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Heater blower switch/wiring query


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I'm with Stuart on this. My '66 TR4A, '68 TR250 & the '69 TR6 I restored all had white coming out of the heater casing which is connected to a black wire to ground.

 

This is the heater out of the TR6.

 

post-197-0-83107300-1500253585_thumb.jpg

 

Cheers

 

Graeme

 

 

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Hi David

 

Sorry I didn't pick up on this earlier . I had the same problem as you and can confirm that the white wire is earth and connects to a black one behind the H frame and the plain green is the live feed to the switch.

 

As for the offending switch terminals one was so poor it snapped of at the base, the other spare I insulated.

 

I only got round to sorting this out a few weeks ago ,so is still fresh in my ageing brain.

 

Cheers

Brian

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Hi David

 

Sorry I didn't pick up on this earlier . I had the same problem as you and can confirm that the white wire is earth and connects to a black one behind the H frame and the plain green is the live feed to the switch.

 

As for the offending switch terminals one was so poor it snapped of at the base, the other spare I insulated.

 

I only got round to sorting this out a few weeks ago ,so is still fresh in my ageing brain.

 

Cheers

Brian

 

Brian,

 

Thanks for adding to picture - I think I'm there now. Pleased I was on the right track and everyone's contribution has helped in the confidence stakes. I guess the current bullet on the ratty dangling White was originally used to connect to the Black earth you mention. There is no evidence of a Black behind/on the H frame, but easy to resolve I think. Cant help thinking that a Black exiting the heater box 50 years ago would have been a better position - hey ho :blink:

 

I plan to insulate the spare terminals!

 

Best

 

David

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David,

I have an early TR6 PI (1970), and my earth is....

White.

It comes from the heater motor in white, together with G/Y and LG/N.

It is connected under the dash with a buttet connector to a black earth wire which has a ring-connector on the other end that connects to the metal facia.

Regards,

Waldi

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David,

I have an early TR6 PI (1970), and my earth is....

White.

It comes from the heater motor in white, together with G/Y and LG/N.

It is connected under the dash with a buttet connector to a black earth wire which has a ring-connector on the other end that connects to the metal facia.

Regards,

Waldi

H Waldi

Thanks for the information, the White is without doubt the earth, given the concrete evidence that is being presented. Amazing what a little support does for ones confidence! Your installation sounds exactly like mine should be - I just need to rig the Black earth to the H frame area.

Regards

 

Daid

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Hi David,

with the white wire earthed and the fan running the white wire voltage will be 0V.

 

And thus Stuart does it again - pure genius.

 

Roger

Roger

 

Did the test this morning - IGN On, Fan speeds 1 or 2 selected, White wire earthed, fan runs and 0v on White - great, thanks!

 

Now Im certain how the switch needs to be wired, I just need to check that the casing isnt live before I re-assemble everything (I had the problem of the fuse blowing when the switch is in situ).

 

Neil posted a link to this earlier http://www.tr-regist...ter-fan-switch/, to which you contributed - a thread I hadnt found prior to starting this one.

 

he resistance measurements between each spade terminal and the switch body (IGN ON) is 13-14 MOhms for every reading, and putting a meter between the switch casing and a good earth shows 0v. Hopefully evidence that previous shorting when switch is in situ is from one or both of the two spare spade terminals shorting out on the adjacent metal work, rather than a live casing?

 

Thanks

 

David

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Hi David,

I noticed on the Blue Racer a little earlier that indeed the white wire is there.

 

 

Why did they use white !!!!!!!!

 

Roger

Thanks! Why White??? A question Ive been asking myself of late! Has been a good learning process though :)

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Hi David,

While you have the switch out you can test it for internal resistance for both positions.

I checked all my switches, some had 3 to 5 Ohm resistance, probably enough to burn the switch.

A small amount of contact-spray to the inside of the switch resolved this.

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