When I stop my MCS 2007 the fan comes on VERY LOUD. I had to check if the car had actually stopped. Was having a low hum at first (two months ago), then had the thermostat replaced, mechanic said it's ok to have a low hum as the car gets older. Then noticed losing coolant. Found out I had a small water pump leak. Did nothing but kept the coolant tank filled to almost top all the time. Now, for past week, in spite of the coolant reservoir being almost full, after I've driven the car say about 10 min and then stop it, the fan remains running full on. Does the fan run fast and therefore louder when the car is overheating? And why would it be overheating if the coolant reservoir is full? Thank you!

 

 

When u run the A?C or its hot outside and the car ran hard to sat in traffic for a long time it will kick on the high speed fan.

 

Bad Coolant Temp Switch would make the fans run all the time

 

Thank you. I will be taking this in to my mechanic. I do not have a scan gauge. This problem is now complicated by the fact that the problem disappeared in the last two days (i.e., the fan is not coming on). Even so, the worry is there that the car is overheating anyway. I will update this post when I get the definitive answer (and fix) from my mechanic.

 

Will have mechanic check for a bad coolant temp switch and post his diagnosis and fix here. Thank you!

 

What he said!

 

I will do that. I will take to the local mechanic to check the switch. Thank you.

 

Will not take to my mechanic for this issue. He wants to replace the thermostat ($900) and what if it's the water pump leak ($3,000 est)? The code is 2F07. 2F07 "Map thermostat. Possible water pump" I will have the local mechanic check the coolant temp switch, and update this thread with results.

 

Took your suggestion to mechanic; he checked and car is not overheating. Temp is 103 deg F. So next step is to see if it's the Coolant Temp Switch. Will update here and elsewhere what the cause was. Thank you for your suggestion, very helpful!

 

Jeebus. Find a new mechanic! Better yet, try to fix it yourself. Man, that's robbery! Did he really quote you $900 to replace a t-stat? Does this dude drive a new 2018 diesel lifted truck? LOL

 

The mechanic’s findings.
Codes:
2F07 Map Thermostat Mechanism
2F22 Engine Temperature
2885 Charge Air Pressure 2F1A Coolant Temperature Signal
Their Notes: Thermostat on warranty; will replace. Water pump leaking causing erratic signals to computer. Check Engine light is set for over heating. It causes fan to run for 15 min after shut down. All sensors are working properly at this point.
My note: Because the check engine light is on on account of the leak in the water pump, the default mechanism is to start the fan when car stops because it thinks the car is running hot when it isn’t.

 

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The mechanic charged $787 for replacing thermostat.My original mechanic wants $900 for same job. I was wrong about the water pump costing, $3,000. It would be $1,040.