New guys needs cooling fan help
Thread Starter
Racer
Joined: Aug 2011
Posts: 494
Likes: 138
From: Chesapeake, VA
New guys needs cooling fan help
Hi everyone,
I dragged home a '90 L98 auto White/Red Sunday. It has been sitting for most of a year. It does run and drive but needs some work.
1st issue though is the cooling fans won't come on. I have the service manual and the elec supplement, but no scan tool.
I have gone through everything I could find in both regarding fans. I can disconnect the plugs at the relays and jump wires the fans will spin. I can make the relays click by applying power/gnd to the terminals.
I replaced the CTS with a brand new one today. the fans will not come on I let the temp guage get up to what looked like 245f. Oil temp just starting to rise.
A/C clutch won't enage - don't know if out of freon or compressor dead yet. but lower fan doesn not turn when I turn the A/C switches on.
I am very experienced on cars, etc but am a little stuck on this problem.
Could the relays still be bad? Please advise - thanks
EDIT: Update - I have the cheap scan tool which flashes the CEL. Codes give are 12, 32, and 44 (it does have headers and hi-flow cats).
***The weird thing is when the scanner is plugged in both fans operate with key on.
Rick
I dragged home a '90 L98 auto White/Red Sunday. It has been sitting for most of a year. It does run and drive but needs some work.
1st issue though is the cooling fans won't come on. I have the service manual and the elec supplement, but no scan tool.
I have gone through everything I could find in both regarding fans. I can disconnect the plugs at the relays and jump wires the fans will spin. I can make the relays click by applying power/gnd to the terminals.
I replaced the CTS with a brand new one today. the fans will not come on I let the temp guage get up to what looked like 245f. Oil temp just starting to rise.
A/C clutch won't enage - don't know if out of freon or compressor dead yet. but lower fan doesn not turn when I turn the A/C switches on.
I am very experienced on cars, etc but am a little stuck on this problem.
Could the relays still be bad? Please advise - thanks
EDIT: Update - I have the cheap scan tool which flashes the CEL. Codes give are 12, 32, and 44 (it does have headers and hi-flow cats).
***The weird thing is when the scanner is plugged in both fans operate with key on.
Rick
Last edited by RedTRex; Aug 30, 2011 at 09:57 PM.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
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Codes 12, 32, and 44 are: No reference pulses, EGR Diag, and O2 Lean respectively.
The main fan is controlled by the computer (ECM) while the aux (front) fan is controlled by a switch in the DS cylinder head between plugs 1 & 3. It's odd that neither will work but the temps do have to be high.
On my 89, the main fan is programmed to come on at 225-deg. The aux fan is higher around 238. Fans will run with a scanner (or tuning equip) attached because it puts the ECM in diag mode. Because the fan(s) do run, that's a good sign. Relays sound functional.
With so many fans not working (in and out), I have to ask if you've checked all your fuses?
Using the scan tool, reset codes to see what comes back.
The main fan is controlled by the computer (ECM) while the aux (front) fan is controlled by a switch in the DS cylinder head between plugs 1 & 3. It's odd that neither will work but the temps do have to be high.
On my 89, the main fan is programmed to come on at 225-deg. The aux fan is higher around 238. Fans will run with a scanner (or tuning equip) attached because it puts the ECM in diag mode. Because the fan(s) do run, that's a good sign. Relays sound functional.
With so many fans not working (in and out), I have to ask if you've checked all your fuses?
Using the scan tool, reset codes to see what comes back.
Thread Starter
Racer
Joined: Aug 2011
Posts: 494
Likes: 138
From: Chesapeake, VA
Sorry sir your comment doesn't make sense.......I am trying to get the fans to run when they should. I have tested them as I stated above. Please clarify what you mean.
and thinking out loud - could I have a ground problem (G106 maybe). The scan tool is creating the ground between blk/wht and wht/blk at the ADL? That is why the fans run with it inserted?
Only other thing I can is ECM bad.....
Granted I am new and have limited knowledge on this car at this point.
and thinking out loud - could I have a ground problem (G106 maybe). The scan tool is creating the ground between blk/wht and wht/blk at the ADL? That is why the fans run with it inserted?
Only other thing I can is ECM bad.....
Granted I am new and have limited knowledge on this car at this point.
Thread Starter
Racer
Joined: Aug 2011
Posts: 494
Likes: 138
From: Chesapeake, VA
Thanks for the info.
I have the service manual, I understand code 12 should always show?
Anyway, 90 only has 2 puller fans.
Should the temp guage just about peg out before the fan(s) come on?
I have the service manual, I understand code 12 should always show?
Anyway, 90 only has 2 puller fans.
Should the temp guage just about peg out before the fan(s) come on?
Codes 12, 32, and 44 are: No reference pulses, EGR Diag, and O2 Lean respectively.
The main fan is controlled by the computer (ECM) while the aux (front) fan is controlled by a switch in the DS cylinder head between plugs 1 & 3. It's odd that neither will work but the temps do have to be high.
On my 89, the main fan is programmed to come on at 225-deg. The aux fan is higher around 238. Fans will run with a scanner (or tuning equip) attached because it puts the ECM in diag mode. Because the fan(s) do run, that's a good sign. Relays sound functional.
With so many fans not working (in and out), I have to ask if you've checked all your fuses?
Using the scan tool, reset codes to see what comes back.
The main fan is controlled by the computer (ECM) while the aux (front) fan is controlled by a switch in the DS cylinder head between plugs 1 & 3. It's odd that neither will work but the temps do have to be high.
On my 89, the main fan is programmed to come on at 225-deg. The aux fan is higher around 238. Fans will run with a scanner (or tuning equip) attached because it puts the ECM in diag mode. Because the fan(s) do run, that's a good sign. Relays sound functional.
