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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
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Fan Always Runs on High

  • Thread starter Thread starter revhead347
  • Start date Start date Aug 21, 2010

revhead347

Apparently my ex-husband made that mistake.
20+ Year Stangneter
Jun 14, 2004
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Acworth, GA
Aug 21, 2010
#1
  • Aug 21, 2010
  • #1
Got a problem on a friends 94' Cobra. The radiator fan always runs on the high speed. Doesn't matter whether the AC is on or off. As soon as the car starts up, the fan is running on high. We tried swapping out the coolant temp sensor. Anyone know a common problem that could cause this?

Kurt
 

toyman

10 Year Member
Jul 19, 2007
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Aug 21, 2010
#2
  • Aug 21, 2010
  • #2
revhead347 said:
Got a problem on a friends 94' Cobra. The radiator fan always runs on the high speed. Doesn't matter whether the AC is on or off. As soon as the car starts up, the fan is running on high. We tried swapping out the coolant temp sensor. Anyone know a common problem that could cause this?

Kurt
Click to expand...

Stuck relay in the CCRM? Try giving the CCRM a smack to see if the relay will release. The ECT sensor is on the heater bypass housing (passenger side of engine). Fault codes will be 116,117 or 118.
 

revhead347

Apparently my ex-husband made that mistake.
20+ Year Stangneter
Jun 14, 2004
9,297
1,641
214
Acworth, GA
Aug 21, 2010
#3
  • Aug 21, 2010
  • #3
Cool. It probably is the CCRM, because the car isn't throwing any codes. Either that, or the computer has gone bad, which is highly unlikely.

Kurt
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
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Aug 22, 2010
#4
  • Aug 22, 2010
  • #4
Did someone do a manual fan switch or otherwise ground CCRM Pin 17?
 

revhead347

Apparently my ex-husband made that mistake.
20+ Year Stangneter
Jun 14, 2004
9,297
1,641
214
Acworth, GA
Aug 22, 2010
#5
  • Aug 22, 2010
  • #5
HISSIN50 said:
Did someone do a manual fan switch or otherwise ground CCRM Pin 17?
Click to expand...

No, it just started happening. I guess I need to check to see if the signal wire from the computer to the CCRM is showing any voltage when the car is cold. And if not, then it has to be the CCRM.

Kurt
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Aug 22, 2010
#6
  • Aug 22, 2010
  • #6
As mentioned, you actually want to check that wire for continuity to ground, not 12V.
 

revhead347

Apparently my ex-husband made that mistake.
20+ Year Stangneter
Jun 14, 2004
9,297
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Acworth, GA
Aug 23, 2010
#7
  • Aug 23, 2010
  • #7
HISSIN50 said:
As mentioned, you actually want to check that wire for continuity to ground, not 12V.
Click to expand...

Clearly my knowledge base is not very good on how the system works. I assumed there would be a 12v power going to the relay to turn the fan on. Any other insights on the fan system would be greatly appreciated.

Kurt
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Aug 23, 2010
#8
  • Aug 23, 2010
  • #8
Yeah, you'd think so Kurt but it's EEC controlled and kinda funky. The low-speed relay gets a 12V signal (Pin 14 at the CCRM) but high speed uses a ground pulse. The EDF monitor is also a possible factor when things act up.

Just in case there's something helpful, here's some info:

94-95 Mustangs Electrical CCRM - Mustang-Tech
 

revhead347

Apparently my ex-husband made that mistake.
20+ Year Stangneter
Jun 14, 2004
9,297
1,641
214
Acworth, GA
Aug 23, 2010
#9
  • Aug 23, 2010
  • #9
Thanks for posting that. We should be able to trouble shoot it with that.

Kurt
 
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