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Old 05-04-2006, 09:49 AM   #1
brim
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radiator fan not coming on automatically

I've been toying with this one since last year and still can't put my finger on it.

I changed the coolant temp sensor when I replaced the thermostat, was still having problems then even. I replaced the relay for cooling fan 1 today, and I believe I had done cooling fan 2 last year.

Still with the car sitting, the temp gauge will creep its way up to the third tick mark with no fans. Of course turning on the blower will turn them both on, or turning the AC on will trigger it.

Has anyone else had this problem, I can't seem to find a thread on it so I figured I'd ask.

With no fan switch, temp switch, I'm out of ideas.
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Old 05-04-2006, 10:10 AM   #2
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Same problem here, the relays work, they have power but the PCM doesn't command them to go on. When we hooked up the tech II it showed all signs normal even when getting up to the 230* mark, so I am guessing the board in the PCM is starting to die.

I put in the capsers fan switch and they come on fine with that and fine with the AC on, but never on their own. I am going to try a new PCM but I have to up my custom DHP file into it. Not sure when I will be able to get this done.....

Don't worry man, same problem here, you don't notice it in the winter since they never get that hot, but this time of the year it take no time to really crank up there in temp.
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Old 05-04-2006, 10:29 AM   #3
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it's got me stumped, and as you said, this time of year is where it counts. Although I used to do more traveling till recently, there was nothing like sitting in an hour of traffic with the blower running to keep the temp down
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Old 05-04-2006, 10:41 AM   #4
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Yea, I just picked this up so I can keep the a/c off and that.
Fan Switch Its a temporary solution, but its cheaper and works.
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Old 05-04-2006, 10:46 AM   #5
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Same problem here, ive had this problem forever.
So i said F-it and bought the caspers fan switch.
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Old 05-04-2006, 11:19 AM   #6
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Exact same problem here. I've even had the tank boil over while driving but it was only 3 ticks over 200. Fan turns on when A/C is turned on and cools it down to 200 in no time.

I'm going to replace my thermostat just to make sure it isn't sticking. I think the issue may be that the cooling system in our cars is marginal when brand new but as gunk builds in the radiator, the efficiency goes down. Coupled with the high setpoint of 230 when the PCM engages the fan relays and you have cooling problems.
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Old 05-04-2006, 11:26 AM   #7
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Maybe it's built in obselence?

Mine still manages to keep the car cool. But I've had the coolant flushed. A good bit of gunk built up on the cap, so I replaced it in case it wasn't holding the seal. I'm just hoping the gunk isn't from oil. Ya know where that one goes...

EDIT: I just thought of something, if your tank is boiling over at a few ticks above 200 then your cap is not holding pressure either. Pressure raises the boiling point for liquids...
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Old 05-04-2006, 11:26 AM   #8
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Ive always wondered why these cars run so damn hot.
I have owned 7 cars in my 24 years. This is the ONLY one that gets way to hot for comfort just by idleing.
My truck for instance, i can let that lumber wagon idle in a 100 degree day and the temp wont budge over 180 no matter what. Yet my GA i let it idle on a 60 degree day and within 10 minutes the temp is touching 230 and still rising!!!
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Old 05-04-2006, 06:55 PM   #9
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Quote:
Originally Posted by coupe
Ive always wondered why these cars run so damn hot.
I have owned 7 cars in my 24 years. This is the ONLY one that gets way to hot for comfort just by idleing.
My truck for instance, i can let that lumber wagon idle in a 100 degree day and the temp wont budge over 180 no matter what. Yet my GA i let it idle on a 60 degree day and within 10 minutes the temp is touching 230 and still rising!!!
How are you guys hitting 110°C/230°F ?

I have never seen my car engine coolant temp gauge hit 110°C/230°F (half way between 90°C/194°F & 130°C/266°F) !


Like today it was 22°C/72°F & 33% humidity outside; & my car was sitting parked in the sun all day.
30-minutes driving home on the highway with rush-hour traffic: my car stayed mostly at 86°C/186°F (1-click below 90°C/194°F).
Until the end of the trip it was at 90°C/194°F & climbed, once off of the highway.
I let it idle in the driveway (testing the coolant system - just got a new water pump put in) up to about 100°C/212°F (3-clicks past 90°C/194°F).
At 100°C/212°F: the fan came on low & reduced the temp to just above 90°C/194°F.

