Adding secondary pusher fan.
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Le Mans Master
Joined: Aug 2017
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From: New Jersey
Adding secondary pusher fan.
Simple as the title says. If I were to mount it to the condenser for extra air flow ac on, and wire it into the fan switch on the compressor (84s are different this way it seems) it should work fine no? My only issue is if it'll kick off while at speed. My thought is it should as the airflow over the condenser will lower the pressure enough to open that switch no? My concern is I don't want the fan on all the time and to become a restriction at speed. My main fan is controlled by the ECM now and it kicks out between 30 and 35mph so I'd imagine at those speeds air flow is greater than that of the fan. Thoughts?
Drifting
Joined: Mar 2006
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From: Wabasha Mn
Simple as the title says. If I were to mount it to the condenser for extra air flow ac on, and wire it into the fan switch on the compressor (84s are different this way it seems) it should work fine no? My only issue is if it'll kick off while at speed. My thought is it should as the airflow over the condenser will lower the pressure enough to open that switch no? My concern is I don't want the fan on all the time and to become a restriction at speed. My main fan is controlled by the ECM now and it kicks out between 30 and 35mph so I'd imagine at those speeds air flow is greater than that of the fan. Thoughts?
Thread Starter
Le Mans Master
Joined: Aug 2017
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From: New Jersey
Thread Starter
Le Mans Master
Joined: Aug 2017
Posts: 6,941
Likes: 1,490
From: New Jersey
Then wire the second fan to the Lt Green wire on the high pressure cut out switch. The lt green wire is hot when the mode switch (or the C68 Controller) is calling for AC. Ie, MAX, NORM, BI-LEVEL, or DEFROST. I don't wire to the dk green compressor clutch wire because as the clutch cycles, so will the fan. Hard on the fan motor, alternator, and especially the relay. The constantly cycling fan will become annoying for its noise, and the idle constantly being affected by the alternator load. The condenser benefits from the increased airflow even when the compressor is cycled off. Fan = ON anytime AC is selected, but clutch is not necessarily engaged, is the way Vintage Air does it. Much easier on electrical components, and better AC performance.
If I were doing this addition, and wanted it mostly for increased AC condenser performance, this is how I'd do it. I would also add the stand-alone control switch in the head for the aux fan, the way the OEM B4P fan is wired. This would add stand-alone redundancy in case of main fan failure for whatever reason. Again, the way the B4P functions. B4P is completely segregated from anything to do with the Main Fan, other than the shared blue wires to the relay coils from CFAN fuse which is hot in RUN.
If I were doing this addition, and wanted it mostly for increased AC condenser performance, this is how I'd do it. I would also add the stand-alone control switch in the head for the aux fan, the way the OEM B4P fan is wired. This would add stand-alone redundancy in case of main fan failure for whatever reason. Again, the way the B4P functions. B4P is completely segregated from anything to do with the Main Fan, other than the shared blue wires to the relay coils from CFAN fuse which is hot in RUN.
If you do the AC and switch controls, you'll need two relays for the aux fan. The lt grn wire is B+, so the other side of the first relay coil is direct to ground. The head switch switches to ground, so the other side of the second relay coil goes to the dk blue wire (hot in RUN) for the Main Fan. The battery source and fan motor outputs of the two relays can be paralleled.
The system cycling switch on the back of the compressor hose seems like a reasonable approach though. But again, if it is running all the time because that's hot comp on i would imagine at speed that fan becomes a restriction no?
Safety Car
Joined: Jun 2017
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From: North Georgia, USA
Simple as the title says. If I were to mount it to the condenser for extra air flow ac on, and wire it into the fan switch on the compressor (84s are different this way it seems) it should work fine no? My only issue is if it'll kick off while at speed. My thought is it should as the airflow over the condenser will lower the pressure enough to open that switch no? My concern is I don't want the fan on all the time and to become a restriction at speed. My main fan is controlled by the ECM now and it kicks out between 30 and 35mph so I'd imagine at those speeds air flow is greater than that of the fan. Thoughts?
You can either run that as an alternate ground path for one of the fan relays (dark green or dark blue wire) or you can add a pusher fan to the front of the condenser.
I often add a pusher fan to S-series pickups and SUVs using that switch and a relay. Sometimes I'll also add the lower temp switch in the head (the 215F on, 200F off one for the third generation Camaro that doesn't list C4 Corvettes in the applications), although on the trucks, if the fan clutch is good, that switch isn't needed.
Safety Car
Joined: Sep 2004
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From: Mission Viejo CA
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Le Mans Master
Joined: Aug 2017
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From: New Jersey
Why do you think the running fan will be more of a restriction that a non-powered fan? As air speed goes up, electrical current to the fan will decrease. A non-powered fan will spin in the breeze, which is obviously a restriction to air flow. How much restriction are you concerned with? Will this affect your quarter-mile times, or how are you measuring this "restriction at speed"? At very high speed, the fan motor will become a generator, which will reduce the load on your alternator!
