How to test electric fans?

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Jun 28, 2017 | 11:26 AM

wave1957

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How to test electric fans?

I have a '70 Impala with a 2005 Magnacharger-blown LQ9. The car has twin electric fans from an early '80s Chrysler sedan.
A few days ago, I could not hear the fans, the temp when a bit high, but OK and the fans never started.
I figure it is not caused by the engine sensor since the engine would not run well and the check engine light would come on. So I guess I am going to check connectors, relays...
My problem is, how do I check that the circuits work fine, each time I giggle a connector, without each time running the engine 1/2 an hour to warm up and (hopefully) trigger the fans?

Jun 28, 2017 | 12:27 PM

pantera_efi

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From: Santa Ana, CA. USA

CLT Sensor Connector

Hi, most sensors report "on" with LOW resistance or "0" Ohms.

Remove the sensor connector then short the two pins with a wire.

BE CAREFUL not to expand the terminals.

Lance

Jun 29, 2017 | 08:36 AM

JoeNova

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From: Ohio

Have HPTuners? You can manually cycle the fans on from the scanner.

Jun 30, 2017 | 03:19 PM

s14hunter

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From: KS

If you're running a 3-relay setup for your fans, you can use the schematic below to trigger the relays and see if the fans come on.
-Turn the key to the RUN position
-Use a jumper wire to ground pin# 85 on all 3 relays (two of them are already connected together)
-Fans should come on full speed.

If the relays click when you ground those terminals and the fans don't come on, the fans are shot.
If the relays don't click, you either have a bad relay(s) or a fuse/wiring issue.

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