Cooling fan on with AC?

[Avery4jc]

Well today was a great day.... I have been living without AC in my k3500 since I bought it but decided since I had a little extra cash enough was enough.
I took it down to a local shop and come to find out it was under $100 and I was out in under an hour with ice cold AC. Wish I would have gone in earlier.

There is a large auxillary fan that sits in front of my radiator that's never kicked on. I thought it was because I haven't overheated it (it gets hot pulling cuesta with a trailer but I'm spinning crazy RPM's and it's loud with the windows down so even if it did kick on I couldn't tell).
But today after leaving the shop I heard a new noise and sure enough it was the fan sitting there humming along.

So all that to ask this.... Is there a correlation between the two? When you kick the AC on does it kick the fan on because they assume the engine is working harder to turn the compressor and might get hotter?

 

[throttleissues]

They kick the fan on to flow air over the condenser, regardless of engine temp. If the engine's not running hot, then the cutch fan won't lockup, so there's not much airflow. The elctric fan makes sure there's airflow for the A/C condenser to stay cool, thereby enabling the heat transfer to cool the loose nut behind the wheel.

 

[Avery4jc]

Ahhh ok, that makes sense. I figured there was a good reason.

 

[Big Ray]

My experience with the last few trucks I've had is the a/c leaks down juuusssst enough to keep the a/c from kicking on.

Unlike a home system which is soldered, a vehicle system has threaded hoses which leak a bit over time as vehicle is flexed and vibrated.

Jump the pressure switch long enough to kick the clutch on & see if it tries to cool...

if it does, add freon and be cool!

 

[4X4HIGH]

Yep, the electric fan should come on when ever the A/C is turned on. Not all people know this but it is a good thing to know in case you're ever driving and the engine starts to overheat just turn the A/C on and you'll have the extra cooling from the electric fan. The same goes for the heater if you don't have A/C, turning it on will help to disapate heat although you might cook in the cab it's better than smoking an engine.

 

[throttleissues]

When I had trouble with my Heep Cherokee overheating, I unplugged the A/C compressor clutch and turned on the A/C. That way the electric fan would run all the time.

 

[Avery4jc]

My experience with the last few trucks I've had is the a/c leaks down juuusssst enough to keep the a/c from kicking on.

Unlike a home system which is soldered, a vehicle system has threaded hoses which leak a bit over time as vehicle is flexed and vibrated.

Jump the pressure switch long enough to kick the clutch on & see if it tries to cool...

if it does, add freon and be cool!

I think you misunderstood my first post. I took it into a shop and they checked it for leaks and charged it up so now it blows ice cold. My question was just about the aux cooling fan mounted in front of the radiator.

Yep, the electric fan should come on when ever the A/C is turned on. Not all people know this but it is a good thing to know in case you're ever driving and the engine starts to overheat just turn the A/C on and you'll have the extra cooling from the electric fan. The same goes for the heater if you don't have A/C, turning it on will help to disapate heat although you might cook in the cab it's better than smoking an engine.

Hmmm that's good to know. I always knew about the heat thing but figured the extra cooling the fan on the front would provide with the AC on would be insignificant since it would also be working harder to turn over the AC compressor.

 

[throttleissues]

Hmmm that's good to know. I always knew about the heat thing but figured the extra cooling the fan on the front would provide with the AC on would be insignificant since it would also be working harder to turn over the AC compressor.

It works the engine a little harder, and it transfers heat in front of the radiator. It works to cool down some vehicles, but it will also overheat some worse than before. That's why I unplugged the comp for the extra cooling.