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how to wire aftermarket fan for A/C

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Old Nov 8, 2021 | 09:07 AM
  #1  
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From: Johnson City, TN
how to wire aftermarket fan for A/C

Just got finished wiring a puller fan to replace my clutch fan and it seems to be working perfectly, but I wanted to add a pusher fan on the condenser to make the A/C blow a little cooler. I wired up the switch side of the relay for power to the fan but I cant seem to get it to activate. what makes this complicated is that because I have a microteach ECU, I had to get a buddy of mine to find a way around it. he wired the compressor clutch to the blower motor switch so that whenever you activate the blower motor the clutch comes on. I figured I could splice the wire and use that to power the relay for the fan but that doesn't seem to be working at all.
I tried to find a forum post relating to this but I couldn't find anyone that was trying to wire their fan for the AC, so if anyone has any ideas I'd really appreciate it. I also looked at the stock wiring diagram for the rx7 but I cant make heads or tails of it, even more so because the stock ecu is gone and he had to make that bypass I was talking about.
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Old Nov 8, 2021 | 11:41 AM
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pretty sure relays need two hot wires. one to the a/c to tell it when to come on and one to main power.......you might have the wrong type of relay
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Old Nov 8, 2021 | 12:49 PM
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From: Johnson City, TN
Originally Posted by ATC529R
pretty sure relays need two hot wires. one to the a/c to tell it when to come on and one to main power.......you might have the wrong type of relay
its the right type. I have power running on one side of the switch side but im struggling to get power to the coil. i'll take some pictures next time im in the shop but I had it in series between the blower motor switch and the AC pressure switch and it sounded like it was energizing the coil enough for it to click but still no power to the fan. I thought that splicing the wire and adding a short wire to a separate ground would be enough to finally get it to activate but now its not even doing what it did before.

Last edited by Paulc19; Nov 8, 2021 at 12:52 PM.
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Old Nov 9, 2021 | 04:52 AM
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From: GA
What polarity is the trigger you are trying to use? Hot or ground?

87 fused battery30 to the fan85 trigger input86 opposite of trigger( 12v if the trigger is ground/ground if the trigger is positive)
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Old Nov 9, 2021 | 06:06 AM
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From: Johnson City, TN
Originally Posted by Spider2k
What polarity is the trigger you are trying to use? Hot or ground?

87 fused battery30 to the fan85 trigger input86 opposite of trigger( 12v if the trigger is ground/ground if the trigger is positive)
30 has power, 87 is going to the fan and it has a solid ground, I checked, the switch side is set up. 86 and 85 was wired in series with the blower motor switch which is the same thing that activates the clutch on my car, its located prior to the AC pressure switch, and while it was clicking with that setup it wasn't activating the fan. I I spliced the wire and made a separate ground and now its not getting anything at all.
I did another relay just a few days ago for an electric radiator fan so I know how its supposed to be wired up, I just dont know why the relay was clicking and not activating the coil, and I don't know why its not doing it now. and btw, I did check the relay, it is working. Is there another wire I can take a signal from to make this work?
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Old Nov 9, 2021 | 06:21 AM
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From: GA
Originally Posted by Paulc19
30 has power, 87 is going to the fan and it has a solid ground, I checked, the switch side is set up. 86 and 85 was wired in series with the blower motor switch which is the same thing that activates the clutch on my car, its located prior to the AC pressure switch, and while it was clicking with that setup it wasn't activating the fan. I I spliced the wire and made a separate ground and now its not getting anything at all.
I did another relay just a few days ago for an electric radiator fan so I know how its supposed to be wired up, I just dont know why the relay was clicking and not activating the coil, and I don't know why its not doing it now. and btw, I did check the relay, it is working. Is there another wire I can take a signal from to make this work?
Does it activate when you manually trigger the relay? What do you mean by "in series".
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Old Nov 9, 2021 | 06:41 AM
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From: Johnson City, TN
Originally Posted by Spider2k
Does it activate when you manually trigger the relay? What do you mean by "in series".
yes, when I put power to it, it activates and the fan comes on. what I mean by in series is it doesn't have a separate ground, its in line, or in series with the wire. the wire comes out of the firewall, through the relay, through the AC pressure switch and into the body harness, where it goes from there I'll have to check the stock wiring diagrams.
All I need is a good signal wire I can tap into and run that to the relay. I thought this setup would work but clearly its not.
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Old Nov 9, 2021 | 08:15 AM
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From: GA
Originally Posted by Paulc19
yes, when I put power to it, it activates and the fan comes on. what I mean by in series is it doesn't have a separate ground, its in line, or in series with the wire. the wire comes out of the firewall, through the relay, through the AC pressure switch and into the body harness, where it goes from there I'll have to check the stock wiring diagrams.
All I need is a good signal wire I can tap into and run that to the relay. I thought this setup would work but clearly its not.
WHat are 85 and 86 tied to?
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Old Nov 9, 2021 | 10:19 AM
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From: Johnson City, TN
Originally Posted by Spider2k
WHat are 85 and 86 tied to?
spliced from the signal wire that turns on the compressor clutch. because I have a microtech ECU a buddy of mine had to wire it to the blower switch so whenever the blower motor inside the cabin gets switched on so does the AC.
its fixed now, I found another way to get a signal.
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Old Nov 10, 2021 | 07:08 AM
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Just need to tie 2 wires together to get the compressor to trigger, see below:

Originally Posted by Rob XX 7
Rest of the system aside, such as type of charge, pressure switch, triggering the fan if you have an electric fan, fully operational logicon, etc and so forth

Wiring wise Just tie the BLUE/ORANGE and BLUE/WHITE wires together on the plug where the factory ecu was. I just used a small piece of wire and stuck it in there

My ac still doesnt quite work i have a leak somewhere but it did work pretty good for a little bit .

The amount of time and money i have into this crap makes me sick lol

Last edited by Rob XX 7; Nov 10, 2021 at 07:13 AM.
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