Help needed with a Thermo fan

RX MIDGET · 02-02-2011, 04:23 AM

Hi,
After connecting an Autometer Water Temp gauge, my Davis Craig fan does not come on at all!

(Note: Tested up to 110 degrees C without it coming on - however I thought that the gauge reached the 110 degrees C alot quicker than I am used to - just 4 minutes).

The fan is wired through the supplied Autometer sender in the radiator - the gauge appears to work no dramas!

I have had a good look on the fan, but can not find an adjustment switch. Why would it need adjustment - as it worked well with the crappy old gauge???

Could the problem be the last gauge was degrees F and the new one is degrees C?

Note: I am replacing the old gauge as it was "mis-matched" with the old sender - normal driving (after 10 minutes warm up) it sat on 230 degrees F with the thermo fan coming on at 240 degrees F, ever since I have owned the car.

I am lost, any suggestions? HELP!
(RX MIDGET - 13B N/A Extend Port)

C. Ludwig · 02-02-2011, 07:38 AM

I would use something like this versus the little probes that you stick in the radiator fins. Drill and tap the back of the water pump below the thermostat and you're ready to go. These types of switches are available in different temp ratings. I would definitely want the fan to come on sooner than it has been in your case.

http://www.amazon.com/Sierra-TEMPERA.../dp/B001RIJGPO

t_g_farrell · 02-02-2011, 08:58 AM

How is the fan relay wired up to operate from the temp sensor? Just the
sensor input alone won't trigger that relay I expect. There must be thermal
switch inline with the relay that needs to know the temp. Maybe when you
replaced the old setup it lost that input along the way?

RX MIDGET · 02-09-2011, 04:23 AM

Guys,
After talking to someone in the know, it was suggested the previous radiator may be running / switching the fan and have no gauge association. This was correct. There was a second sender (under the thermostat) driving the gauge. I put the newly purchased Autometer sender under the thermostat and returned the old sender to the radiator. The single line to the fan was power, not gauge. Presto, problem solved, so thanks guys...

***TitaniumTT*** · 02-09-2011, 01:39 PM

The sensor under the thermostat is for the ECU. Is this an EFI car or a carbed car? EFI cars use that location for the ECU and the gauge pulls temp from a sender in the rear iron. Removing that sender from the ECU will result in a very poorly running engine.

Like Ludwig said, under the T-stat is the best place for it, but if you can't get there, there is a recess in the t-stat housing that I've used in the past. The problem is you won't get a trully accurate reading until the t-stat opens.

02-02-2011, 04:23 AM	#1
RX MIDGET MG rocket Join Date: Oct 2010 Location: Victoria Australia Posts: 40 Rep Power: 0	Help needed with a Thermo fan Hi, After connecting an Autometer Water Temp gauge, my Davis Craig fan does not come on at all! (Note: Tested up to 110 degrees C without it coming on - however I thought that the gauge reached the 110 degrees C alot quicker than I am used to - just 4 minutes). The fan is wired through the supplied Autometer sender in the radiator - the gauge appears to work no dramas! I have had a good look on the fan, but can not find an adjustment switch. Why would it need adjustment - as it worked well with the crappy old gauge??? Could the problem be the last gauge was degrees F and the new one is degrees C? Note: I am replacing the old gauge as it was "mis-matched" with the old sender - normal driving (after 10 minutes warm up) it sat on 230 degrees F with the thermo fan coming on at 240 degrees F, ever since I have owned the car. I am lost, any suggestions? HELP! (RX MIDGET - 13B N/A Extend Port)

02-02-2011, 07:38 AM	#2
C. Ludwig Rotary Masochist Join Date: May 2008 Location: Floyds Knobs, IN Posts: 494 Rep Power: 18	I would use something like this versus the little probes that you stick in the radiator fins. Drill and tap the back of the water pump below the thermostat and you're ready to go. These types of switches are available in different temp ratings. I would definitely want the fan to come on sooner than it has been in your case. http://www.amazon.com/Sierra-TEMPERA.../dp/B001RIJGPO __________________ _______________________________________________ *One stop Haltech, AEM, Syvecs shopping. Installation and tuning.* http://www.lms-efi.com *Free support. Drop us an email.* chris@lms-efi.com 502-515-7482 Facebook @LMS-EFI

02-02-2011, 08:58 AM	#3
t_g_farrell Waffles - hmmm good Join Date: Aug 2008 Location: Huntersville, NC Posts: 757 Rep Power: 0	How is the fan relay wired up to operate from the temp sensor? Just the sensor input alone won't trigger that relay I expect. There must be thermal switch inline with the relay that needs to know the temp. Maybe when you replaced the old setup it lost that input along the way? __________________ 1980 GS stockport, Fat Nikki, RB Dual Facetfuel pumps, Holley regulator, RB Street port exhaust, 2GDFIS, MR2 MK I electric fans, 2G strut bar, relayed fans, lights and fuel pump, LEDs Project Fat Nikki Budget 12A rebuild Video setup < $30.00

02-09-2011, 01:39 PM	#5
*TitaniumTT* Test Whore - Admin Join Date: Mar 2008 Location: Right Behind you son Posts: 4,581 Rep Power: 10	The sensor under the thermostat is for the ECU. Is this an EFI car or a carbed car? EFI cars use that location for the ECU and the gauge pulls temp from a sender in the rear iron. Removing that sender from the ECU will result in a very poorly running engine. Like Ludwig said, under the T-stat is the best place for it, but if you can't get there, there is a recess in the t-stat housing that I've used in the past. The problem is you won't get a trully accurate reading until the t-stat opens. __________________ -The Angry Stig- DGRR 2009, 2011, 2012 & 2013 - Best FC DEALS GAP!! WOOHOOOO!!!!! 2015 Audi S4 - Samantha - Zero Brap S4 2004 RX8 - Jocelyn - 196rwhp, 19mpg fuel to noise converter 2000 Jeep Cherokee Sport - Wifey mobile - Now with 2.5" OME lift and 30" BFG AT KO's! So it begins 1998 Jeep Cherokee - 5 spd, 4" lift, 33" BFG's - Rotary Tow Vehicle 1988 'Vert - In progress 1988 FC Coupe - Gretchen -The attention whore BEAST! I'm a sick individual, what's wrong with you? I'm pure Evil I'm still insane, in the best possible way. I think Brian's idea of romance is using lube. Your rage caused the meteor strike in Russia. The Antichrist would be proud of his minion. You win with your thread. Most everything It's a truck with a steel gate on the back. Just a statement of fact Motec M820, AIM dash, ported 13B-RE Cosmo, 6-spd trans, 4.3 Torsen, custom twin wg fully divided mani, Custom 4" split into 2x 3" exhaust, Custom HMIC, Custom custom custom custom I like to welder stuff.... No Bolt-ons allowed. Dyno'ed @ Speed1 Tuned by me - 405rwhp on WG.... WM50 cuming soon. *-Angry Motherfcker Mode ENGAGED-**

02-09-2011, 04:23 AM	#4
RX MIDGET MG rocket Join Date: Oct 2010 Location: Victoria Australia Posts: 40 Rep Power: 0	Guys, After talking to someone in the know, it was suggested the previous radiator may be running / switching the fan and have no gauge association. This was correct. There was a second sender (under the thermostat) driving the gauge. I put the newly purchased Autometer sender under the thermostat and returned the old sender to the radiator. The single line to the fan was power, not gauge. Presto, problem solved, so thanks guys...