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View Full Version : Cooling fan Turns on after shutdown?


Supercomp729l
07-02-2007, 12:41 PM
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PaCemkr86
07-02-2007, 12:54 PM
this is normal operation for the fan delay relay

PhillyTurboSix
07-08-2007, 05:19 PM
If you turn the AC on the fan(s) should come on right away. If the car reaches temps over 200 the delay/relay will kick the fans on till the car cools down below 200. Even if the car is turned off with the key out the fan(s) will run. That's why it's good to make sure you have a 160 stat. On days when it's super hot these cars heat soak really fast and get over 200 in a hurry. You pretty much can't do anything about it other then not running the AC and letting the car cool down between passes as much as possible.

Dixiesys
07-08-2007, 11:41 PM
If you turn the AC on the fan(s) should come on right away. If the car reaches temps over 200 the delay/relay will kick the fans on till the car cools down below 200. Even if the car is turned off with the key out the fan(s) will run. That's why it's good to make sure you have a 160 stat. On days when it's super hot these cars heat soak really fast and get over 200 in a hurry. You pretty much can't do anything about it other then not running the AC and letting the car cool down between passes as much as possible.

Hmm driving around the hot Alabama summer sun, my car ALWAYS runs the fan after shutdown. Sounds like this could be a cause of some concern?

PhillyTurboSix
07-09-2007, 12:03 AM
Well means your car is way over 200 degrees when you shut it off. Personally I don't like my cars to run hot like that. My TTA is all stock and sometimes with the AC on it will run for a 30 secs to a min. But that's a stock T-stat. You want to make sure you have a 160 in there and the radiator is flushed and flowing well. I put under 1000 miles on my GN in a typical season and I flush the radiator twice. The TTA I put under 300 miles a year and flush that at least once. Cooling is always a major issue with these cars. That little V6 heat soaks real fast in the heat and takes a long time to cool back down!

Keller
07-09-2007, 04:19 AM
If your fan delay relay is shot, it will also go on EVERY time you shut down. Does not matter if its 100 degrees outside or -100 degrees outside and you only had your car on for 10 seconds.

Have to check, but that may be another discontinued GM part.

PhillyTurboSix
07-09-2007, 08:05 AM
The only good part is the delay relay is one of those relays that very rarely goes bad on these cars. They are no longer available from GM. Chances are in most cases.. poor cooling system and or 180 stat still in the car.

Dixiesys
07-09-2007, 08:46 PM
If your fan delay relay is shot, it will also go on EVERY time you shut down. Does not matter if its 100 degrees outside or -100 degrees outside and you only had your car on for 10 seconds.

Have to check, but that may be another discontinued GM part.

Hmm ok something I noticed, when I did the paperclip thing to read the codes in the ECM the fan came on, the car had not been ran at all so there's no way it was hot.

Sign of a messed up relay maybe?

Does the scanmaster or powerlogger record coolant temp in the radiator? Or will I need to put a proper sender somewhere to a temp gauge? I got a temp gauge in the closet just need a sender to hook it up to. But if the scanmaster or powerlogger let's me monitor temp then why bother right?

PhillyTurboSix
07-09-2007, 09:36 PM
Scanmaster and Powerlogger will both read the temp for you.

Keller
07-09-2007, 10:08 PM
Hmm ok something I noticed, when I did the paperclip thing to read the codes in the ECM the fan came on, the car had not been ran at all so there's no way it was hot.
That is just the way it works. It is not the sign of a problem.

Keller
07-09-2007, 10:13 PM
But if the scanmaster or powerlogger let's me monitor temp then why bother right?
Chances are slim that you will go down the road with a laptop all the time.

If you have a Scanmaster, it will read it OK. But will you always have it set on coolant temp? And a gauge needle out of place will catch your eye faster.

Just a few thoughts...

PhillyTurboSix
07-10-2007, 07:40 PM
I don't know if it's because of where the Scanmaster or PowerLogger get the temp readings from but I also have a autometer temp gauge in the car with a probe right in the intake and that is always 10 or more degree hotter then what the Scanmaster and or Powerlogger reads. I talked to some other guys with temp gauges and they same the same thing. Anyone else run into this?

jcawley3
07-10-2007, 07:59 PM
reading this thread has got me thinking......mine only come on when the AC is on....even when powerlogger reads over 200 temp which is not often and the highest i've seen it is 204...never heard them after shutdown either...
How can I check this? my relays are very "gummy" when I unpluged them like maybe the inside melted?....

**don't mean to steal the thread...just figured since it was the same problem ...sort of**** thanks

PhillyTurboSix
07-10-2007, 08:06 PM
If you turn the AC on the ECM fires the fan up even if the car is cool. 204 is'nt bad on a stock t stat and or radiator on a hot day. The gummy stuff on the relays is normal. That's to help keep moisture from getting in them. That is usually what happens. They get moisture in them and fail from washing the car or driving in the rain. Kirban actually sells a cover for the driver side relays that works well keeping water off of them.

jcawley3
07-10-2007, 08:19 PM
thanks for the reply....its got the 160 stat in it....this was a 100 degree day...any idea why there not coming on automatic? *when hot

PhillyTurboSix
07-10-2007, 08:34 PM
So your fans never come on unless you have the AC on? Here is how the circuit works. You should be able to track down the issue here.

http://www.gnttype.org/techarea/images/wiring_images/cooling_fan_circuit.jpg

jcawley3
07-10-2007, 08:39 PM
no never.....thanks for the link, but that could be a treasure map to Hidden GNX and I couldn't follow it....

