Re: 505 Turbo Auto Cooling Fans Relay

George Nunez (ganunez@adelphia.net)
Sat, 27 Jun 1998 20:35:48 -0400

I highly recommend getting the 505 electrical workshop manual( try Voss
Motors in the clubs resources page). The auto has 2 fans that are in a
series parallel circuit to change speeds. This circuit has 3 relays, 2
diodes, the rad switch and the trinary switch.
I`ll try to explain.
Relay A may be energized from the a/c diode or rad switch diode(190F
contact), result is low speed on both fans.
Relay A feeds fan 1, then returns thru a relay B to feed fan 2 (series)
then on to ground.
If rad switch is over 198F or trinary is over 275 psi, relay B is energized
so that fan 1returns thru B to ground. AND relay C is energized to feed fan
2.
Note that the rad switch has a contact that closes at 190F AND another that
closes at 198F.
In other words: relay A closes at 190F(or A/C on), the other two relays
close in addition to A at 198F(or 275psi from trinary)
Good Luck,
George N.

visit my web site at: http//:www.geocities.com/motorcity/track/4889/
-----Original Message-----
From: davidtowle@lycosmail.com <davidtowle@lycosmail.com>
To: Post <Peugeot@padui.org>
Date: Saturday, June 27, 1998 1:11 AM
Subject: 505 Turbo Cooling Fans

>At the Rendezvous I got some help from Brian and Steve to solve what I
thought was a small cooling fan problem, but now that I've looked the
problem appears bigger and I'm more confused about what does what, so here's
the situation:
>
>On my 87 turbo 505 SW, it appears I have only one out of three cooling fans
working properly and have for some time, that shows a good level of
overdesign! The right side electric fan operates at both low and high
speed. The left side one works on low speed only, then shuts off when the
other goes to high speed. Both operate only with the AC on, no matter how
hot or cold the engine. The solenoid clutch main fan works fine when I
apply 12 volts with the engine off, but with the engine at idle works only
about 2% of the time.
>
>Brian and Steve thought the high speed fan problem was due to a bad relay
in the relay box in the left fender, and indeed one was icky with green goo
coming out so I ordered one from the dealer (cheaper than a generic one of
unknown amperage from a discounter) but don't have it yet. Any ideas why the
solenoid works at rest but not when rotating at idle?
>
>In trying to troubleshoot this problem, I have been unable to figure out
what switch does what. Can anyone tell me? My thermostat has 5 thermal
switches or indicators coming out of it, one small red plastic hex with one
wire, one large plastic hex with two wires, one metal hex with two wires,
one blue plastic rectangular one with booted wires (unknown quantity), and a
similar red plastic one. Plus the right side of the radiator has two wires
coming out, but that appears to be a coolant level switch. I don't know why
there's so many switches when the electric fans just seem to run off the AC
anyway.
>
>Thanks, Dave Towle
>
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