Tom - if you search the forum there are plenty of previous discussions on this subject. You have the relays/controlers like the ones from 'flex-a-lite', but you DEFINITELY don't want to use toggle switches in line with the existing wiring. Way too much amperage. An easy, less complex solution is to remove the IRCM relay box from behind the passenger headlight (in front of the air filter) cut line #14 and splice the tail from the relay box end onto #17, that breaks the ground on the low speed fan and makes it run continuously (if you put spade connectors on both ends you can cancel that in the winter by just connecting it back up again). The reason for splicing it onto #17 (which is the high speed fan) is that should your coolant temp. climb high enough to bring the faster fan winding on it will automatically cut off the low speed; as you don't want both energized at the same time. During the summer the low speed comes on with a/c use but goes off again once you reach highway speed (about 47mph). That's why you suddenly see the temp. guage rise even though you are cruising along. Disconnecting it in the winter restores the stock settings and reduces the battery draw at start-up, otherwise that fan runs as soon as the ignition is on. Additionally you can put one of those adjustable stats on the high speed wiring, by splicing on another wire to #17 and running it to ground thru an adj. stat. On mine I simply have a 200 deg. sensor on the radiator and that grounds/brings on the high speed. However, I've found with the low speed running all the time my high speed hardly comes on.
I learnt the hard way by just having the sensor on the high speed and that current draw alone fried my fuse box. Now the low speed to high speed change-over is far less demanding on the circuit. Strangely enough my '93 has a fuseable link on the fan wiring and I've never had any problems, yet it fried my '94 which was fused thru the under hood box. Now of course I use a separate fuseable link for the '94 as a safeguard.
Hope that's not too confusing,
JIm.