Cooling fan issue - Chevy Impala SS Forum
 
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post #1 of 9 (permalink) Old 03-12-2016, 06:06 PM Thread Starter
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Cooling fan issue Solved

Primary (passenger side) cooling fan is not coming on before the secondary. I disconnected the temp sensor in the water pump and both fans run (which means relays and fuses are good...right?). Both fans run when the a/c is on sometimes(not always). I changed the temp sensor in the water pump today with no change. Secondary comes on under normal driving when stopped at a light or stop and go traffic, primary does not. Primary fan runs when hot wired. I did the mechanical fan delete about 10 years ago with no problems until a few months ago. Car is not overheating but I am concerned the secondary fan will soon wear out when summer heat arrives(Florida heat). What else should I check?

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Custom tune (secret tuner), Homemade RAISS, LT4 knock mod, X-pipe, Dynamax muff dumps in front of rear wheels, Gary's headlight & batt. cable, Mueller bushings, Air lift bags w/aftmkt compressor,
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Last edited by WindSSurfer; 03-30-2016 at 08:57 PM. Reason: solved the issue
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post #2 of 9 (permalink) Old 03-12-2016, 10:33 PM
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re the wires hooked up wrong? That would be the obvious thing.

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post #3 of 9 (permalink) Old 03-13-2016, 08:03 AM Thread Starter
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Originally Posted by fbi9c1 View Post
re the wires hooked up wrong? That would be the obvious thing.
Correct me if I am wrong, but if the fans come on when the Temp Sensor is unplugged, doesn't that rule out incorrect wiring?

94 RMW
Custom tune (secret tuner), Homemade RAISS, LT4 knock mod, X-pipe, Dynamax muff dumps in front of rear wheels, Gary's headlight & batt. cable, Mueller bushings, Air lift bags w/aftmkt compressor,
TB bypass, Tranny cooler w/fan, Air pump delete, Elec. fan cnvrsn, UMI LCAs, HO swaybar, Bilsteins, Vogtlands, ZQ8s, Blazer floor shift cnvrs w/twin buckets, leopard print velvet roofliner
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post #4 of 9 (permalink) Old 03-13-2016, 01:16 PM
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post #5 of 9 (permalink) Old 03-13-2016, 01:32 PM
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Been a while since I looked at the tables but the secondary as also triggered by AC pressure switch if I recall.
Is it possible that the secondary is coming on early , as opposed to the primary coming on late?
Something up with the AC pressure switch?
you could try unplugging it and watch the operation of the two fans as the car heats up idling with the HVAC turned off

What did your secret tuner set the tables to ?


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post #6 of 9 (permalink) Old 03-14-2016, 09:04 PM
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If you connect it to the PC scanner, live data program, may show when the PCM is commanding the fans to turn on? If its good to that point it will rule out the problem. I forget if Datamaster or freescan(is that the name I forget) shows that info. I know a real scan tool will. Did the china AC switch go bad?

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Last edited by ghetto wagon; 03-15-2016 at 03:25 PM.
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post #7 of 9 (permalink) Old 03-15-2016, 09:15 PM Thread Starter
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If you connect it to the PC scanner, live data program, may show when the PCM is commanding the fans to turn on? If its good to that point it will rule out the problem. I forget if Datamaster or freescan(is that the name I forget) shows that info. I know a real scan tool will. Did the china AC switch go bad?
My old XP laptop died the one I use to scan and flash and I am not able to get Freescan to run on my Windows 10 laptop.
I tested everything on the car including the wire from the PCM to the relay. All wires are good, all relays are good, all fuses are good, primary fan runs when hot wired. Definitely sounds like a programming issue. I may have to buy another cheap XP laptop just so I can reflash the PCM. The AC switch seems ok, AC is cold. I will test it this weekend. Gerry suggested unplugging the AC pressure switch to see what happens with the fans.

94 RMW
Custom tune (secret tuner), Homemade RAISS, LT4 knock mod, X-pipe, Dynamax muff dumps in front of rear wheels, Gary's headlight & batt. cable, Mueller bushings, Air lift bags w/aftmkt compressor,
TB bypass, Tranny cooler w/fan, Air pump delete, Elec. fan cnvrsn, UMI LCAs, HO swaybar, Bilsteins, Vogtlands, ZQ8s, Blazer floor shift cnvrs w/twin buckets, leopard print velvet roofliner
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post #8 of 9 (permalink) Old 03-15-2016, 11:50 PM
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I have my trash found Dell XP laptop that works fine, It even re flashes the PCM. If you want to take a look you are more than welcome to. Start looking in the trash for computers, you will find something, Serious!

ya windows 10 blows.

The Low pressure switch which is on the drier should command signal to the passenger side fan as it does to the AC compressor clutch coil ? Maybe I am guessing here. The drivers side fan kicks on when the high side AC pressure is 250psi or higher it uses that switch on the high side that was replaced.

Car still works MOD

Last edited by ghetto wagon; 03-16-2016 at 03:39 PM.
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post #9 of 9 (permalink) Old 03-20-2016, 09:12 PM Thread Starter
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Found the problem

Finally found the problem. When I did the electric fan conversion many years ago, I used a female spade connector for the primary fan's 40 amp fuse in the under hood fuse box. The connector was not locked into the slot inside the fuse box and when I pushed the fuse back in after checking it constantly it would make contact for a while causing the fan to work but after a while the connector moved down and lost contact with the fuse blade thus causing the primary fan to lose power. It always seemed to work right after I checked the fuse causing the confusion. I rerouted the hot wire and fuse out of the fuse box until I can get the correct connector that will lock into the fuse box slot.

94 RMW
Custom tune (secret tuner), Homemade RAISS, LT4 knock mod, X-pipe, Dynamax muff dumps in front of rear wheels, Gary's headlight & batt. cable, Mueller bushings, Air lift bags w/aftmkt compressor,
TB bypass, Tranny cooler w/fan, Air pump delete, Elec. fan cnvrsn, UMI LCAs, HO swaybar, Bilsteins, Vogtlands, ZQ8s, Blazer floor shift cnvrs w/twin buckets, leopard print velvet roofliner
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