With so many fans not working (in and out), I have to ask if you've checked all your fuses?
Using the scan tool, reset codes to see what comes back.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Sorry sir your comment doesn't make sense.......I am trying to get the fans to run when they should. I have tested them as I stated above. Please clarify what you mean.
and thinking out loud - could I have a ground problem (G106 maybe). The scan tool is creating the ground between blk/wht and wht/blk at the ADL? That is why the fans run with it inserted?
Only other thing I can is ECM bad.....
Granted I am new and have limited knowledge on this car at this point.
and thinking out loud - could I have a ground problem (G106 maybe). The scan tool is creating the ground between blk/wht and wht/blk at the ADL? That is why the fans run with it inserted?
Only other thing I can is ECM bad.....
Granted I am new and have limited knowledge on this car at this point.
Yes, grounding the ALDL connector causes the ECM to go into diag (fault) mode. In turn, the ECM triggers the fans to run.
My temp guage is digital. Not sure what you mean by "pegged". I posted specific degrees where the fan is triggered!
Thread Starter
Racer
Joined: Aug 2011
Posts: 494
Likes: 138
From: Chesapeake, VA
That was in response to the guy above you with the short one line comment, sorry....
My temp guage is analog - all analog except for speedo/odo (90 was a big change year for interior)
Before I make myself crazy. I am expecting the fan(s) to come on at idle but Is this a normal condition? Start the car (it's cold), let it idle for 15-20 minutes and the temp guage just keeps rising to max hot? and the fans don't come on (These cars actually need airflow?). Oil temp just starting to rise.
My temp guage is analog - all analog except for speedo/odo (90 was a big change year for interior)
Before I make myself crazy. I am expecting the fan(s) to come on at idle but Is this a normal condition? Start the car (it's cold), let it idle for 15-20 minutes and the temp guage just keeps rising to max hot? and the fans don't come on (These cars actually need airflow?). Oil temp just starting to rise.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
That was in response to the guy above you with the short one line comment, sorry....
My temp guage is analog - all analog except for speedo/odo (90 was a big change year for interior)
Before I make myself crazy. I am expecting the fan(s) to come on at idle but Is this a normal condition? Start the car (it's cold), let it idle for 15-20 minutes and the temp guage just keeps rising to max hot? and the fans don't come on (These cars actually need airflow?). Oil temp just starting to rise.
My temp guage is analog - all analog except for speedo/odo (90 was a big change year for interior)
Before I make myself crazy. I am expecting the fan(s) to come on at idle but Is this a normal condition? Start the car (it's cold), let it idle for 15-20 minutes and the temp guage just keeps rising to max hot? and the fans don't come on (These cars actually need airflow?). Oil temp just starting to rise.
Typcially, the impedement to cooling at idle are: incorrect operation of the fans (which you may be experiencing), and an extremely dirty radiator/condenser cavity. To access the later, the radiator shrould must be removed. Then, you'll find all kinds of horrible gunk.
Since I am unfamiliar with the 90 guage, I'll defer comment to your real issue....identifying when the fans should come on in reference to your temp guage. A later year owner will have to jump in and reply.
I will say, again, they're supposed to run with the scan tool attached. Without it, is when they will stay off until 225 is hit.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
After reviewing my 89 FSM, it appears the aux fan should trigger at 228 (not 238) degrees.
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Thread Starter
Racer
Joined: Aug 2011
Posts: 494
Likes: 138
From: Chesapeake, VA
I see there are 4 or 5 cooling fan threads going now.....but i guess I can close mine out.
As I mentioned I just bought this car - it had been sitting for about a year - very grimey and nasty.
today after changing plugs, wires, cap, rotor, pcv, and fuel filter....plus add some fresh gas. I gunked and washed the engine.
I fired her up to burn off the water, etc. and realized after a while the fans were running. Both fans kicked on actually about the same spot I thought I saw the temp gauge getting up to the other day.
Sooooooo.....I will chalk it up to a) no really knowing the car yet. and b) she's excited to receive some much needed attention.
As I mentioned I just bought this car - it had been sitting for about a year - very grimey and nasty.
today after changing plugs, wires, cap, rotor, pcv, and fuel filter....plus add some fresh gas. I gunked and washed the engine.
I fired her up to burn off the water, etc. and realized after a while the fans were running. Both fans kicked on actually about the same spot I thought I saw the temp gauge getting up to the other day.
Sooooooo.....I will chalk it up to a) no really knowing the car yet. and b) she's excited to receive some much needed attention.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
1990 fans are different from 1989 thus the confusion. I'm going to guess you had some kind of grounding issue now that the fans work after washing. They may go again at some time in the future. If they do check for electrical continuity and grounding. BTW a lot of 1990 analog gauges are unreliable.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
just remember, the fans are not there to regulate normal temps, but to reduce high temps to a manageable level once the engine is in the operational temp range.
the normal cycle is:
start and warm up to operating range, if exceeded, fans come on, and engine returns to operating temp range.
Expect to see the temp see-sawing up and down. This is normal.
Also, the fans are turned off above 35 mph.
Expect to see higher temps with the air conditioning off. It is programmed for the one fan to run when the air is selected, below 35 mph, and the other one to come on with it when the temp climbs above operation range.
the normal cycle is:
start and warm up to operating range, if exceeded, fans come on, and engine returns to operating temp range.
Expect to see the temp see-sawing up and down. This is normal.
Also, the fans are turned off above 35 mph.
Expect to see higher temps with the air conditioning off. It is programmed for the one fan to run when the air is selected, below 35 mph, and the other one to come on with it when the temp climbs above operation range.
Last edited by coupeguy2001; Sep 5, 2011 at 11:47 AM.