using a relay to switch ground?

[usar17]

Im currently installing a Mark8 fan, volvo relay, and bmw temp sensor comboin my truck. Everything im reading has people buying high amp relays to splice in to the Relay -> Speed 2 line for A/C override. My thoughts tho are, the temp switch signals the Volvo relay using ground when temperatures are reache.....can a normal relay be sliced into the temp high->relay line to override the sensor? Meaning when the ac clutch engages, that positive feed trips the relay to ground out the wire used for signalling high temp.

Im thinking A/C signal to 85, Ground 86 and 30, splice 87 in with temp sensor and volvo relay high temp position. That work? Lol

 

[highdesertrange]

well I know that a relay can switch ground just like it can switch hot. I would have to look at a relay to get the numbers straight. I am curious when you say a Volvo relay do you mean a standard bosch relay? or some Swedish wet dream. highdesertranger

 

[usar17]

If you look up Mark 8 fan conversions they talk about using a fan relay from a volvo mid 1990s. They are high amp relays that work great for this setup. Power in, fan low, fan high, ground form temp 1, ground form temp 2.

-Shawn
1985 Chevy k10 w/ 92 TBI, 94 4l60e, 91 NP208