Relay for 2nd A/C condenser fan problem

Currently I have a radiator fan that comes on both when the temp gets above a certian point AND when the a/c compresser kicks on.  The condenser fan for A/C is now hooked up to nothing.  I want both to operate in the same manner, when either the A/C kicks on or the temps get above normal.

Here's where i got to...I have the POS/NEG wires going to the working radiator fan sitting in front of me.

So...i cut the POS radiator fan wire and hooked the POS feed to pin 86 wire the fan side connected to 85 (so the current flows through relay).

Next i hooked the A/C condenser fan POS to pin 30, with the remaining pin 87 hooked to a constant 12V.

Is this correct?  The second fan will not kick on and when the first (radiator) fan turns on the relay isn't popping the bridge across pins 30 and 87. 

I also thought that maybe the POS of the radiator fan shouldn't be cut and ran through the ralay but just simply have a branch of the 12V from the radiator fan at pin 86, in that case i hooked pin 85 to ground but everytime the first fan went on I blew a fuse.

I'm lost, i've used relay's before in similar applications but for some reason i can't get the 12V to bridge to my second fan.

PS - I've tested the 2nd fan with 12V and it runs, used my voltmeter to narrow it down to the pins 30/87 not getting continuity.

Thanks,

Vince

87 (Yellow) Power Positive (+)

Ignore the bottom lines about the temp sensor, i was just using that as a guide when writing the post.

Thanks,

Vince

This part about wiring the fan to the relay is correct.. pin 86 to Fan #1 positive (this assumes that the positive wire on Fan #1 is switched and that it's not the ground that's being switched) and Pin 85 to ground.. This should energize the relay.  What fuse are you blowing?.. check to make sure that pin 87 isn't grounded and the circuit powering pin 30 is the one popping the fuse..

Questions?..

(Sorry I didn't get back to your posting earlier.. between midnight and 7 am I was sleeping and went straight to work.. )

Jim

Your second idea was following the correct logic to activate the AC fan relay, you must have something wired up incorrectly to be blowing a fuse.

I have attached a diagram as a guide for the AC fan relay wiring.  Reconnect the positive feed back up to the radiator fan and just connect a feed from the positive fan wire to relay terminal 86 to activate the AC fan relay when the radiator fan comes on. The feed wire to terminal 86 can be a small gauge wire, like 16-18ga as the relay will only need a few hundred milliamps to activate, so I can't understand why you are blowing a fuse.  Then following the diagram, wire the AC fan positive to terminal 87 and the constant 12v feed to terminal 30, with 85 being a simple ground.

The important thing to pay attention to is the connection to the radiator fan positive wire to the relay terminal 86 has to be made somewhere along the the wire going directly to the radiator fan, after whatever wiring is controlling this fan.  Since the radiator fan was working correctly, in regards to coming on with the temp sensor and the AC compressor, you want to make sure you connect the wire to relay terminal 86 from the power feed to the radiator fan after the relay(s) that are currently controlling the radiator fan. Then the AC fan should kick in when the radiator fan comes on.

Thank you both,  I'm pretty sure i hooked it up wrong the first time and possibly blown the relay...I think the first time i ran the power wire for the rad fan through the 85-86 pins and ruined it.  Then when i corrected it the relay would totally ground out the 12v switched blowing my rad fan fuse.

Thanks again guys, i grabbed another relay hopefully it'll be smooth sailing!

Vince

ken1959, I agree with your post 100%. The when the ac compressor turns on, whatever fan is to cool the condenser should come at the same time, for the reasons you mentioned.

Agentjam's post says that the radiator fan currently does comes on when the when the ac compressor is turned on AND when th temp sensor activates  .  So his radiator fan activation seems to be working correctly, as per your suggestion. 

The impression I got from his post is that his additional ac condensor fan was not currently hooked up to anything.  The diagram I posted was a very simple hookup to turn on the extra ac condensor fan when the radiator fan comes on, either with the temp sensor or when the ac compressor turns the radiator fan on.  The 12v to the relay must be tapped to the radiator fan output source after whatever temp sensor or ac compressor activation is currently controlling the radiator fan.

It wasn't my intent for him to rewire the fans completely with the diagram I posted,  but rather to use it to simplfy the activation of the supplemental ac condensor fan.