EDIT: It turned out to be the bearing on the A/C pulley. It sounded exactly like rushing water, which is why I thought it had something to do with the coolant.
2005 Liberty KJ 3.7l 185,000 miles.
While I was driving yesterday, I noticed that my A/C was noisier than usual, like there was an extra sound in addition to the usual fan sound.
When I turned the A/C off, it made a loud 'roaring' sound for a few seconds. It's difficult to describe, but at first, I couldn't tell if it was coming from my Jeep or if a plane was flying overhead, so I guess it sounds a bit like a jet engine.
This symptom is repeatable - I turn on the A/C and it makes a quiet roar, then I turn it off, and it makes a loud roar for maybe 3-5 seconds.
With the A/C off, the vehicle seems to run normally. However, I have now noticed that there is a roaring sound for a couple of seconds on initial startup. I will start the engine, there will be a roaring sound for a couple of seconds, and then everything will act normal until I turn on the A/C.
Just to complicate things further, since the roaring sound is coming from the area by the dash, I thought maybe it was air trapped in the cooling system. I checked the coolant, and it was somewhat low. It was about 3/4" below the 'cool fill' line when the engine was cool. Is this low enough for air to make its way into the system?
When I went to top it up, I noticed that the coolant fill cap was loose. It's been a good 6 months since I last touched the cap (replaced temp sensor) so unless I have been driving around with a loose cap for 6 months, it must have loosened on its own somehow. It is a relatively new cap (I bought it about a year ago) but it doesn't seem to lock into place very positively, so I'm going to replace it asap.
I have not had any overheating issues, so I guess I didn't lose enough coolant to damage anything yet.
Is it possible that all this is related?
I know low coolant can cause air bubbles in the system and make a sound in the heater core, but I don't know if that would cause the A/C to make a sound when switched on and off?
2005 Liberty KJ 3.7l 185,000 miles.
While I was driving yesterday, I noticed that my A/C was noisier than usual, like there was an extra sound in addition to the usual fan sound.
When I turned the A/C off, it made a loud 'roaring' sound for a few seconds. It's difficult to describe, but at first, I couldn't tell if it was coming from my Jeep or if a plane was flying overhead, so I guess it sounds a bit like a jet engine.
This symptom is repeatable - I turn on the A/C and it makes a quiet roar, then I turn it off, and it makes a loud roar for maybe 3-5 seconds.
With the A/C off, the vehicle seems to run normally. However, I have now noticed that there is a roaring sound for a couple of seconds on initial startup. I will start the engine, there will be a roaring sound for a couple of seconds, and then everything will act normal until I turn on the A/C.
Just to complicate things further, since the roaring sound is coming from the area by the dash, I thought maybe it was air trapped in the cooling system. I checked the coolant, and it was somewhat low. It was about 3/4" below the 'cool fill' line when the engine was cool. Is this low enough for air to make its way into the system?
When I went to top it up, I noticed that the coolant fill cap was loose. It's been a good 6 months since I last touched the cap (replaced temp sensor) so unless I have been driving around with a loose cap for 6 months, it must have loosened on its own somehow. It is a relatively new cap (I bought it about a year ago) but it doesn't seem to lock into place very positively, so I'm going to replace it asap.
I have not had any overheating issues, so I guess I didn't lose enough coolant to damage anything yet.
Is it possible that all this is related?
I know low coolant can cause air bubbles in the system and make a sound in the heater core, but I don't know if that would cause the A/C to make a sound when switched on and off?
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