2000 Ford Taurus Momentary 200 RPM idle increase

KENLOVESJENN

MEMBER
2000 FORD TAURUS
6 CYL
2WD
AUTOMATIC
16,000 MILES

With the heating/cooling fan on, idle surges by just under 200rpm every 3 seconds. Fan only works when speed selector switch is in highest speed setting. I pulled switch to attempt repair, it looks like it got hot at some point. I'm pretty sure the rpm surge didn't start as soon as I lost other speed settings, but I guess I'm not 100% on that.

Thursday, May 20th, 2010 AT 8:56 PM

3 Replies

BMRFIXIT

MECHANIC
19,053 POSTS

Check AC system if low as if maybe the AC compressor engaging and disengaging
that will cause the RPM to flex up and down

as for the fan
suspect, check and replace blower motor speed control resister located beside blower motor at the passenger side

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Thursday, May 20th, 2010 AT 9:54 PM

KENLOVESJENN

MEMBER
7 POSTS

Yeah, AC system is definitely low. Today as I was driving, I started to smell a horrible burning - it was the AC compressor. Guess I'll replace it and charge the system. As for the resistor - is that what probably took out the fan speed switch? Is it as easily tested as, say, a 5k ohm resistor in a circuit - just measure resistance? Does it say what the resistance should be? And, finally, is it accessed through the engine compartment at the firewall as I would assume? Thank you very much for your response!

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Tuesday, May 25th, 2010 AT 10:15 PM

BMRFIXIT