I have a set of electric fans in my 96 chevy, It is a stock set of fans out of an '05 silverado. The two fans are wired each with their own relay, but are connected to the same temp sensor.
What I want to do, is take the smaller 5 blade fan and hook it into the a/c accumulator sensor so when the A/C is turned on the fan comes on. I want to do that over hooking it into the compressor so the fan is on the whole time the a/c is on, and not just when the compressor cycles.
My question is how do I wire the fan to come on, I know I should just be able to tap into it and connect the accumulator sensor wire into the relay activation wire, but I need to use a one way diode so I don't back feed into the a/c wires. Do I need to have a second one way diode on the efan relay trip wire, between the temp sensor and the splice wire, to keep from back feeding the temp sensor and turning on the other fan?
Also, do I need to have a grounded capacitor hooked up to the diodes to absorb excess voltage from the voltage spike caused by turning on/off the a/c system?
I don't know a whole lot about electrical, but I know the basics. I've only seen it mentioned that a capacitor would be needed to absorb voltage spikes.
You should be able to drive a relay off the lt. grn wire at the low press. switch, you will need to check if that is B+ or grounded with a/c on and wire the relay accordingly.
You should not need any capacitors as you are on the control side of everything.
Are you still planning on running both fans when the temp sensor turns them on?
I want to wire one of the relays so the fan comes on with either the a/c or the temp sensor. My thought was that I could leave it as is now, but add a wire from the a/c low pressure switch to the one of the relay activation wires. I thought a diode would keep all the voltages from activating something it shouldn't.
So if the a/c is turned on, it activates the relay and turns the fan on the whole time the a/c is on, and not just when the compressor cycles. If the a/c is off, and the temp sensor reaches temp (200*), that will still turn the same fan on, but the diode would keep the signal from back feeding into the a/c system.
Basically, i want the system to still turn both fans on with the temp sensor (eventually, I'll get a second temp sensor to wire the other fan to), but one fan to turn on with the a/c turned on.
The fan usually runs off of a temp sensor or pressure switch on the compressor discharge. The switch on the accumulator is the compressor cycle switch to bring the compressor on and off. I don't recommend omitting either of these.
The fan usually runs off of a temp sensor or pressure switch on the compressor discharge. The switch on the accumulator is the compressor cycle switch to bring the compressor on and off. I don't recommend omitting either of these.
He is talking about using the siginal to turn a fan on.....not doing away with it.
This truck the HVAC controller sends an a/c request signal (B+ I think) thru the cycling switch and high press. cut out to the pcm.....the pcm then runs the compressor. I don't think he would have an issue running a relay off the a/c request signal before either switch. he may need a diode if he is gonna run both fans when coolant temp switch turns on the other fan/relay.
As long as the a/c request signal (should be lt. grn wire on the low press switch) is B+ and your relays are B+ triggered..... you can wire the relay trigger wire to the lt. grn wire with a diode to the switch and a diode between relays and it should work.
So, i should be able to to run a relay but instead of it sending power, it'll connect the fan to ground, (the a/c signal trips the relay and completes the relay path to ground), and the diode will keep the other fan from having a path to ground when the a/c is on, right?
Not to keep asking the same question, but I want to make sure i have this right. I picked up a new relay with wiring harness, but I didn't think when i bought it. It's the same type for my efans.....if I wire everything to ground (fan wire and power wire [which will be hooked to ground]) then hook up the wire meant for an ignition power to the sensor wire; that would get the desired result correct?
So instead of the ignition wire being wired to ignition power, it gets wired to the power side of the pressure sensor, so the relay only has power when the sensor is activated. The fan wire is connected to the fan harness, and red power wire connected to ground, and the sensor wire connected to ground, so essentially the relay is always "activated" but only works with the 'ignition/sensor' power
Sounds right, look on the relay....normally they have a diagram like the one I drew above with terminal numbers then you can match what I have up there.
So, I decided to finally wire everything up today, got the relay wire right, but I think my diodes are either bad or the wrong ones.
Both fans turn on with the a/c switch on, I thought I had the diode backwards but it doesn't seem to be doing anything other than conducting. Switch the diode around and still the same. I decided to just leave the one temp probe wire disconnected so one fan runs on the temp probe, and the other just on the a/c switch.
Not how I wanted it to run, but I need to find the right diode to put in place.
The ones I got are 1N4001, I thought those were the ones I needed but apparently not
Any advice would be great, I don't see how else the other fan could be back fed. I'm running a relay off of another realy, the only connection to both fans in the one temp sensor, since both fan relays are connected on the same point to the temp sensor
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