Help With Installing Manual Fan Switches For A 98 Gt

98gt559

New Member
Jul 17, 2015
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California
Anybody have any info on how to install fan switches? My cooling fan wont come on since i changed the old one that melted the connector. I got a new thermostat, fan & temp sensor connectors, fan, temp sensors & ccrm, which nothing fixed the problem because the fan still isnt coming on so id rather just be able to turn it on manually.
 
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Just wondering. Have you tested the fan ground back to battery negative? Seems to me like a reasonable possibility of a bad connection after the connector got so hot that it melted. Further it's a spot with recent work.

Does grounding CCRM pin #17 (LG/P) wire cause the high speed fan to work? The fan is on an "always on circuit" so all that's needed for this test is a scrap piece of wire to jump pin #17 to a known good ground.

Note, if it does, that proves the basic function of the HS fan and CCRM. Further it offers an easy way to do what it is that you want to do. This method also has the advantage that HEAVY duty wiring and/or relays aren't needed. As a reminder that the fan can draw in excess of 50 amps. Not a job for a light weight switch or relay.

However. Be forewarned that the Mustang's fan control logic is quite sophisticated. Forcing the fan to run all the time will delay motor warm up. During periods of cooler temperatures, will likely make the motor run cold. During cool weather will may also cause the AC suction pressure to drop too low thus causing the AC to short cycle.

The PCM also turns off the fan above 45 MPH. This saves fuel and prevents the fan from becoming a generator.
 
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I havent tested the fan ground back to battery, the farthest i went with testing the fan was just seeing if the high & low speed worked. And i never tested the ccrm either. I just figured that since the new one i bought still didnt fix anything then its probably a problem i cant fix. I also dont plan to have the fan running all the time, only to keep it from overheating since its the only car i have and school is starting in 2 weeks.