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The only place for a coil spring is up Zebedee's
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Joined: Nov 16 2020
Posts: 8

Dear All,
I'm talking about the heater core temp sensor on the aluminium pipes into the heater core, not the A/C sensor on the other side.
Well it looks like there's only one left in the world, in Latvia, and he wants £100 for it. As its a thermistor that could cost just a few pence is it possible for us to put our heads together and source an alternative? I'm told by Martin Cox that it maybe a 10K ohm or 22K ohm @ 25'c NTC thermistor. Can anyone confirm this? Alternatively could anyone with a working one possibly measure its ohms and make a note of the temperature at the time, even better still measure the ohms at two different temperatures, one hot one cold? Once we know what spec thermistor it is it will be easy to rig up a mount of some sort.
i'm not keen on getting one from a breaker as its likely to be as old as my own and moving and manhandling these 25 yr old components not always good.

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Joined: Dec 30 2015
Posts: 5212

I knew the question had been dealt with before, https://rangerovers.pub/topic/1259-heater-core-temperature-sensor?page=3. Seems a 22k Ohm NTC thermistor is what you need, so one of these https://uk.rs-online.com/web/p/thermistor-ics/1912279/ would probably work fine. You'd need to insulate the wires (or wrap a bit of tape around the pipe so the wires don't short together) and attach it with a tie wrap but at 81p each with 4 spares, it's got to be better than a 3 figure price.....

Member
Joined: Nov 16 2020
Posts: 8

Thank you that man. No idea how i didn't find that. Thermistors ordered.

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Joined: Nov 16 2020
Posts: 8

cross post from RR.Net

Dear All,
Thanks for all the help. That reading is fine and is pretty much what mine reads under hot and cold water, its quite a steep linear relationship. here are some photos of how i rebuilt mine using a 22K NTC thermistor and some rapid araldite. the thermistor is buried in potting compound and sits into the hollow in teh round metal plug that faces the heater pipe, i suppose i could have just ground that out and rebuilt it as one unit but by then i'd engaged hacksaw rather than brain!

the component parts

enter image description here

soldered in

enter image description here

then sealed with Araldite

enter image description here

Member
Joined: Nov 16 2016
Posts: 1023

I always thought Araldite melted at around 100C ?

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Joined: Dec 30 2015
Posts: 5212

No, it just goes a bit rubbery. Anyway, if your heater matrix inlet got up to 100C you've got more things to worry about.

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Joined: Aug 05 2019
Posts: 158

No photos visible, at least for me.

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Joined: Dec 30 2015
Posts: 5212

They are for me. Just checked, they are Google photos, maybe they are location limited? Paul posted the same result and pictures on the dark side, maybe pictures from there will work for you https://www.rangerovers.net/threads/heater-core-temperature-sensor.57289/#post-2322902

Member
Joined: Jan 16 2016
Posts: 431

No pics for me either. I am in the UK.
update: just used my VPN. disguised my ip as germany ... no pics. Tried it as USA ... still no pics on this site only.
RR.net OK. I can see the pics.

Member
Joined: Nov 16 2020
Posts: 8

Dear All,
Whats the official way to add pictures or images on this site? I've used the image icon above and pasted the photo's web address but clearly does not work for all. Is there another way?

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Joined: Dec 30 2015
Posts: 5212

That's how you should do it although when I've tried to post from Google Drive in the past it didn't work. Most now upload the pictures to Imgur.com and copy and paste the Direct Link from there.

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Joined: Jan 16 2017
Posts: 817

Onedrive also works, just find the pic on onedrive (if you have it on the pc rather than browser right click it first and choose view online) then click the embed option and it will give you a code, copy that into the photo link and it should display then.