My engine overheats why?

2003 MERCURY MARQUIS
172,525 MILES • V8 • 2WD • AUTOMATIC
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QUALITYTIRE1
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  • 2 POSTS
Engine overheats only when a/c is on under a load?
Aug 28, 2009 at 7:32 PM
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MERLIN2021
  • CAR REPAIR CONTRIBUTOR
  • 17,250 POSTS
Check/replace thermostat, flush system and refill with Ford approved coolant. 50-50 mix. Inspect radiator cooling fins for clogs, blow out with compressed air. Also, lets go over this guide to help us fix it.

https://www.2carpros.com/articles/engine-overheating-or-running-hot


Please run down this guide and report back.



Aug 28, 2009 at 7:55 PM
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SAVAGE JUICE
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Digital dash blinks out and car runs hot. turn car off then turn ignition on dashboard light comes back on. what can be the problem?
Feb 25, 2021 at 10:53 AM (Merged)
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BMDOUBLE
  • CAR REPAIR CONTRIBUTOR
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As far as the overheating goes, There are several things that could go wrong to cause this. On these cars the most common things that I have had are: 1. Intake leaks at the front left and right corners. 2. water pump weep hole leaking. 3. electric fans failing. 4 head gasket failure. The instrument cluster on these vehicles are known to have bad solder joints. I have repaired these myself by re-heating the solder joints near where the connector goes, but if possible there are computer repair people lately that have made these repairs, because at the end of the day circuit boards are circuit boards! Here is guide that may help with the overheating issue: https://www.2carpros.com/articles/engine-overheating-or-running-hot
Feb 25, 2021 at 10:53 AM (Merged)
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DRGES13
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Car overheated past two days, flushed the system put in new thermostat still overheats. Noticed when car reaches operating temperature the fan stops spinning.
Feb 25, 2021 at 10:53 AM (Merged)
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ASEMASTER6371
  • CAR REPAIR CONTRIBUTOR
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Good morning,

Yes, the cooling fans were an issue with the old Mercury's.

I would replace the fan and module together. That is what controls the operation of the fan.

When the engine first starts, the fan should come on high speed right away and then drop down.

Roy
Feb 25, 2021 at 10:53 AM (Merged)
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