Weird fan behavior
04-30-2019, 11:31 AM
#1
Weird fan behavior Hello guy's so I have a 95 trans am that I just purchased like a month ina half ago with only 28xxx miles on the new motor with a rebuild tranny. Reason i say new is because the previous owner swapped the original motor with another lt1 block from a 96-97 modal. While under the car one day I spotted a cps, but wasn't plugged up cause the pcm is a 95 so it doesn't even know what a cps is. But that not the issue, it's the fans which got me confused. When I got it I noticed everytime I started it, fans will come on right away. Even when I turn the key to the On position, fans kick on. No ses light is on and that was weird cause they will stay on the whole time Im driving until I shut it off. Also I noticed the ses will come on every now and then when I start it and will not come on other starts. So I started replacing parts like the maf, o2s, map, iat, spark plugs and wires, ect, idler valve on throttle body. Hell I even replace the gauge sensor on driver head. Fuses everything I can fix that ses. So after all that, light doesn't come on anymore. But fan still run and now it's only one (Passenger side fan) and the driver side fan doesn't work, even when I turn the ac on still doesn't. It's only comes when I pull a sensor and ses light comes on then both fans are blowing high speed. But when I plug it back in driver fan goes back off and passager fan just keeps blowing. I did notice a switch inside the car but it doesn't even work. I need some help on figuring this fan problem out. Car sometime reach 245 degrees and driver fan still doesn't come on. Only when I pull a sensor it works. Any info help thanks
04-30-2019, 03:52 PM
#2
TECH Regular
Try posting in one sub-forum instead of spamming this place.
Instead of throwing parts at it, maybe plug the car in and see what it is trying to tell you. Do a search for scanning options - almost all are free. The check-engine light means a code is thrown, and stored. Pull the code and fix the problem.
Instead of throwing parts at it, maybe plug the car in and see what it is trying to tell you. Do a search for scanning options - almost all are free. The check-engine light means a code is thrown, and stored. Pull the code and fix the problem.
04-30-2019, 04:21 PM
#3
Try posting in one sub-forum instead of spamming this place.
Instead of throwing parts at it, maybe plug the car in and see what it is trying to tell you. Do a search for scanning options - almost all are free. The check-engine light means a code is thrown, and stored. Pull the code and fix the problem.
Instead of throwing parts at it, maybe plug the car in and see what it is trying to tell you. Do a search for scanning options - almost all are free. The check-engine light means a code is thrown, and stored. Pull the code and fix the problem.
04-30-2019, 04:29 PM
#4
TECH Regular
Do a search for scanning options - almost all are free.
04-30-2019, 09:59 PM
#5
As of right now I don't got any pc to use it. There was a gm innoval brand scanner I was going to get off of summit racing. It comes with a adapter to scan OBD1 and 2.
05-01-2019, 06:10 AM
#6
TECH Veteran
Don't get an Innova scanner. Some models are notorious for giving out false info for LT1s. I'd concentrate on making sure the factory wiring for the fans was intact. The switch you mentioned could be a suspect, though you say it does not work. Unless you investigate, you don't know what wiring has been altered.
05-01-2019, 10:55 AM
#7
Don't get an Innova scanner. Some models are notorious for giving out false info for LT1s. I'd concentrate on making sure the factory wiring for the fans was intact. The switch you mentioned could be a suspect, though you say it does not work. Unless you investigate, you don't know what wiring has been altered.
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05-01-2019, 11:30 AM
#8
TECH Regular
The fans kick on when the CEL comes on (from certain codes) as a precaution against overheating due to whatever fault is tripping the light. You can continue to throw parts at the car until you hit whatever issue is causing the CEL, but I'd pull the codes instead. It's cheaper. Even if you have to purchase a $100 laptop off of Craigslist and a $50 cable. Plus, you'll have the proper tools to diagnose issues moving forward.
05-01-2019, 02:48 PM
#9
The fans kick on when the CEL comes on (from certain codes) as a precaution against overheating due to whatever fault is tripping the light. You can continue to throw parts at the car until you hit whatever issue is causing the CEL, but I'd pull the codes instead. It's cheaper. Even if you have to purchase a $100 laptop off of Craigslist and a $50 cable. Plus, you'll have the proper tools to diagnose issues moving forward.
