When we put the A/C on the engine temperature starts to overheat?

MIKE PANKIEVICH

MEMBER
2002 JEEP LIBERTY
6 CYL
4WD
AUTOMATIC
42,000 MILES

When we put the A/C on the engine temperature starts to over heat. When we turn the A/C off the engine temperature returns to normal

Monday, June 8th, 2009 AT 11:50 AM

5 Replies

MHPAUTOS

MECHANIC
31,938 POSTS

Hi there,

Thank you for the donation,

Start with checking that the A/C condenser cooling fan is turning on, and have the radiator, cleaned & flow tested, not just a back flush with a hose as this will not really clean out and deposits that may be blocking many of the cores in the radiator, start here.

Mark (mhpautos)

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Tuesday, June 9th, 2009 AT 12:17 AM

SANCHEZ22

MEMBER
3 POSTS

Hello,
I have the same problem it only overheats when the a/c is on but I have changed the thermostat, radiator, there are no leaks and the fans are turning on. The water pump is fine too, at this point I am not sure what else it could be?

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Wednesday, September 14th, 2022 AT 8:13 PM

JACOBANDNICKOLAS

MECHANIC
108,262 POSTS

Hi,

Does this happen at any speed, or does it seem limited to in-town driving (stop and go)? Also, when the A/C is on, do you ever notice a squeaking from the A/C belt or anything that seems out of the ordinary?

Let me know. Also, it sounds as though you have done a lot of work already. Was the radiator cap replaced? Also, is there any noticeable usage of engine coolant?

Take a look at this link. It describes the symptoms of a faulty head gasket and what to look for. There are a few things that simply require inspection. Check them and let me know if anything mirrors what you find.

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know.

Joe

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Wednesday, September 14th, 2022 AT 8:45 PM

SANCHEZ22

MEMBER
3 POSTS

It only happens while driving in town, mostly when the car is stopped. The radiator doesn’t have a cap, only the coolant reservoir, it works fine. The coolant levels have not changed, it’s still on the “filled level”. When I had the radiator changed, it was not burped could that be a reason for it to overheat? Other than that, when I don’t use the A/C the car does not overheat.

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Wednesday, September 14th, 2022 AT 9:25 PM

JACOBANDNICKOLAS

MECHANIC
108,262 POSTS

Hi,

Okay, the idea that it happens when driving in town indicates it requires more airflow than the fan can provide.

So, two things. First, the coolant reservoir cap is vented. But it needs to hold a specific amount of pressure. If it isn't holding enough, the coolant's boiling level drops and can overheat easier.

Next, if the cooling system wasn't properly bled, absolutely that can cause what is happening. Don't laugh, but when it starts getting hot, does the heater work?

Let me know.

Joe