Cooling fan's..

[johnl]

My 97 C5 started running a little warm today. I couldn't hear the fan's.
For the last few weeks my Water Temp would rise a little and then go back down on long runs, (maybe 4 to 8 deg's). Normally in the cool morning air on the way to work the temp stay's mid 170's to low 180's.
In the afternoons and evenings it generally stayed in the low 180's untill I got down on surface streets. It would go up to about 200 or so.
Lately in the afternoon the temp would go to close to 220 then eventually go back down to mid 180's.
Today it went to about 225 and stayed there untill I got on the freeway. Back douwn to 214.
I think I have a fan problem. Any ideas?
For a little history I have in the last 6 weeks or so replaced the serpintine belt, the plugs, the plug wires,Oil and oil filter, fuel filter, and the H-pipe (Cats).
I cleared all the codes and ran for a week with no problems.
Here's whats in the DTC:
10-PCM
General Motors P1571 TCS PWM Circuit No Frequency
40-BCM
General Motors B2723 Pass Key Detection Circuit Short To Voltage Or Open
80-Radio
General Motors U1016 Loss of PCM Communications
A0-LDCM
General Motors U1064 Loss of Communication with BCM
A1-RDCM
General Motors U1064 Loss of Communication with BCM

I'm not too worried about the P1571 as the sensors may have been a little clogged. (I went 40,000+ miles with bad cats)

I was hoping Mr. C4C5 might enlighten me with his thoughts.
These are all History codes.

 

[c4c5specialist]

Hi there,
Your 1571 is normal for the 97 model year, as long as it is always history.
Your B2723 could indicate a problem with the ignition key or lock cylinder, however, would not have any effect on the engine running
As for the rest of the codes, they would be considered a byproduct of the communications systems, and would be disregarded.
As far as your running, sometimes, when converters are changed, you will change the way the engine builds up heat.
It is rare, but it does happen.
Honestly, your temperature would still be considered normal.
However, is the front radiator area cleaned consistantly of debris????
As long as you are not going above 230, I would really not worry about it.
Allthebest, c4c5

 

[johnl]

Thanks for your thoughts.That's what I was thinking, a few miscommunications is no biggie.
I am a little concerned about the fans though. Since they are on independent circuits I don’t think they would both go bad at once. I know when the second one comes on you can hear it from the next block. But I don’t remember ever hearing the first one.
I’ll look into them a little more closely and try to determine if one or both are not coming on.

 

[johnl]

I checked ths morning and when the car was up to temp I let it sit there idling. Both fans were running on low. When the temp reading reached 190 both fans went to hi speed. The gauge dropped to 185 or so and the fans went back to low speed. (This is with the A/C on). I was under the impression that when the A/C is on both fans should go to high and stay there.
??

 

[c4c5specialist]

Hi there,
Your fan system is running perfectly.
The low setting for the fans when the AC is on, is correct.
Both fans run at the same speed, being low, med, or high.
I do not think you have an issue with your car.
Allthebest, c4c5

 

[johnl]

Comming from you, thats it, I'm satisfied.
Thanks for thinking about it with me. I guess I sort of get spoiled with the really cool mornings out her durring the winter months.
Summers here now.....whew...Reminds me of Houston.

 

[johnl]

Nope, something is broke.
This afternoon on the same round trip, durring the streets part of the drive it got up to 232 and stayed there, I got onto the freeway and it went down to 214. I think this is from the air blowing the hot air out from the engine carmpartment. This is way too hot for this time of year and the driving conditions I was under. The engine is not talking to the raidiator. Thermostat and or water pump I suppose. Thermostat is the cheapest and quickest. I'll try that first.

 

[tred95]

I know we are not talking apples to apples but I was having high temps on my LT1. This past winter I took the time to take out the radiator and clean it. Made a big difference...still runs up to 230 if I sit and idle but recovers a lot quicker when the fans kick in or when I get on the open road.
I even found an empty oreo cookie package up in the corner pasted against against the air conditioner condenser...and a lot of leaves and other debris.

Pete

 

[johnl]

OK,
I replaced the t-stat and went for a little spin. I did some upper RPM mountain cimbing and the temp never got above 198. I drove aroung the streets while then and never got above 185. But it is cooler out now.
I'll watch it tomorrow on my commute, the drive home will tell.
J

 

[johnl]

Well, to finally put this thread to rest. Today on the commute it stayed in the low170's on the freeway, morning and afternoon. It got to low to mid 190's on the streets.

The "case of the failing thermostat" is now officially closed.
(120,000 miles’ not too bad for an aftermarket T-stat)
Thanks for all the input and interest.