05-01-2019, 03:43 PM
#10
TECH Regular
So is it possible for the pcm somehow bypass a dead fan to work when the ses is present? I know that when the ses comes on the fan kick on. But when I reach high temp or turn on ac it doesn't come on. Which makes me think it's a dead fan? Like I stated above fans were both working continuously when I got the car without a check engine light. What's a good scanner for the OBD1 system?
05-01-2019, 08:06 PM
#11
05-03-2019, 01:33 AM
#12
So here the updates guys, I got my car finelly scanned and turns out my air pump is going. Makes sense cause whenever I cold start ses light comes on and that's around the time air pump is active , but warm starts light doesn't come on. It Still doesn't explain why my fan ain't operating normally like it should.
05-03-2019, 12:38 PM
#13
Post No 7 states you have three fan relays.
Your fans should always operate simultaneously wether in low speed (series connection) or high speed (paralell cnnection)
Test both fans by supplying 12V directly to the fan motor terminals to determine if the problem is a dead fan or bad wiring to the fan that does not operate.
Your fans should always operate simultaneously wether in low speed (series connection) or high speed (paralell cnnection)
Test both fans by supplying 12V directly to the fan motor terminals to determine if the problem is a dead fan or bad wiring to the fan that does not operate.
05-19-2019, 09:52 PM
#15
Post No 7 states you have three fan relays.
Your fans should always operate simultaneously wether in low speed (series connection) or high speed (paralell cnnection)
Test both fans by supplying 12V directly to the fan motor terminals to determine if the problem is a dead fan or bad wiring to the fan that does not operate.
Your fans should always operate simultaneously wether in low speed (series connection) or high speed (paralell cnnection)
Test both fans by supplying 12V directly to the fan motor terminals to determine if the problem is a dead fan or bad wiring to the fan that does not operate.
05-19-2019, 10:13 PM
#17
I am suspicious about that switch inside the car, and that it maybe the reason both fan was on at all time in the first place. Even thought the switch didn't work, it might be the cause. Regardless something is off and im just stamped right now and I don't know where to look at now.
05-20-2019, 09:11 AM
#18
Village Troll 
iTrader: (2)
Like a toggle switch? Even if it doesn't work it could still be passing current. Have you tried unplugging said switch? You can also get a volt meter and do some poking around the switch to see if it is a closed circuit/passing current. You should also check around where this switch is to see if there is any hodgepodge bro wiring that's been done. Take the PCM out of its cradle and see if there are any wires attached that don't belong.
You have already been told you need to find out what the codes are. You are going to have to do the digging into this electrical issue yourself unless you want to pay someone to figure it out for you.
You have already been told you need to find out what the codes are. You are going to have to do the digging into this electrical issue yourself unless you want to pay someone to figure it out for you.
05-20-2019, 03:40 PM
#19
Like a toggle switch? Even if it doesn't work it could still be passing current. Have you tried unplugging said switch? You can also get a volt meter and do some poking around the switch to see if it is a closed circuit/passing current. You should also check around where this switch is to see if there is any hodgepodge bro wiring that's been done. Take the PCM out of its cradle and see if there are any wires attached that don't belong.
You have already been told you need to find out what the codes are. You are going to have to do the digging into this electrical issue yourself unless you want to pay someone to figure it out for you.
You have already been told you need to find out what the codes are. You are going to have to do the digging into this electrical issue yourself unless you want to pay someone to figure it out for you.
05-20-2019, 03:45 PM
#20
Like a toggle switch? Even if it doesn't work it could still be passing current. Have you tried unplugging said switch? You can also get a volt meter and do some poking around the switch to see if it is a closed circuit/passing current. You should also check around where this switch is to see if there is any hodgepodge bro wiring that's been done. Take the PCM out of its cradle and see if there are any wires attached that don't belong.
You have already been told you need to find out what the codes are. You are going to have to do the digging into this electrical issue yourself unless you want to pay someone to figure it out for you.
You have already been told you need to find out what the codes are. You are going to have to do the digging into this electrical issue yourself unless you want to pay someone to figure it out for you.