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Hi ETCG fans,
I’m working on an 05 Chevy Impala with the 3.8L V6.
The complaint is that the car will maintain a normal operating temperature in the cooler mornings and evenings. During the day, however, when ambient temperatures are 100F+, the car overheats, and the a/c stops blowing cold.
I’ve been able to ascertain that this is a problem with the cooling fans. When the car reaches operating temp, both fans activate at low speed. If the A/C is turned on, one fan switches to high speed, the other turns off. This fan stays off, even when water temps are near max. So, the radiator is only being cooled by one fan, instead of two.
I’m having trouble making heads or tails with the information available regarding the operation of these fans, but it seems logical that they would both be operating at high speed if coolant temps or refrigerant press reached a certain threshold. Is this correct?
The car doesn’t have any DTC’s, and I haven’t been able to scan and watch ECT yet. I don’t think the fans are faulty, Perhaps one of the three fan relays? BCM?
Where do I go from here?Thanks!
Stay Dirty
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is the car overheating in traffic or parked idling or weather driving or not? at what point is the temp gauge before you see a over heat?
if the cooling fans are the issue you should notice the car over heats when parked and idling, the job of the cooling fans is too push air flow through the radiator, this is otherwise the job of the forward motion of the car, when the car is moving fast enough the fans don’t need to do this work because air moving around and through the engine bay keeps the radiators cool enough to do there job.
radiator fan malfunction is not a common issue with W body 3800 cars, i have personally never seen them malfunction and i will be honest but i have noticed when i turn my AC on both fans kick on my car, and it is almost the same engine and uni body construction, if the car only over heates when parked then i would do further investiagiton into the fans, otherwise i would follow these references 🙂
http://www.ericthecarguy.com/faq/what-to-do-when-your-engine-overheats
hope this helps, keep us posted and don’t be afraid too ask questions.
Low speed fan:
Both fan motors ‘share’ power; voltage drop between loads in a series circuit:[b]
High speed fan:[/b]
Both fan motors are isolated and receive direct 12 volt power:looks like what you are experiencing is normal operation if ratchet faces diagrams are correct, now if your car is over heating you should see the temp gauge heading towards the 3/4 point, a little over and a little under the half way point is normal operation.
[URL=http://s49.photobucket.com/user/13aceofspades13/media/tempgauge.jpg.html][IMG]http://i49.photobucket.com/albums/f261/13aceofspades13/tempgauge.jpg[/IMG][/URL]
Wow, fantastic
The car overheats in city traffic when the ambient temps are high. I’m in the Phoenix AZ area, it was 116 yesterday. However the car was fine in the evening, idling, with the A/C on. Also this is my neighbor’s car so I don’t have complete access to it.
I’m going to go scan the ECT. From what I read the primary fan turns on at 225F, and the secondary at 232F. Hopefully that will shed some light on where to go next
From the diagram that Ratchet Face posted:
You have two low speeds fans so relay one is working
You have one fan that runs on high speed so relay 2 is working.
Relay 3 must activate to bring on the second high speed fan.
Indeed, Relay #3 was an aftermarket part that had failed. A new relay is in place, and I was able to verify that the problem has been fixed.
Thanks for your help, everyone!
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