Fan blower won't shut off, on continuously. 2000 Grand Marquis 4.6

BC

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MAKE:Mercury
MODEL:Grand Marquis LS With electronic instrument cluster
YEAR
:2000
MILES:90,000
ENGINE
:4.6
DESCRIBE ISSUE.... A/C fan blower is stuck on continuously. Fan is on no matter what position you place climate control position in. It stays on even when turning the switch in the OFF position. The only thing I notice is when moving the fan speed dial, blower operates in two speeds...medium and high, placing it in low blowers stays on medium. A/C blows cold air okay.

I checked for relays under the hood but nothing is marked.

Thank you!
BC
 
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Jim Fairbanks

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Try the #3 relay in the box under the hood...swap it with one of the other ones that are the same and see if it does anything...Jim
 

BC

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Try the #3 relay in the box under the hood...swap it with one of the other ones that are the same and see if it does anything...Jim
Found #3 and checked relay with meter, swapped relays, and pulled all of them completely out and the fan keeps on running. There is power going to the #3 relay, but pulling it out didn't change anything. I also jumped the relay with power across the connectors and rechecked with meter and they're all working.
Now I'm :confused:
 

Mobile Dan

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Maybe a bad blower resistor...looks like a challenge to access. I would be very gentle with the hose to the engine.
 

billr

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Does this use resistors, or one of those neato PWM modules?
 

BC

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So this resistor could malfunction in a way that the motor could continually run? I'll head in that direction if that's the case.
Thanks,
BC
 

nickb2

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Hol$t Mobile, dan. Me thinks the resitor is in the conector, write where your hand is. Here is to garage hands like mobile, bill, Jim(my favorite appart from Bill) cuz they will give the time of day.

Kev2, BP, and so many others. I am going windows 10. Here is me knuckling. :giveup:I don't think my old OBD2 software will do so this laptop is a test.

So to Mobile Dan, dance to this
 

billr

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Well, I think the resistors usually fail so that the motor doesn't run at all, a PWM module is more likely to fail so that the motor won't turn off... that's why I'm curious if it is PWM.

Edit: Looking at rockauto, it seems this does have resistors. I still doubt they are causing a continuous run.
 

nickb2

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I wish the search function worked better, cuz I posted a wiring for this, guess my fat knuckles scrap laptops too,

update, meybe my other I7 will take the database, but will wipe everthing and post back until all is on line. Until then any tips on transition from, damn lost translatione again. Fu%k it again here goes how I feel when this happe$ns.

 

nickb2

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PCM runs ground, or relay, you need to check schematics and listen to rammestien, cuz there is only one option here, resister blew, and yoy need new fan assembly or oin test wiring to see where you missed the ground. Cuz if it runs, it has power.!!!!!!!!!!!!!!!
 
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