{"id":34868,"date":"2022-03-10T14:19:34","date_gmt":"2022-03-10T22:19:34","guid":{"rendered":"http:\/\/www.freeautomechanic.com\/mechanic\/forum\/?p=34868"},"modified":"2022-03-10T14:19:37","modified_gmt":"2022-03-10T22:19:37","slug":"engine-overheating-with-the-air-conditioning-on","status":"publish","type":"post","link":"https:\/\/www.freeautomechanic.com\/mechanic\/forum\/2022\/03\/engine-overheating-with-the-air-conditioning-on","title":{"rendered":"Engine Overheating with the air conditioning on"},"content":{"rendered":"\n

After 3 years of trouble free driving, the car began to overheat with the air conditioning<\/a> on. Replaced the thermostat and it didn’t help. Any ideas? It is a 2009 Ford Focus SE.<\/p>\n\n\n\n

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I will go ahead and assume that your cooling system is full and working properly since the overheating only occurs when using the A\/C. Air conditioning causing the engine to overheat seems odd but happens more than you would think. As part of the air conditioning system it uses a separate fan or a High speed fan relay. Lets take a look at a wiring diagram to see if anything like that stands out. First I will look at the engine cooling fans wiring diagram. <\/p>\n\n\n\n

Engine Cooling Fans Wiring Diagram <\/h3>\n\n\n\n
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After taking a look at the above wiring diagram there are a couple of things to look at. One would be the High Speed Fan Control Relay. The other would be the wiring and or connections between the relay and the fan motor. And of course you would want to test to make sure the fan motor was operational not only on low speed but High speed also. You can test the fan motor by applying battery positive to the Brown wire to test High speed and Green\/White wire for low speed. You can swap out or test the relays<\/a> to see if that corrects the issue also. <\/p>\n\n\n\n