PhillyTurboSix
07-10-2007, 08:53 PM
Well with a meter you can figure most of that out pretty easy but if your lost there you might want to take the car to your local turbo buick repair shop. It could be a number of things.

jcawley3
07-10-2007, 08:55 PM
thanks for the help philly....

Keller
07-11-2007, 01:23 AM
If you turn the AC on the ECM fires the fan up even if the car is cool.
Study the schematic again. The A/C doesn't care about the ECM for engagement of the fan. It hard switches the high speed coolant fan relay on when the A/C is engaged.

There is a good chance the car in question has a bad or missing coolant sensor, or a bad relay. Check the wiring and sensor/relays out.

PhillyTurboSix
07-11-2007, 12:44 PM
Study the schematic again. The A/C doesn't care about the ECM for engagement of the fan. It hard switches the high speed coolant fan relay on when the A/C is engaged.

There is a good chance the car in question has a bad or missing coolant sensor, or a bad relay. Check the wiring and sensor/relays out.

That's what I mean to say. Somehow ECM got in there :doh: Just checking to see if you were paying attention! :innocent: Posting on to many boards at one time! :duh: :brows:

Supercomp729l
07-11-2007, 02:28 PM
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Dixiesys
07-11-2007, 11:56 PM
Thinking I may have a bad relay, went out today, cranked the car ran it 10 seconds at most, got out, fan came on, was on for at least several minutes. Got back in it, later, moved it to the side of the house, fan stayed on again. Got back in later to play with the powerlogger and my laptop, powerlogger said 174F when I shut it off, and yep, fan on when powered down.

kenmosher
07-12-2007, 08:42 AM
Hello,
Fan relay going bad?

Sounds like it's sticking ... it's the "Delay Relay" (and it does just what you described when triggered ... in fact, I have a switch wired to trigger it for cool down at the track).

JCStark
07-24-2007, 05:34 PM
Hi Everyone,

I'm new to this web site, but I joined because I have a TTA and am experiencing cooling problems. I don't want to jump into the middle of this conversation if it is not appropriate to do so (I have never joined one of these sites before, so I don't know all the rules of holding discussions like these), so let me know if I am breaking the rules here, or if I need to start another thread, or whatever.

Anyway, my TTA is having similar cooling problems. The primary fan will only kick on at about 240F (according to TurboLink), and the secondary does not want to kick on at all. I have changed the primary, secondary and fan delay relays. I have a relatively new temp sensor in it. The fan will kick on at around 240F and only stay on for a minute or so, not nearly long enough for it to cool off the motor. I have a 160F thermostat in it.

Two questions: Is the wiring diagram for the GN in this thread the same for the TTA? And, is it possible to set the temp at which the fans kick on (my understanding is, it is set in the PROM somewhere)?

Thanks,

Jim Stark

JCStark
07-24-2007, 05:49 PM
Sounds like it's sticking ... it's the "Delay Relay" (and it does just what you described when triggered ... in fact, I have a switch wired to trigger it for cool down at the track).

Ken,

I was thinking of doing this to my TTA as well, since I can't seem to fix the "fan not coming on" issue. Do you have a wiring diagram? Did you wire in a relay, bypass the factory relays, or just what? Any info you can share would be appreciated.

Thanks,

Jim Stark

kenmosher
07-25-2007, 09:34 AM
Wiring details are on the site in the Electrical section:

http://www.gnttype.org/techarea/electrical/switches.html

Pretty much you just ground one of the wires on the delay relay.

As far as the TTA ... the wiring is very similar, but the TRs don't have dual fans ...

JCStark
07-25-2007, 11:33 AM
Wiring details are on the site in the Electrical section:

http://www.gnttype.org/techarea/electrical/switches.html

Pretty much you just ground one of the wires on the delay relay.

As far as the TTA ... the wiring is very similar, but the TRs don't have dual fans ...

Ken,

Thank you very much! Seems simple enough. Naturally, I would rather have the ECM kick the fans on, but if I can't figure out why it is not, this will keep me from overheating.

Any clue as to why my fan would be kicking on at 240F? Is there a way to program the PROM to make it come on at the right temp?

Thanks for all your help.

Jim Stark

Keller
07-25-2007, 11:36 PM
Yes...but not if there is an electrical problem.

JCStark
07-26-2007, 10:43 AM
I am not sure what more I need to check regarding the electrical. I've replaced the primary and secondary fan relays, and the delay relay. If I short out the right post on the relay, I can get the fans to turn on. If I plug in TurboLink, it shows the primary fan kicking on at around 240F. It will run for a minute or so, and shut off.

Any clue as to what else I should do? Any suggestions are appreciated.

Thanks,

Jim