Tpi/ac
Thread Starter
Supreme Member
Joined: Aug 2001
Posts: 2,747
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From: Orygun
Tpi/ac
Hey guys,
Just wondering on an 86-89 TPI car what conditions within the ECM call for the fan to be turned on? is it ONLY via the coolant temperature? or does AC effect it? My fan stays on and wont go off
thanks
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Just wondering on an 86-89 TPI car what conditions within the ECM call for the fan to be turned on? is it ONLY via the coolant temperature? or does AC effect it? My fan stays on and wont go off
thanks
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Supreme Member
Joined: Jul 1999
Posts: 5,183
Likes: 42
From: Oakdale, Ca
Car: 89 IrocZ
Engine: L98-ish
Transmission: 700R4
On my '89...
Primary fan controlled by CTS input to the ECM, ECM then energizes the primary fan relay to turn the fan on.
2ndry fan is controlled via fanswitch in the pass side head, FS grounds the 2ndry fan relay, and enrgizes both fans.
2ndry fan relay is also contorlled via high pressure switch in the A/C system, but the signal *may* run through the ECM, not sure, reason I mention this is I don't think the fans can come on if going over a certain speed as seen by the VSS. Dunno, something to look into some day when they quit working again
Primary fan controlled by CTS input to the ECM, ECM then energizes the primary fan relay to turn the fan on.
2ndry fan is controlled via fanswitch in the pass side head, FS grounds the 2ndry fan relay, and enrgizes both fans.
2ndry fan relay is also contorlled via high pressure switch in the A/C system, but the signal *may* run through the ECM, not sure, reason I mention this is I don't think the fans can come on if going over a certain speed as seen by the VSS. Dunno, something to look into some day when they quit working again
Senior Member
Joined: Dec 2000
Posts: 886
Likes: 0
From: Raleigh, NC, USA
I think the sensor is internal to the AC system.
Since the fan's staying on all the time, that means the green wire running from the fan is being grounded when it shouldn't be. Look for anything unusual, for example, if there's a wire running from the fan to an engine ground, and it's obviously NOT stock...
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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else
Since the fan's staying on all the time, that means the green wire running from the fan is being grounded when it shouldn't be. Look for anything unusual, for example, if there's a wire running from the fan to an engine ground, and it's obviously NOT stock...
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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else