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2010 DTS base trim
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4 Posts
Discussion Starter #1
My 2010 DTS is getting hot at idle only after it has been running a while. I'm pretty sure the thermostat is open, since the engine has already been warm for a while. I do not suspect a problem with the belt as it is tight and looks very new. The temperature goes down as the car gets moving and it gets air flow, so I suspect one or both fans may not be turning on. The problem is intermittent and will reset itself when I pull over and shut off the engine for a few minutes. When it starts back up, the temp goes down fast. Every time it has happened, the A/C has been running and I turn it off immediately while looking for a place to pull over. Turning it back on and off does not kick the fans back on, but letting the car cool down a bit while off, then turning it back on seems to do the trick. This leads me to suspect a sticky or weak fan relay.

The Cadillac dealer had the car for two days and could not re-create the problem. I ordered relays and a Haynes manual, but want to get an idea of where to go with this before they arrive.

Can someone please direct me to the location of the fan relays?

Also, if there are connectors that may need to be checked and re-seated, where would they be located?

Thank you.
 

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2005 CTS/ 2008 DTS/ 2008 STS V8 N*/ 2011 CTS4 ALL W/D Pearl
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688 Posts
Make sure the coolant level is at the full cold arrow about 1 inch below the black top. The 2006-2011 for some reason runs hot if they are down even a little coolant?

Always check coolant level cold 2-4 hours after shut off at least.
 

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2010 DTS base trim
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4 Posts
Discussion Starter #5
Make sure the coolant level is at the full cold arrow about 1 inch below the black top. The 2006-2011 for some reason runs hot if they are down even a little coolant?

Always check coolant level cold 2-4 hours after shut off at least.
It was a little low so I topped it off. The relays that I got from Autozone were all wrong, so I pulled the existing ones out and gave them a "love tap", which I have found to work sometimes with relays by knocking off a carbon deposit... or they break completely and the intermittent problem is solved. After topping it off and re-seating the relays I ran the car in the driveway with AC on in the sun. Both fans are running and the temp stays at the mid line. The problem may not be fixed, so I ordered a complete fuse box with all the fuses in relays in it (brand new) and that should be here in a few days. Once again, the local parts stores let me down. More often than not, they sell me entirely the wrong parts and waste my time and gas.

Thanks for all your help!
 

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No more Cadillacs
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680 Posts
Make sure the coolant level is at the full cold arrow about 1 inch below the black top. The 2006-2011 for some reason runs hot if they are down even a little coolant?

Always check coolant level cold 2-4 hours after shut off at least.
I can tell you that from experience, this is true. Even slightly low seems to cause running hot. I think it allows air to get into the system. The tank is not elevated high enough, like on the 2000-05 Devilles.
 

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1997 Professional Chassis Raised Roof Presidential Limousine
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411 Posts
After topping it off and re-seating the relays I ran the car in the driveway with AC on in the sun. Both fans are running and the temp stays at the mid line.
Pretty sure the fans run automatically when the A/C is on so that might not be an accurate test. What do you consider overheating on the gauge?
 

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Pretty sure the fans run automatically when the A/C is on so that might not be an accurate test. What do you consider overheating on the gauge?
Fans do not always run with the ac selected on DTS models, changed in 2006.
 
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