When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a quick and easy question.
I have a vintage air AC system installed with a trinary switch.
The electric fan is hooked up through a relay to the condenser clutch and turns on when the clutch engages, but it is NOT hooked up to a temperature gauge and therefore is that the mercy of the condenser clutch for power.
I want to install a toggle switch to bypass the condenser clutch relay and allow me to turn my electric fan on and off whenever I want.
I have included a picture below of the relay and labelled the wires according to where they connect with the male end. The only one that I know for sure where it goes to is the black wire. As it is visibly grounded to the radiator frame from the female end of the relay.
I simply need to know which wire on the relay to splice into to run a wire to my grounded toggle switch
in order to achieve my fan on and off freedom. Thank you in advance for your help!
Depending upon how it's wired, it may not be possible as you've described the problem. The relay coil terminals are 85 & 86 and it doesn't make any difference which one gets +12v and which one gets ground. I suspect 86 is permanently grounded but only because it's black and 85 receives +12v from the compressor clutch. If that is the case then your best bet is to use a 2nd relay. Typically 30 is used to supply power and 87 is the load. If 30 is supplied with switched power, it's a little easier but it's probably supplied with unswitched +12v (hopefully fused). You can tie the 30's together and the 87's together from both relays. Supply 85 with switched+12v and then ground 86 through your toggle switch. This way the fan will run with the toggle switch or with the compressor and it doesn't matter if both are on. If it were me, rather than a toggle switch, I would add a thermal switch to operate the 2nd relay.
This link ( 901095 Rev D 5 ) is from Vintage Air showing the wiring diagram for the trinary switch. You could install their "Optional Thermostat Switch" shown at the bottom of the diagram or put your toggle switch in that location.
This link ( 901095 Rev D 5 ) is from Vintage Air showing the wiring diagram for the trinary switch. You could install their "Optional Thermostat Switch" shown at the bottom of the diagram or put your toggle switch in that location.
Ted
I appreciate the link, but I also saw that schematic myself.
Unfortunately, I tried splicing the toggle switch in both the 85 and 86 position, to no success. As the last gentleman commented and I mentioned in my original post, the black wire goes from 86 and is permanently grounded to the radiator mount.
I am a complete novice when it comes to electrics and everything I’ve read and all the videos I’ve watched make it seem so plain and simple and easy. I should just have to splice a wire into the system to allow me to break the ground with my toggle switch. I just don’t know where to splice it into
I don’t know why I’m having so much trouble with this. Hopefully someone can chime in with some easy advice or redneck MacGyver-ing…
All your toggle switch can do since one side of the coil is grounded is to make your fan either turn on or not turn on when the compressor requests it --- not what you want. The two relay solution will work perfectly but I don't know how to describe any better than I already have. You mount another identical relay beside the existing one and tie 30 to 30 and 87 to 87. That connects main power and load identically to both relays. Find +12 volts that comes on with the ignition switch and connect it to 85 of the 2nd relay and then connect 86 of the 2nd relay to one side of your toggle switch and connect the other side of the switch to ground. Declare victory.
Plan B: Add a diode to the feed from the compressor on terminal 85 of your existing relay. Anything >= 1 Amp / 100 Volts will be fine. The arrow or bar (cathode) of the diode should point toward terminal 85. Your toggle switch should now be connected to +12 volts that comes on with the ignition switch and the other side should connect to terminal 85. Leave 86 connected as it is. Plan B is more difficult to wire with a thermal switch in that it would now have to do more than simply complete the ground circuit.
Last edited by acstephenson; Yesterday at 01:56 AM.
I don't know what generation VA system you have, but from the information you've provided, it isn't wired like my Gen V system. As acstephenson said, I don't think you can just tap into a wire on the compressor relay. If you notice in the schematic I posted the link to, they have incorporated an "Electric Fan Relay" to operate the condenser fan. I think that's probably what you'll need to do.
All your toggle switch can do since one side of the coil is grounded is to make your fan either turn on or not turn on when the compressor requests it --- not what you want. The two relay solution will work perfectly but I don't know how to describe any better than I already have. You mount another identical relay beside the existing one and tie 30 to 30 and 87 to 87. That connects main power and load identically to both relays. Find +12 volts that comes on with the ignition switch and connect it to 85 of the 2nd relay and then connect 86 of the 2nd relay to one side of your toggle switch and connect the other side of the switch to ground. Declare vistory.
