, by: Tim Appleton(Timbo)
I don't think that the fans will have much effect when you are belting along the freeway. They are usually there for when you are sitting at idle. Think about sticking your hand out the window when driving at highway speeds, and equate that to how much air the little fans on the radiator have to push to achieve that sort of force.
Can I suggest you check your thermostat, but it does sound like your fans should be kicking in when stopped. Sorry, I can't provide any help on this.
Monday, November 27, 2006 - 10:28 am, by: Rehan Bandara(Parsec)
I tried turning the air con on to see if i could get the fans running, but it didn't help. So are both fans for the aircon?
Maybe i need to run the airocon for a while for them to click on.
Yeah, i'm pretty much resigned to putting the ducting back on as the fans are relatively weak.
I would like something more powerful for idle though. I figure running too much cooling all the time (whilst driving) is bad as the engine produces less power if it is overcooled (as additional heat which could be driving the pistons is lost to the coolant).
Where are the thermostats located? I noticed one on the front bar, which looks like it's there to determine the ambient air temp.
Monday, November 27, 2006 - 01:18 pm, by: Mark Paddick(Sparks)
If the thermostat is working then you can't overcool an engine, or it's got the wrong thermostat. Changing to a colder one is a good idea as you will be making more heat with the extra power and most engines are run hotter than would be otherwise the case to meet emissions laws which we will assume you don't care about.
Both fans are controlled by an engine temperature and airconditioning head pressure switches. In series and with a relay. Both temp and pressure have to be high for the fans to come on. Aircon has to be on for head pressure to be high enough and engine has to be up to operating temp.
Electric fans can only be switched on or off. The hydraulic fan is controlled by a solenoid and computer. It is continuously and instantly variable in speed from off to flat-out.
Monday, November 27, 2006 - 04:34 pm, by: Daniel Clarke(Dieseltrain)
Engine temps rise while under wide open throttle? I would get your radiator checked. It may be in need of a recore. Blocked cores will increase coolant temps as an engine is working hard.
Engine fans do very little in the way of pulling air through the radiator at Speed. They are only to help the engine draw through air( or the electric ones switch on and draw air) when the vehicle is at low speeds.
Ben Socratous Goo Roo SA I am the fibreglass/kevlar/carbonfibre king!
Monday, November 27, 2006 - 05:10 pm, by: Ben Socratous(Socrates)
Mark Paddick wrote on Monday, November 27, 2006 - 01:18 pm:
Both fans are controlled by an engine temperature and airconditioning head pressure switches
I have no aircon atm (dead compressor) and the front electric fan still works, that is what I tapped my thermo fans into. My aircon hasn't been used in nearly 2 years and that fan still cuts in and out when needed, tripping the new thermos while it is at it.
Monday, November 27, 2006 - 05:17 pm, by: Rehan Bandara(Parsec)
I had my radiator reconditioned fairly recently. I was under the impression they replaced the core, but i may be wrong. The top tank is certainly different. The core was leaking as well... so i'm not sure whether they can seal that or whether they need to source another one.
I just put some radiator flush through and started using a decent coolant last week. Does anyone know if anything else is involved in unblocking a radiator?
I'll have to check the relay then, as my car was well up to operating temperature.
Monday, November 27, 2006 - 05:48 pm, by: Mark Paddick(Sparks)
Quite a lot of rewiring gets done around there (front impact, panelbeaters and wiring don't mix) so I wouldn't be surprised what you'll find.
It seems that it is a separate temp sender switch for the engine temp. I would change it for a thermistor type like the temp gauge and use a Jaycar temp switch kit or similar to drive the fan(s). Or just use the temp guage sender and the kit (it won't interfere with the temp guage reading). The aircon pressure sensor can then be used as a 2nd input for the relay driver of the kit so the A/C pressure will still turn the fan on irrespective of temperature of the engine (or it could just be wired across the relay or wired to switch it). The engine is not likely to be stone cold if the A/C is on flat out and built up enough pressure to trip the switch.