Chevy Cobalt Forum banner

Status
Not open for further replies.
1 - 10 of 10 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter #1
I have a 2005 Chevy cobalt. I purchased the car with low mileage on it and like to think I properly maintained it through out the years. At this point how ever im not happy with my little blue friend.

I have gone to multiple mechanics, including 2 gmc dealerships.

here is my 2 year long story.

My car over heats. not always, it really is weather pending. on warm days, it takes sometimes less then 15 mins to get it self up to 100 degrees. My car has always hovered around 87-89 degree range, sometimes, up to 90. by 105-106, it stalls.

There is no dash lights indicating anything. I have no coolant leaks or low on coolant, thermostat is working as it should, rad is working fine. I have no problems with my heat, I have no problems with my AC either. In the winter time, the car runs perfect, never getting hot.

I have one mechanic, ( not gm) thinking that it may be the computer. Something about the relay is not receiving a signal from the computer to turn the fan on. This to me makes sense to a certain degree, how ever, this is the ONLY issue with the car, it over heats. He pulled the slow speed relay out for the fan to keep the fan for the motor running all the time, and the car ran like a charm, no issues what so ever! But I clearly cannot drive around for the rest of my cars years like this.

I have a second mechanic telling me that its the battery.....

Gm is telling me that its the water pump and want me to pay almost 600.00 to fix it. This to me does not make sense and I have heat, I have air conditioner in my car, and for what ever reason, when I turn on my AC, the compressor turns the fan on bringing the car back down to its normal temperature.

I have no idea what to think here. I know I should be taking GMC dealership advice seeing as they made the car but for someone who has with a previous car replaced a water pump, doesn't seem like that could be the issue.

The second GMC dealership told me its nothing and its ok for the car to get hot like that. (someone clearly has no mechanical skills and should not be working at a dealership)

Im not sure what else to do, or how to go about finding out the issue with the car. I have spent so much money trying to figure out whats going on that im almost at a situation where I don't want to, im ready to walk away and get my self a pretty Elantra! Has anyone else had this issue? or know what the problem might be? any type of insight would be amazing! Thank you in advance.
 

·
Super Moderator
Joined
·
11,821 Posts
I think I know what your problem is. Do you live in the southern states?
 

·
Super Moderator
Joined
·
11,821 Posts
Okay then I believe somebody added pure water to your coolant at some point. Coolant works best at 50-50 mixture of Dexcool and distilled water. If your coolant is 30-70 it will still work somewhat but won't tranfer heat through the radiator fins as well as proper 50-50 Coolant. Have you ever had your system flushed and replaced by Dexcool?

By the way Fan 1 speed is only commanded at 106°C so at 100 you're still within norms.

The ECM commands Low Speed Fans ON under the following conditions:

• Engine coolant temperature (ECT) exceeds approximately 106°C (223°F).

• A/C refrigerant pressure exceeds 1 310 kPa (190 psi).

• After the vehicle is shut off, the ECT at key-off 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 ECM commands High Speed Fans ON under the following conditions:

• ECT reaches 110°C (230°F).

• A/C refrigerant pressure exceeds 1 655 kPa (240 psi).

• When certain DTCs set

When the request for fan activation is withdrawn, the fan may not turn OFF until the ignition switch is moved to the OFF position or the vehicle speed exceeds approximately 10 mph. This is to prevent a fan from cycling ON and OFF excessively at idle.
 

·
Super Moderator
Joined
·
11,821 Posts
If you don't have a TechII, let your car idle and watch the temperature monitor, it should turn fan one at approxamitely 106°C if at 110°C it hasn't come on you have an ECM issue.

If you have a TechII you can command the ECM to turn on fan 1 or fan 2. Then you will know that your ECM is good.

Do you know if your coolant is 50-50?
 

·
Registered
Joined
·
5 Posts
Discussion Starter #7
im not sure. I haven't had the rad flushed in about 3 years maybe 4. ( I am the person who pays the garage to replace my lights lol) up until this issue, the only thing I knew about cars is how to drive them and when they make funny noises bring it to the garage.... how do I know if I have a TechII? Would the ECM effect anything else other then just the fan?
 

·
Super Moderator
Joined
·
11,821 Posts
I still think your Dexcool has been diluted, and the symptoms you're talking about is typical of quick up temperatures and wierd responses from the system to try and correct what it reads.

---------- Post added at 09:48 PM ---------- Previous post was at 09:45 PM ----------

TechII is the GM scan tool used to diagnose these problems.

 

·
Registered
Joined
·
5 Posts
Discussion Starter #9
Im going to bring it in an have the coolant changed out. Seems like the cheaper option at this point. Thank you! Ill let you know how it goes.
 

·
Levee
Joined
·
3,210 Posts
It hasn't been answered yet, but your fan turns on with the AC because it needs to be on. The fan pushes air through the AC condensor (radiator in front of your coolant radiator) to help cool down the refrigerant oil in your Ac system.

If you fan works when the relay is removed, the fan is fine and your coolant temp sensor is bad, Relay is bad or ecm is bad. Just some insight.
 
1 - 10 of 10 Posts
Status
Not open for further replies.
Top