Chevelles.com banner

1 - 6 of 6 Posts

·
Registered
Joined
·
451 Posts
Discussion Starter #1
I just installed the Windstar fans into my 69 Chevelle. I used the Painless wiring and they have the one wire goto a spot the is hot only when the ignition it on. So when I turn the car off the fan do to if they are running. Does any one have there's hot all the time so the fans can finish there cooling or is it too much on the battery or just not nessesary.
 

·
Premium Member
Joined
·
5,063 Posts
It will take forever for the fan to cool the motor with no water circulation.

You could install a timer for the fan to stay on, tricky.

I use a 3 position switch. up = temp sensor.
middle = off
lower = ON
 

·
Registered
Joined
·
131 Posts
I added that feature when I wired my Camaro a few years ago. Of course, without the water pump to circulate water, it really was pointless. I never used it other than to occasionally make sure it worked. While it never happened, it could also be a good way to end up with a dead battery.

Fast forward to the past two weeks as I'm wiring the fans in my 70. What I really missed when I was driving my camaro, was a way to turn the fans OFF when the car was riding between the thermostat and I was on the highway. In other words, my fans come on at 190, and go back off at 180. If I'm driving down the highway with lots of air flow, and the car is running 185, if the fans had come on for some reason, they would never turn off. So this time, I wired a switch to interrupt the ground signal from the temp sensor in the head, so I can turn the fans off, even if the sensor is calling for fan. I also wired in a manual switch, but it requires the ignition switched 12 v.

NOW that said, if you go that way, make SURE if you use this switch you understand that you have to MANUALLY turn it back off to get cooling fans! When you get off the freeway, you better remember to turn them back on, otherwise, you're not going to be in a good mood when you get home!!! This approach may not be good for everyone.
 

·
Premium Member
Joined
·
19,928 Posts
I had a rental car one time that the fans would stay on until the temp dropped below a certain point. While the water may not be circulating, it's actually getting hotter with the engine turned off but you can still cool the water in the radiator and it'll help cool the water in the engine as well since it's still passing heat via the lower radiator connection. Just because it's not circulating doesn't mean you can't cool the water in the block.

Whether your fan (or fans) would run down the battery until a certain temp is reached, only a few tests would determine.
 

·
Registered
Joined
·
859 Posts
Boy,.......how many times have we walked past a car in a parking lot and here the fan running? This design feature was in alot of cars with aluminum blocks which is a lot in today's OEM world. The thought process is that there will be some flow in the system due to convection and cool water will evenually work it's way ever so little to the block to help with heat soak. This was to cure or help hot start problems in hot weather and offset the building heat which would rise in the system to displace water in the lower block. In the future I think we will see OEM cars with electric water pumps that will have a "sleep" mode that will do the very same thing (slowly circulate water for a period after shut off) to reduce start up emissions when hot. It's coming just wait and see. While this works, it is not necessary for our engines.

I am not a fan (pun intended) of leaving the fan operate when the car(ignition) is shut off. Already one poster has pointed out that a battery could be weak and you come back to a nice cool radiator only to find out the battery's dead and it's simply not necessary in a properly designed cooling system for our applications.

Another issue is at work too here. When you hook your fan to an ignition source the instant you turn the key and have either the air on or the temperature is such that the demand for fan is there, the fan will come on immediately adding to the call for current along with your starter which could impede proper cranking. You don't want that either. Some ig switches have accessory positions that only provide switched power during ignition "on" periods but not when in the cranking position. So, do not hook (signal circuits for the relays) your fans up to a pure ignition or battery source either. Either work a delay with a "time delay relay" or use the accessory source if swiched.

One of the posters remarked how he was going down the road at cruise with the fans on. This is a common and overlooked design issue of the fan temperature circuit that can be remedied easily. If you have a themostat that regulates your engine temperature at 180 let's say, then you want the fans to be OFF when it's there at that point...especially when cruising and the fans do absolutly nothing except wear themselves out and take watts to do it. To design around this make sure the "turnon" temperature is above the thermostat's cycling point and the "turnoff" is as well. This means if the thermal switch will turn on at 195 and turn off at 185 the fans will be off most of the time going down the road. Now all this applies if you are sensing temperature INSIDE the temperature regulation areas. This means any head, intake or any sensing device located in front of the thermstat because the thermostat is going to be the regulating entity and control the cooling jacket if it does it's job.

The other way is to get an adjustable sensor that has the "inert" sensor which go into the fins of the radiator just below the intake. You can then adjust the unit for the optimum turn on and off points. Also, there are fixed (180 -170) "inert" units that also can be placed in the radiator at a location so that when the radiator is getting enough air at that location to cool, it will cycle properly regardless of what your thermostat is doing. This device and design assumes that even if you have a 180 degree thermostat if placed a couple inched below the entrance to the radiator, a 180 degree turn off device will see cooler water than the regulated 180 degree stuff and turn off. I employ this method alot.

Sorry for the long post. Carry on. Kinda boring Sunday morning. :D
 

·
Registered
Joined
·
451 Posts
Discussion Starter #6
Thanks for the help everyone, I am going to leave it as is with the wire to the power when the key is on only.
 
1 - 6 of 6 Posts
Top