Jump to content

Cooling Fan Thermo Switch


Recommended Posts

hi guys n gals.

i've fitted an electric cooling fan.

i also made a pipe/housing to thread in a fan switch in the top hose.

i used a 95-90 degree c switch, but lettin the car tick over the gauge goes upto the red and fan does'nt come on?

i darnt leave it any longer so i bridge the wires out to run the fan..just wonderin if anyones using a similar rig, if so what temp switch heat range you using?

just to add the fan and wiring are all correct and workin and the system is not airlocked , however the fan switch is new but its a INTERMOTOR one so could be dicky?

anybody kno what temp is when gauge near the red? on a manta b ...ta

Edited by mantapaperman
Link to comment
Share on other sites

I've got a similar setup and use a 100/95 degree switch (fairly sure it's an intermotor too), needle hardly gets above the middle before the fan cuts in which seems a bit early for that temp range so I'm assuming my gauge or gauge sender isn't reading right.

Just a thought - where's the sender located in the pipe?

Needs to be underneath so it's always in the water flow.


Edited by Christ
Link to comment
Share on other sites

Its possible your new thermo switch is faulty, a leasson i learnt years ago was just because its new doesn't mean it is working :unsure:

Stick a couple of wires on it to a multi-meter set to continuity and put it in a pan of water on the stove and bring to the boil.

That should tell you if the switch works.

However my guess to your issue is that you are suffering from the common Manta problem of a broken voltage regulator

Its mounted on the rear of the dash and is there to give a constant 10v to the fuel level gauge and temp gauge, when it blows they get the around 13.5 Volts and read high

So you get the temp gauge into the red when the engine isn't actually that hot.

I fitted a thermo switch into a 24v conversion recently and when first run up it went into the red within 5 minutes.

A quick squeeze of the water pipes told me it wasn't actually that hot as the pipes weren't solid from pressure in the system and we had no leaks.

So i swapped the old voltage regulator for a modern version and suddenly we were back down to under 1/4 on the gauge.

10 mins later the temp was up towards 3/4 and the fans kicked in.

Also the thermo switch should be in the bottom radiator pipe not the top.

The fan is only needed when the water returning from the radiator to the engine is too hot (ie the radiator can't cool the water enough) the fans then help cool the water in the rad.

If you have it in the top hose it will only sense the temp of water leaving the engine and run too much/often

Link to comment
Share on other sites

thanks for the replys guys...

christ my setup is same as yours,but plastic.and the sensor attachment is about an inch from the pipe itself so maybe the water isnt flowing in and out enough? not getting hot as quick as the passing water so to speak..

i was goin to weld a M22x1.5 nut on a steel tube like yours but couldnt find that size nut, were did you get yurs? anyway i think the gauge is correct cos it is getting rather hot when the gauge gets near the red..i think a metal tube/nut rig is the way to go

then the end of the sensor will be nearer the water flow..thanks guys

Link to comment
Share on other sites

Sounds like you might have found the problem.

I used an M14x1.5 nut and spent an age going through the sensor catalogue at the local parts shop trying to find one with the right temp range and m14 thread (think it's for a rover??)

Link to comment
Share on other sites

just an update..got a new switch and housing, but still no fans coming on. i've put a thermometer in top of rad and its 95 deg c when gauge near the red. should i be giving the fan switch a live feed?

i'm currently earthing the the switch and feeding the fan? so the rad switch should switch the earth. do these bi metalic thingys need a live? cheers guys

Link to comment
Share on other sites

I always switch the earth and have never had a problem doing it.

Have you tried the switch connected to a multimeter in a pan of water on the cooker to test it?

Put a thermometer in there and see if it does switch and at what temp, its possible the label of 95-90 isn't 100% accurate to the temp it will switch at.

Link to comment
Share on other sites

right guys thanks for the help..just to say; i have used a relay, switching the earth thru the rad switch. if i connect the two rad switch wires together the fan runs great.

removed switch and put in pan on hob and it works around 97 deg c. when i run car its hitting the red and if i put my thermometer in rad top it reads 95-97. i just dearnt run it any longer?

do you think i should get a cooler rad switch,say 85 ish? cheers again guys..i will try it in bottom hose tonight..

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...