A/C rumble / vibration after little use.

Post by **BlackBart** » 14 Jul 2025, 10:30

We don't use the A/C all that much - I roll down the windows. Now that it's scorch season I've caved and glad to have it.

When I flipped it on, there was a rumble you could hear and feel. Not engine noise. I turned it off and it disappeared. I went ahead and ran it on the highway and it seemed to quiet down and smooth out.

Is this the compressor, from not enough use?

Post by **scot850** » 14 Jul 2025, 11:52

Perhaps the bearings got a little dry from lack of use, and now using it, it has relubed itself?

Bit like the gasoline smell on our 06 XC70, there for one day then disappeared. Have to now wait and see if it reappears.

Neil.

Post by **Blacklab467** » 14 Jul 2025, 14:54

Could also be the cooling fan, that comes on with the A/C.

Post by **BlackBart** » 15 Jul 2025, 10:46

Different blower than the heat fan, or is it all one HVAC system? Because we have the squealing fan when it’s very cold, worth changing. Maybe I should take a stethoscope to the compressor at idle and try to trace it.

Post by **br0dy519** » 15 Jul 2025, 12:47

I think he's talking about the rad fan BB.

My engine struggles when the compressor is running, almost like it's going to misfire, oh well.. lol

Post by **BlackBart** » 15 Jul 2025, 13:23

Oh, right. I read a thread here about the blower fan getting gummed up.

Tested some this morning. Blower fan pushing nice cool air out. When A/C kicks on there’s a light clunk from sort of low RF area where the compressor is, and some noise and vibration. Stops when you cut the A/C. But I think much quieter than the other day when I first used it. We’ll drive it a bit and listen.

Vova585 · Post by **Vova585** » 15 Jul 2025, 14:32

My guess: since you haven't used it in a long time, most likely rust formed on clutch and pulley. It is possible that it formed in such amounts that when ac clutch engages it causes vibration to entire serpentine belt system. Since each time the ac clutch cycles some of this rust is falling off, you experiencing less issues.

Post by **scot850** » 15 Jul 2025, 15:19

So a bit like rusty brake rotors after a car has been sitting, and then them cleaning off with use?

Neil.

Post by **abscate** » 16 Jul 2025, 04:21

Sounds like a grumbly compressor. It will last 3.7 more seasons until it needs replacement

Post by **BlackBart** » 16 Jul 2025, 10:54

3.7, check.