engine wants to over heat when a/c is on

[Doug]

I have a 04 Durango 4.7,engine runs at normal temp but when I turn the a/c on the engine temp goes up to around 240,I can turn the a/c off and it will cool back down to normal.I don’t understand,any suggestions would be greatly appreciated.

Topic

[Konrad]

Is the condenser fan turning on when the AC is on?

[Doug]

It only has the one fan,I did replace the fan clutch about 1mnth ago,just started using the a/c a few days ago and noticed this

[Konrad]

We can assume the fan is working since it was replaced, but it doesn’t hurt to double check. Get the engine hot, shut it off, and try grabbing the fan blades and spinning them. If the fan spins freely, than your fan clutch is bad. Did you reinstall all the fan shrouds when you replaced the clutch? Is the radiator clear of debris and obstructions, and are the fins in good shape (not flaking away)?

Does it only get hot at idle and slow speeds, and cool off once you get on the highway? You may have a thermostat issue, or an air pocket in the system.

[Doug]

It heats up while rolling,I was wondering about the thermostat,do they go all at once or slowly,same w/water pump,to me it doesn’t make sense,but I’m not a real mechanic,I do my own work on my own cars and truck,but I do realize when I need help,thanks for the info and quick replies,I really like this forum because of that,I’ve been reading a lot on this forum and seems like a lot of knowledge floating around,thanks again,I’ll double check everything tomorrow,if it is the thermo.,I’ll probably go ahead and do the water pump while I’m there

[Konrad]

Typically thermostats will become stuck in various positions. It’s not really a gradual onset. One day they just stop in whatever position they see fit. Some will prevent the vehicle from warming up, and some will cause overheating.

Bleed the system thoroughly if you perform any work on the cooling system.

[Doug]

I must be blind,the condensor fan is on the drivers side,did not see it,oh well it’s working fine and I bled the system,seems to be working,taking it out for a drive shortly,thanks again

[Author]

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