Since fitting a new radiator I have a twin fan shroud on my Mk2 Golf. It’s running the standard rad fan only and I’d like to utilise the space in the shroud for a second fan. I have a slimline fan bolted up which fits nicely but rather than wire it in to the standard setup I was thinking I’d like it to be a standalone and have a switch on the dash using a spare Mk2 switch I have. I’ll be the first to admit my electrical knowledge is very basic so would appreciate some help in confirming if my diagram below is correct using a 30 amp relay? Thanks!
dont bother just wire the 2nd fan up to the first one, jobs a goodun. if you really must have a switch you can tap it into the red/white wire so the original switch will still run both and the switch can be used for emergency back up, some fan looms have an extra spade plug inline which is used for rad fan after-run relay. if you got that then plug it in here, if not add a spade so fan loom and dash switch loom can disconnect. can use a relay if your dash switch isnt rated high enough to run the fan direct, live or earth switched whatever you prefer pop an inline fuse on switch feed if live switched. diagram is correct except most relays are 4 terminal so you'll need to run a live to the switched side as well as the trigger earth from your switch: 30 - live in 85 - earth trigger, run to switch 86 - live trigger, loop to 30 in this application 87 - live out
Thanks for info RJ and confirming my dodgy diagram! So if I wired the slimline fan direct all I need to do is tap into the low speed wire on the rad fan switch for live and then earth the other fan wire? I was planning on using a spare MK2 dash switch I have (think it's a rear window demister one) if I went the switched route. Just figured a relay would be a good idea for safety. Pretty sure that extra plug is there from memory.
yeah just tap into the same pins as the current fan, best to check the load of both together doesnt exceed the stock 30a fuse though. aftermarket fans usually pretty low ampage so usually no problems demister switch can take a decent load so should be alight direct again dependign on combined load from both fans, but may as well add a relay if you're adding wiring anyway