I have never seen it hit 110°C/230°F (half way between 90°C/194°F & 130°C/266°F)

It sits normally for me, like 1-click below 90°C/194°F; until I get caught up in traffic or after coming off the highway.
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Old 05-04-2006, 07:08 PM   #10
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It gets that high because the PCM isn't telling the fans to come on, they work and have power, they just don't turn on by the PCM's command. So I think its the board in the PCM thats faulty, just making sure it wasn't my lack of IAT sensor (dhp adjustable timing feature), but it makes me feal better to hear that stock cars are doing the same thing.
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Old 05-04-2006, 08:02 PM   #11
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I noticed my radiator fan seems to cycle on and off intermittently when the weather is hot. It never did this before. Could this mean a new PCM is in order? If so, how much does it cost?

Also, I recently noticed a strong smell like burning electronics coming from inside my car. Of course, it could just be outside air pollution. Anyone else get this? I'm worried it might mean fried PCM.
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Old 05-04-2006, 09:08 PM   #12
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Quote:
Originally Posted by Tony
I noticed my radiator fan seems to cycle on and off intermittently when the weather is hot. It never did this before. Could this mean a new PCM is in order? If so, how much does it cost?

Also, I recently noticed a strong smell like burning electronics coming from inside my car. Of course, it could just be outside air pollution. Anyone else get this? I'm worried it might mean fried PCM.
They cycle on and off because your coolant temp will get to a point to where your high speed fans will cycle on, once it cools down enough it will switch to just the low speed fan. For burning electronics smell, check the wires in your engine bay to make sure nothing is getting too hot.
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Old 05-04-2006, 09:39 PM   #13
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The PCM commands Low Speed Fans ON under the following conditions:

The engine coolant temperature exceeds approximately 106°C (223°F).
The A/C refrigerant pressure exceeds 1310 kPa (190 psi).
The vehicle is shut off when the engine coolant temperature is greater than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay ON for approximately 3 minutes.


The PCM commands High Speed Fans on under the following conditions:

The engine coolant temperature reaches 110°C (230°F).
The A/C refrigerant pressure exceeds 1655 kPa (240 psi).
When certain DTCs set.
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Old 05-05-2006, 05:21 AM   #14
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^^ That sucks becuase mine dosent do that. It didnt even do that when it was 100% stock. Thats why CFS was at the top of my mod list....one of my first mods actually.
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Old 05-05-2006, 10:59 AM   #15
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mine used to come on at the DHP settings, but one day (not sure, it was winter and fans really don't get used then anyways) when it started to get warm again, it got up to 240* and no fans came on at all.
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Old 05-05-2006, 01:36 PM   #16
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Mine used to never get more than 1 tick over 200 degrees as well but with age, the cooling system doesn't seem to work as well.

Mine eventually starts boiling coolant out even though it hasn't reached the temperature where the PCM turns the fans on. Maybe I have an incorrect coolant mixture or the system isn't being pressurized. I've replaced the cap and I'm quite certain I don't have a LIM or head gasket leak. I suppose the temperature sensor could be faulty but that is highly unlikely.

I think that GM put the temperature setpoint for the fans to kick on too high because over time the cooling system becomes more inefficient due to build up in system.
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Old 05-05-2006, 01:39 PM   #17
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I have an idea, do any of you have a lot of bent fins on the A/C condenser? Mine seems to have a lot near the bottom due to years of debris hitting it. The condenser sits in front of the radiator so maybe the reduced airflow is bad enough to be causing this problem?

Anyone ever try straightening the fins?
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Old 05-06-2006, 01:48 PM   #18
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Coupe and HO driver.. that sucks. I know that a code will be thrown if the fans are on when they shouldn't be, you think the other way around would happen .. I've never seen my car above 215.... maybe time for a coolant system flush?
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Old 05-07-2006, 09:18 PM   #19
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I know what you mean, i just had the radiator hoses, and fluid flushed and changed..like 3 days ago, now i gotta check engine light and the Radiotor light is on, is this as well from a faulty thermostat? or PCM??
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Old 05-08-2006, 05:57 AM   #20
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Quote:
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Coupe and HO driver.. that sucks. I know that a code will be thrown if the fans are on when they shouldn't be, you think the other way around would happen .. I've never seen my car above 215.... maybe time for a coolant system flush?
I have had many coolant flushes, they didnt make any difference.
Im really not worried about it, i would be though if i didnt have CFS.
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