MacGyver, that was very well explained.Thank you very much. I will give that a try and let you know if I have in fact, declared victory. Cheers!
No second relay needed. Splice a wire into the wire on relay pin 85 and run it to one side of your toggle switch. Run the other side of the toggle switch to switched 12v. Done.
I was just re-reading your initial post and you state "The electric fan is hooked up through a relay to the condenser clutch and turns on when the clutch engages". If that is actually what is happening, then your trinary switch is not functioning properly or is mis-wired. The trinary switch is suppose to turn the fan on only when the high side pressure exceeds 254 psi.
My point in post #9 does assume the switch is wired properly. There is no cross feeding as the trinary switch is open between the compressor and the fan. The switch only sends 12v to the fan when ac pressure is too high as Ted says above.
All your toggle switch can do since one side of the coil is grounded is to make your fan either turn on or not turn on when the compressor requests it --- not what you want. The two relay solution will work perfectly but I don't know how to describe any better than I already have. You mount another identical relay beside the existing one and tie 30 to 30 and 87 to 87. That connects main power and load identically to both relays. Find +12 volts that comes on with the ignition switch and connect it to 85 of the 2nd relay and then connect 86 of the 2nd relay to one side of your toggle switch and connect the other side of the switch to ground. Declare victory.
Plan B: Add a diode to the feed from the compressor on terminal 85 of your existing relay. Anything >= 1 Amp / 100 Volts will be fine. The arrow or bar (cathode) of the diode should point toward terminal 85. Your toggle switch should now be connected to +12 volts that comes on with the ignition switch and the other side should connect to terminal 85. Leave 86 connected as it is. Plan B is more difficult to wire with a thermal switch in that it would now have to do more than simply complete the ground circuit.
I picked up a new relay today and have just one question…You say to Thai 30 to 30 and 87 to 87 which I understand. I am wondering how I tie them together?Do I leave all of the wires plugged in to the harness that plugs in to the relay and then tie in new wires into the harness and loop them over to the new relay?Then proceed with the rest of your instructions?I have two relays and one wiring harness and don’t want to mess this up.Again, I appreciate your instructions just looking for a little bit more detail seeing as how I have stated before I am an electrical novice.Cheers!
If it were me, I would unpin 30 on the existing relay, cut the connector off and connect the old wire to power AND a new wire to the other relay's pin 30 and crimp them together and then reinsert the terminal in the original pin 30. Do the equivalent for pin 87. If you don't have extra terminals and a crimper then the next easiest way is to use tap splices.
The idea there is to put the existing pin 30 wiring in the thru connector and then insert the wire from pin 30 of the new relay into the other side of the tap splice so that all three (power, pin 30 of relay 1, pin 30 of relay 2) are connected together. Similarly do pins 87 and the load.
The tap splices can be easily removed if needed leaving the original wiring intact except for a small nick which can be easily taped.
My point in post #9 does assume the switch is wired properly. There is no cross feeding as the trinary switch is open between the compressor and the fan. The switch only sends 12v to the fan when ac pressure is too high as Ted says above.
Well, I hooked it up the simple way you suggested and it turned the fan on finally!However, it also engaged to the condenser clutch as well. Not so good, however, I drive a convertible and have never used that air-conditioning nor will I ever use the air-conditioning because it’s a convertible. So, I simply unplugged the condenser and now the fan runs, and the condenser doesn’t engage!This is exactly why I wanted it from the beginning! Thank you very much for all of your help.
Just a little edification. What you've been referring to as the "condenser" is actually the compressor.
Glad that you were able to achieve what you wanted.
Just a little edification. What you've been referring to as the "condenser" is actually the compressor.
Glad that you were able to achieve what you wanted.
Ted
Learning as I go and always appreciate the knowledge and advice.
Well, I hooked it up the simple way you suggested and it turned the fan on finally!However, it also engaged to the condenser clutch as well. Not so good, however, I drive a convertible and have never used that air-conditioning nor will I ever use the air-conditioning because it’s a convertible. So, I simply unplugged the condenser and now the fan runs, and the condenser doesn’t engage!This is exactly why I wanted it from the beginning! Thank you very much for all of your help.
I’m glad it worked out, but your AC wiring is a bit wonky from my perspective. Anyway, drive on good sir!
Electric Fan Toggle Wiring
