Wire up condenser fan in parallel with compressor? - Alfa Romeo Bulletin Board & Forums
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post #1 of 6 (permalink) Old 09-06-2019, 07:58 AM Thread Starter
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Wire up condenser fan in parallel with compressor?

If I only have a binary switch in my GTV6, is it safe to splice a secondary relay into the circuit from the binary switch to the compressor to trigger the condenser fan I installed?

I also think the passenger side radiator fan is designed to switch on with the compressor, so maybe I should use that existing circuit for the condenser fan and just wire the second rad fan in series with the primary rad fan?

Hmmm...

as good as a car can be... briefly.
'82 GTV6
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post #2 of 6 (permalink) Old 09-06-2019, 08:38 AM
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I'm no AC expert but I think that you need to have pressure switches in the compressor circuit.

Ed Prytherch
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post #3 of 6 (permalink) Old 09-06-2019, 08:43 AM Thread Starter
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Well, I do have the standard-issue binary pressure switch, which passes power to the compressor. My thinking was to install a second output wire to the switch that would trigger a relay to power the condenser fan. I suppose I could install a trinary switch, but I have NO idea how to install it with the existing wiring, or even what size relative to my receiver/dryer. I just figured the binary switch could do the job?

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'82 GTV6
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post #4 of 6 (permalink) Old 09-08-2019, 03:09 PM
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You can just have the OE relay (Q16 on my Alfa schematics) that turns on the first OE rad fan turn on the condenser fan also. The Q14 relay turns on the compressor clutch. The I1 relay turns on both OE fans when triggered by the radiator thermal switch. Since the I1 relay can turn on both radiator fans simultaneously, the Q16 relay ought to be able to turn on one OE fan and the condenser fan simultaneously.
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Tom Henneka
75 Alfetta GT (Original owner), 92 164S, 86 GTV6
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post #5 of 6 (permalink) Old 09-11-2019, 12:32 PM Thread Starter
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Just because I've seen numerous explanations, likely to dodgy rewiring over the years, the radiator fan (the Q16 you referred to) is supposed to come on whenever the compressor is on, but is just on a separate circuit, although triggered by the same input signal? Then the second fan comes on when the coolant hits a certain temp, and BOTH fans will come on, regardless of whether the AC is on to trigger the first fan, once the coolant temp hits an even higher threshold?
Is the principle behind using Q16 instead of Q14 is possibly the voltage load on the relay being more than the clutch relay is designed for (if it stands to reason I1 has the capacity to power both fans, then Q16 should as well)?
Sorry - just trying to wrap my brain around all of this. I'm definitely "eating the elephant" with this project at the moment.

And I was finally able to track down the GTV6 electrical diagrams (1981-1983) instead of the Molano schematics in my Cardisc set. I ran it through text recognition in Acrobat Pro, which is why the Q's appear as O's. Just FYI. This is how it breaks out:

Q HEAT/VENT - AIR CONDITIONING SYSTEM
01 Heater blower fan
02 Pneumatic pushbutton control for air conditioning
03 Pneumatic pushbutton control for ventilation
04 Heater blower fan control
05 Heater blower fan speed adjustment resistance
06 Switch on flap for heater blower fan
07 Fluid thermostat
08 Electromagnetic coupling pressure switch
09 Minimum pressure switch
010 Maximum pressure switch
011 Compressor electromagnetic coupling
012 Thermoswitch for exclusion of compressor electromagnetic coupling
013 Supplementary conditioner fan
014 Relay for supplementary conditioner fan and electromagnetic compressor coupling
015 Heater blower fan relay
016 Relay for simultaneous control of engine cooling fan and supplementary fan
017 Relay for simultaneous control of engine cooling
electromagnetic coupling and supplementary fan

as good as a car can be... briefly.
'82 GTV6

Last edited by chairmankaga; 09-11-2019 at 01:03 PM.
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post #6 of 6 (permalink) Old Yesterday, 06:20 PM
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Yes to all.

Tom Henneka
75 Alfetta GT (Original owner), 92 164S, 86 GTV6
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