High spped fan issue - 1996 Z28
08-12-2005, 10:35 PM
#1
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Join Date: Nov 2004
Posts: 7
High spped fan issue - 1996 Z28
I have been trooubleshooting this for a while now...
The high speed cooling fan on my 1996 z28 does not seem to come on when it used to. I have had the cooling system inspected, and the high speed fan can be triggered through the diagnostics port, but it no longer comes on when the A/C is turned on. It does come on, but usually only when I am stopped or idle.
So the behavior is like this:
(While driving)
Temp > 240 (no fan, but it does not overheat)
Turn A/C on (still no fan)
(Stopped and running)
Temp > 240 (High speed fans turn on, temp cools to 210)
Turn A/C on (still no fan)
The car will not overheat, but the temp gets up to the last notch before the red at times.
I am relatively sure the high speed fan came on everytime I turned the A/C on, but maybe this is not correct.
Any info is appreciated...
JR
The high speed cooling fan on my 1996 z28 does not seem to come on when it used to. I have had the cooling system inspected, and the high speed fan can be triggered through the diagnostics port, but it no longer comes on when the A/C is turned on. It does come on, but usually only when I am stopped or idle.
So the behavior is like this:
(While driving)
Temp > 240 (no fan, but it does not overheat)
Turn A/C on (still no fan)
(Stopped and running)
Temp > 240 (High speed fans turn on, temp cools to 210)
Turn A/C on (still no fan)
The car will not overheat, but the temp gets up to the last notch before the red at times.
I am relatively sure the high speed fan came on everytime I turned the A/C on, but maybe this is not correct.
Any info is appreciated...
JR
08-12-2005, 11:26 PM
#3
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Thread Starter
Join Date: Nov 2004
Posts: 7
Re: High spped fan issue - 1996 Z28
(continued from the above post)
I recently had these replaced too:
coolant temperature sensor
thermostat
waterpump
One mechanic did say I should have the radiator replaced, but another said it was ok. I should also mention that the temperature does come down ultimately while driving (it never gets up to the red), but I know that turning the A/C on used to turn the high speed fan on no matter what.
Question: I have been reading other posts about a manual fan switch, and I found the very nice schematic from shoebox, but I am confused. I thought the PCM leads provided voltage to the fan relays? The schematic makes it look like the switch would bring that lead right to ground. Maybe I am not reading that right...
Thanks,
JR
I recently had these replaced too:
coolant temperature sensor
thermostat
waterpump
One mechanic did say I should have the radiator replaced, but another said it was ok. I should also mention that the temperature does come down ultimately while driving (it never gets up to the red), but I know that turning the A/C on used to turn the high speed fan on no matter what.
Question: I have been reading other posts about a manual fan switch, and I found the very nice schematic from shoebox, but I am confused. I thought the PCM leads provided voltage to the fan relays? The schematic makes it look like the switch would bring that lead right to ground. Maybe I am not reading that right...
Thanks,
JR
08-12-2005, 11:44 PM
#4
Registered User
Thread Starter
Join Date: Nov 2004
Posts: 7
Re: High spped fan issue - 1996 Z28
Thanks for the link to your site shoebox...lots of useful information!
I could have sworn that the high speed fan came on with the A/C, but maybe not. I think the connection I am making is that the car would always run cooler (coolant temperature) when the A/C was on, and now it doesn't.
JR
I could have sworn that the high speed fan came on with the A/C, but maybe not. I think the connection I am making is that the car would always run cooler (coolant temperature) when the A/C was on, and now it doesn't.
JR
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