Date: Sat, 22 Aug 2015 20:09:38 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: Radiator Aux Cooling Fan 84 vs. 90
In-Reply-To: <000101d0dd36$4be5aca0$e3b105e0$@net>
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I guess if it's on the Samba it must be true. The radiator fan switch senses the water temperature in the radiator closer the outlet than inlet. A higher temp thermostat will make less coolant flow until it fully opens allowing the radiator more time for it to cool. It is true that too low a temp fan switch will run the fan needlessly. A 75c switch is ridiculous. In hot weather with a good load you will never get the coolant temp that cool so the fan goes forever. If you use the AC the fan will run for the compressor anyway. If in this situation the radiator switch calls for the fan above that the radiator is either saturated with heat due to extreme conditions including it may not be good or the fan switch is too low.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Jack Reynaert
Sent: Saturday, August 22, 2015 7:57 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Radiator Aux Cooling Fan 84 vs. 90
Dennis and everyone else,
Thank you for your great information.
PS... was thinking about the low-temp switch, but just saw this on TheSamba.
"Just remember that the fan switch needs to be matched with the thermostat. If you run the low temperature fan switch with a higher than stock thermostat the fan may well run too often."
Jack
-----Original Message-----
From: Dennis Haynes [mailto:d23haynes57@hotmail.com]
Sent: Saturday, August 22, 2015 4:31 PM
To: 'Jack Reynaert'; vanagon@GERRY.VANAGON.COM
Subject: RE: Radiator Aux Cooling Fan 84 vs. 90
The wiring and operation of the 90 is drastically different than in the 84. The fan motor is much larger, one speed using a resistor to provide lower speeds and multiple relays for control. Also depending on variations some will have the cooling fan low speed operation effected or even disabled if the AC wiring is hacked. Here is a brief summary of expected operation.
Engine cooling
When radiator fan switch calls for low speed cooling the switch directly supplies power from the fuse block through the resistor to the motor.
When same switch calls for high speed there is a relay above the fuse box. This relay brings power directly from the battery (own wire) through a fusible link directly to the fan motor. A failed fuse for the control and low speed disables both these systems.
To support the Air conditioner
When the compressor is on the fan runs at a low speed energized from a relay in the AC system. This also depends on the fan resistor.
If system (AC) high side pressure increases due to insufficient cooling a pressure switch operates a relay in the fuse box to increase the radiator fan speed. Basically the other side of the fan resistor is placed in parallel increasing current flow and thus fan speed.
If pressure continues to climb at some point the AC will get cut out and the fan will still run at the higher speed until it drops.
There are number of different pressure switch set ups. Most of the late vans use a single switch with multiple function often known as a trinary switch.
Trinary switch functions
Low pressure (lost charge) cut out.
2 speed condenser (radiator) fan.
High pressure cut out.
The 84 has none of these features or safeties. They just self-destruct when things go wrong.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Jack Reynaert
Sent: Saturday, August 22, 2015 2:25 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Radiator Aux Cooling Fan 84 vs. 90
When I run the AC on my 84 Westy, the Aux. fan on the Radiator runs as long as the power is on to the AC in back (regardless if the compressor is on).
When I'm stuck in traffic, and the temp gage rises, the Aux fan does not kick-on by itself. So, I turn on the AC, without compressor, and the fan kick's on and the temp gage goes down. I suspect the temp sensor on the radiator is bad, and plan to change it.
Now, my question is related to the Aux radiator fan on the 90 Westy we are just about complete with the mechanical overhaul (including new 2.2 GW motor, brake system, radiator, condenser, LED upgrades, dash rebuilt with AWESOME GW Kit, new everything that attaches to the GW motor as well).
We took it for a ride today, and even at full operating temperature, the aux fan didn't kick on. Put 12v to the fan motor and it worked fine, fuse #1 fine, power to the red/white wire to the switch etc. However, when we turned on the AC, the aux fan didn't turn on (like it does on my 84)... is that normal for a 90?
Any suggestions on likely causes (relay #53 or temp. sensor lower drivers side of radiator?)
Thanks for any insight!
Jack R.
N. of Detroit
