[62131]

Does anybody here run their fan after they shut the engine down to aid in cooling? If so would you share the circuitry with me. I purchased a temperature switch with a temperature probe to go into my radiator and it is adjustable from 160-180. What I would like to do is when I shut my engine off run my fan for a short period of time.  What I had in mind was use the contacts in the temp. switch as a latching circuit thru a relay to run the fan and when the temperature dropped below 160 degrees the relay would drop out and shut the fan off. I know I can do this by hitting a momentary switch to latch the relay but I would like it not to be a manual type circuit. Anybody have any other ideals? 

[EDNY]

In my 33 Master I have a TPI engine with (2) speed Taurus fan. I programmed the ECM to turn on the low speed range at 180 degrees.  I then wired in another relay for the "high speed range" and wired it so it can be activated with key on or no key in the ignition (hot all time).

So far the low speed range and ECM keeps the car very cool.

Don't know if you have a 1 or 2 speed fan...but if you already have a relay...you should be able to tap into it and by-pass the radiator sender with a toggle.

You can see in my picture I have the red toggle to run the high speed range.

Ed

[EDNY]

OK..after re-reading your post...I now understand where you are going.  I would think that the OEM instructions would be to wire the fan relay through the ignition. (power when key on only). Could you simply wire the relay so it's hot all the time?  Then when you shut down and remove the key...the fan will stay on until cooled?

[62131]

I have a single speed fan and my engine temperature is fine. I just want to run the fan to cool the engine compartment down. I know I can do it with a switch on the dash I would like for it to turn by it's self when I shut the engine off.

[62131]

I think what you are saying is when I start the car this will latch the relay and when I turn it off the relay will be latched and when it cools down to 160 degrees the relay will drop out.  Won't this keep the fan running continuously while  the ignition is on ?

[themoose]

I would use an adjustable time delay relay to control the fan relay circuit. It would be very easy to install and wire and you can control the amount of time you want the fan to stay on. Take a look at this example
http://www.amazon.com/Amico-Minutes-Plastic-Housing-Delay/dp/B00ARBUN1I/?tag=lowlefbacpais-20

Moose

[62131]

Moose  I thought about using a time delay relay but on really hot days I was afraid it would time out before it was cool.

[themoose]

I have read a couple of articles on the subject of how much cooling is actually done by keeping the fan running after the engine is off.
It would seem that it's minimal at best. Remember that the water pump is no longer turning so the only you will get is by the siphon effect caused by temperature differential between the radiator and the block. That coupled with the fact that the thermostat will slowly close and trap the water in the block would seem to imply that keeping the fan running for 5 or 6 minutes would probably give you as much cooling as your gonna get. You would only continue to cool the radiator and not the engine.Of course you could always install an electric water pump

Moose

[62131]

I understand what you are saying I'm just trying to remove heat from under the hood. I have another little problem that occurs at random. I always check my car out during winter getting it ready for spring. I put it on a lift give it a good going over looking for any signs of a problem.  This year  I did what I have done in the past nothing found, took it to several rod runs this spring then took it to the Nationals in L-ville car done great. Getting ready to go to the Frog Follies in Evansville Indiana, the morning of I back my car out of the garage got out to go back into the garage turn the lights out and there's a puddle of gas on the floor, I looked under the car and there is a small spot on the drive, I pulled it back in jacked it up checked all my connections no signs of a leak. Drove roughly 400 miles that weekend not a sign of a leak. This past weekend I went to the Shades of the Past got ready to leave and that morning a spot on the floor checked all connection everything tight found a small amount of gas on the fuel pump. I'm puzzled where the gas is coming from any ideals?

[EDNY]

Back to the fan, the radiator probe should have ON and OFF temperature ranges. (You can always buy a block unit with On/OFF temps).

If the radiator fan is cycling properly now...you only need to keep it powered when the key is off. It should then cycle off when the lower temp is met.

Attached a PDF of a block sending unit wiring...to give you some ideas.

Ed.

[62131]

After listening to the different suggestion I believe I will try to do it with the ignition switch to latch the relay and use my temperature controller to unlatch the relay. I think I can run it in parallel with my fan run relay which is controlled by my temperature switch and my ac compressor to operate the fan now.

[EDNY]

Here is an adjustable timer with relay, max time is 90 seconds? Has wiring diagram...they are on eBay also:

http://www.remotestartexperts.com/dei-528t.html

You could even use a tiny button type momentary switch to activate it for 90 seconds at a time? So it would only run when you want. 

[EDNY]

Talking about relays and remotes...just put this video up to show the potential for inexpensive wireless remotes.....


http://www.youtube.com/watch?v=ttgJ4R1Uv0c&feature=youtu.be