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Location:
Ipswich
Registered:
October 2003
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Thermofan switching and hysteresis
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Sat, 11 June 2005 08:44
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I've just finished building and calibrating a jaycar adjustable temp switch to run the thermofans via a relay for my 1ggte. I've managed to get the switching temps to on at 92 and off at 81. The pots are a bit too sensitive for me to get much better than that, so i'm wondering if these will be fine?
Anyone used these kits for this purpose before? Are they reliable enough to relay upon for this application. I'm also going to have a swtich wired into the cabin as a safety to bypass the temp switch and manually switch the fans on, if there is a problem.
Cheers, Matt
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Location:
Brisbane
Registered:
May 2002
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Re: Thermofan switching and hysteresis
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Sat, 11 June 2005 08:55
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The off seems a bit low?
If your thermostat is an 82deg, your thermos will be on all the time? I thought the idea was to set the off a few deg above ur thermostat opening temp?
Cheers
Wilbo
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Location:
Brisbane
Registered:
February 2003
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Re: Thermofan switching and hysteresis
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Sat, 11 June 2005 09:18
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is the jaycar kit designed for under-bonnet use?
i have a homebuilt kit controlling my aircon ( but that all lives behind the radio) and the the circuity in it is affected by ambeint tempretures.
an alternative would be the thermo fans switch out of a FWD EFI corolla (switched to ground when trigger point set, passive nature of sensor deals with hysteresis issues)
another alternateive would be lower tolerance pots?
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Location:
Canberra
Registered:
May 2002
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Re: Thermofan switching and hysteresis
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Sun, 12 June 2005 06:45
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Wilbo, The water leaving the radiator, "MUST BE COOLER THAN THE WATER IN THE ENGINE".
So an engine with an 82 deg C thermo, must have a cooling system capable of pulling the temp down below 82 Deg.
cheers Chuck.
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Location:
Ipswich
Registered:
October 2003
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Re: Thermofan switching and hysteresis
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Tue, 14 June 2005 22:24
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Cheers charles, I may just go for a proper temp switch as you suggested, i'll find someone with a tridon catalogue today. So some toyota switches are normally closed, some normally open? The corolla one sounds the go, thread issues won't be a problem, i'll just be getting a shop to braze and tap a fitting into the remote filler pipe thing.
Ah well, I can always use the box to operate something not so critical, intercooler spray, or something.
Cheers, Matt
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Location:
Brisbane
Registered:
May 2002
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Re: Thermofan switching and hysteresis
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Wed, 15 June 2005 01:22
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| ChuckLandwehr wrote on Sun, 12 June 2005 16:45 |
Wilbo, The water leaving the radiator, "MUST BE COOLER THAN THE WATER IN THE ENGINE".
So an engine with an 82 deg C thermo, must have a cooling system capable of pulling the temp down below 82 Deg.
cheers Chuck.
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One would hazard a guess that it would depended if the sensor was located in the top tank of the bottom tank of the radiator.
I was assuming it was mounted in the top tank. 
The corolla switches are 85->90-something or something like that??
Cheers
Wilbo
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Location:
Brisbane
Registered:
February 2003
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Re: Thermofan switching and hysteresis
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Wed, 15 June 2005 09:32
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look for FWD EFI corolla thermo fan switch on thermostat housing on engine.
only car that i've seen temp sensor in the radiator was a Cordia - and it was in bottom tank. Was stupid wiring setup - sensor was normally OC when cold, so if the wire got knocked off the sensor or it failed OC, the fans would never come on the motor would overheat. great design... not.
matt: i'd also suggest sticking a sensor in one of the ports on thermostat housing, or in the piping from housing to radiator. you might not get enough water flow at a remote filler to accurately reflect post-thermostat water temps?
what's the part # of the jarcar kit?
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Location:
Ipswich
Registered:
October 2003
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Re: Thermofan switching and hysteresis
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Wed, 15 June 2005 13:13
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Charles, the part number is KC5381.
The remote filler I have is actually a piece of steel pipe with a filler cap, clamped between two parts of radiator hose from the thermostat outlet to the top inlet of the radiator. Thats what I was going to have tapped on the underside. I may have the terminology wrong, calling it a remote filler?
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Location:
Brisbane
Registered:
February 2003
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Re: Thermofan switching and hysteresis
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Thu, 16 June 2005 01:45
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matt: your terminology is correct - perhaps 'inline filler' might be more grammatically appropriate. - but it would be the best place for it 
when i scored my 1G it had a small tank bolted on guard and connected to the end-tank and block with flexible hose. it would have made bleeding the cooling system a minor pain.
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