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Volvo Electric cooling Fan
Looking for an electric fan option to cool your radiator?
The 2-speed Volvo fan and relays have become a popular swap.
The fan you need is from a 1990's Volvo 740, 850 or 950 sedan or wagon. The 940 fan is the easiest to remove. It is held in with (2) bolts at the top, and clips at the bottom. Unlike the Ford Taurus fan, the Volvo fan can be removed from the shroud.
(Volvo 940 Wagon)
When you get the fan, you'll need the relays and wiring that come with it. If you don't grab the harness, you'll have a hard time hooking up the fan relay.
(2-Speed electric fan from Volvo 940)
Volvo Fan Relay:
The 2-speed Volvo fans came with relay part # 1398845. Some relays also have part # 3523872 (1992-1997 Volvo 850).
These relays were replaced by P/N 9442933 . Part # 9442933 states that it is for a Volvo 740 (92 and newer), 940/960 (92 and newer), and 850 (all).
The fan relay is the heart of the system because it controls whether the fan runs on high or low.
When mounting the Volvo relay, people have found that a Chevy S-10 relay bracket works, but you need to cut off the 4th tab.
Dual Temperature Switch:
There are (2) dual temperature switches commonly used are:
The most common switch used is the BMW dual temperature switch:
These temperature switches have a M14 x1.5 thread.
14mm x 1.5 to 3/8" Brass Adapter:
Hollister Road offered a brass adapter so you can install this metric threaded switch in to a 3/8" temperature sensor fitting.
This is a brass adaptor for the BMW dual temperature switch and similar fan switches that have 14mm x 1.5 x 14mm deep thread. It turns the 14mm x 1.5 thread into a low profile 3/8" standard American pipe thread and lets you use a the dual temperature switches in one port on a non metric American intake manifold drilled for 3/8" pipe thread.
Hollister Road even offers the BMW temperature switch with the 3/8" adapter:
BWM Temperature Switch Plug:
In addition to the temperature switch, you'll need a plug to connect it to the rest of your fan wiring.
What you'll need is:
BMW P/N 61131378412 -- BMW 90° angle connector
Another option for a dual temperature switch comes from Volkswagen:
VALEO P/N 819769 - Open 95 C / 203 F - Close 84 C / 183 F - Thread Size: 22x1.5; Spanner Size: 29
You'll need a switch housing from a Saab 900 that will be installed in the upper radiator hose. There are a few different temp ranges available in the Volkswagen switch. The common Volkswagen switch turns on low speed at 195 F, and high at 215 F. See the chart at the bottom of the page for a list of vehicles using the Volkswagen temperature switch.
(Saab 9000 temperature switch housing)
(Saab 9000 temperature switch housing with Volkswagen temperature switch)
Wiring Up The Volvo Relay:
The harness on your Volvo relay will have (3) plugs. Looking at the (2) photos above from left to right they are:
Red - High speed to fan
Green - Low speed to fan
Black (not shown) - Ground
Yellow (or white ) - High speed mode from temperature sensor (ground triggered)
Yellow/Green (or Blue ) - Low speed mode from temperature sensor (ground triggered)
Large Red - Power (+) from switched source
In the diagram above, the power for the fan relay was fed through a relay controlled by a switch. Most instructions will tell you to use a 12 volt switch source such as the ignition to only power the fan when the vehicle is running.
However, it's better to run a wire from the battery to a fuse and then a relay. Put a switch in the vehicle that is fed from a 12 volt switched source, so that it will only have power with the ignition on. When you flip the switch, it activates the relay and feeds power from the battery to the Volvo fan relay. This switch would remain 'ON' at all times so that the fan will turn on and off as needed by the engine. THE PURPOSE of the switch is to allow you to turn the fan off during water crossings.
Volvo Dual Speed Fan - Homemade Relay Circuit:
Here is the equivalent relay wiring with two standard Bosch-style relays. Note the primary function is to allow the 2nd (low-speed) relay to disengage when the 1st (hi-speed) relay engages. The relays do not run simultaneously.
Vehicles Using The Volkswagen Dual Temperature Switch: