Switch help needed

Hi my og switch for my rear heated screen is playing up so I thought I would fit a replacement before its needed in the chilly months to come.
I couldn't find a VW one so I've bought a durite one until I find a replacement.
I've put it on and it works but do I need a relay or will there already be one in place somewhere that I can't see?
Cheers

 

The old switch wouldn't have a relay inside it so the new one shouldn't require one.

If it worked before (prior to the switch failing) then you should be good to go.

Having said this, its a large current draw so there should be a relay in the system somewhere - listen for a click when you operate the switch...

 

Cheers mate, sorry for being dim I guess the clicking sound is the relay?

 

Yes. I don't know where the relay is, but I'd guess somewhere near the window to cut down on the length of the high current wiring? My westy had a non-functional heated rear screen and I never did come across the relay. I should have looked harder but as the rear window didn't steam up anyway...

 

my heated screen don't work either and i cba to sort it as i don't look out the back much lol

 

I'm pretty sure that relays wen't used for the rear screens as the switch contacts were suitably rated for the current draw.

what year is your bus and I'll check the wiring diagrams

if you fit an aftermarket switch just make sure it can handle the current and you wont need a relay, if the switch is under rated for the current then fit a relay to prolong the life of the switch

 

VW didn't use a relay, although you'd think they would have. Nowt stopping you putting one in down the back, tho'

Vehicle Wiring Products sell nice chunky German rotary switches that look OK.

 

Cheers fellas not sure what the rating is for the switch or how many amps the screen kicks out, bought it from VWP it's much smaller than the VW original. I did buy 2x 40 amp relays at the same time just in case and I wanted one for a heated front screen which I hope to get before the winter arrives.
I noticed the rotary ones snotty, wish I'd bought one of those now I can see how tiny the pull switch is.

Rick and Zed if you use your bus as a daily through the winter with next to no heat, as I do. I can almost guarantee you will get a misted rear screen

Diddly it's a 79 cheers

Cheers for your help.

 

I was told the heated front screen has 2 elements one for each side so it may be prudent to use both those relays when you fit it and link them together for 1 switch operation.

you'll also need to make some holes in your dash top for the cables to drop through - its something Im going to fit to mine

 

79's didnt use a relay either for rear heated screen, just a suitably rated switch

here's the diagram:-

http://www.vintagebus.com/wiring/bus-79c-1.jpg

fed from a 16A fuse so current draw would be between 10A and just under 16A I would imagine (other wise the fuse would constantly blow)

 

Just checked and acording to the Bently manual, switch current for 1975 & later busses is 10A so if that is correct then your 12.5A switch should be fine ...........but I've never checked the current draw on a bus rear window so can't confirm that.

........and according to Bentley :-

'A relay in the engine compartment controls the temperature of the heated rear window'

although this doesnt seem to be shown on any of the wiring diagrams :headscratch2:

A time delay relay would certainly be a good idea to cut it off after a certain time to protect the heating element from burning out though like they have on modern cars.