noise when air con switched on

peelaaa · 29th March 2019, 19:24

Hi,

When the air con is turned on there is a noise that changes with revs. Its not the whooping sound that can happen but a whirring type of sound. The engine seems a tad harsher when revved too.

When the air con is turned off, its much quieter.
Air con is cool but not as cold as I know they can get.

Am I looking at belts here or compressor?

Ian G · 29th March 2019, 19:35

Quote:

Originally Posted by peelaaa

Hi,

When the air con is turned on there is a noise that changes with revs. Its not the whooping sound that can happen but a whirring type of sound. The engine seems a tad harsher when revved too.

When the air con is turned off, its much quieter.
Air con is cool but not as cold as I know they can get.

Am I looking at belts here or compressor?

A common fault which (I think) usually points to the need for a new condensor..
Cheers Ian

Kev75 · 29th March 2019, 19:47

check the crankshaft pully and the belts.
Kev

Coups · 29th March 2019, 20:31

I had this. One garage suggested a new compressor was needed. I duly sourced one then read somewhere the noise may be due to low refrigerant/oil mix in the a.c. system. Sure enough an air con service sorted it out. That's all it was.

Air con service is recommended every 2 years I think so it might be worth considering before jumping to big repairs especially when you've noticed a drop in the systems performance.

Sent from my SM-G935F using Tapatalk

T-Cut · 29th March 2019, 21:35

Dtto Coups.
Mine had a revs variable whirring noise which disappeared after a fresh regas/lube job.
It just needs a regas.

TC

SD1too · 30th March 2019, 07:15

Hi Ian,

As you can see, there are a variety of suggestions for your symptoms.

As you have a diesel, I'm with Kev75. We've encountered this several times before. The extra load presented by the air conditioning compressor highlights a failing crankshaft pulley. I note your comment about engine harshness increasing.

A low air conditioning refrigerant charge, a failed low speed radiator fan or corroded condenser would not normally result in any abnormal noises or engine harshness. If you want to pursue this avenue, I would begin with the 'demist test' to check the radiator/condenser fan because you cannot assess the system's performance properly unless this is working.

Simon

roverbarmy · 30th March 2019, 08:01

My air con specialist tells me that most systems lose around 5% of their contents each year, so after year 1 = 95%, year 2 = 90% approx and so on.

T16 · 4th April 2019, 00:06

If you have a "grindy" compressor, never, ever run it again if you notice it making noise. Get the system re-filled, and if it is not damaged, it should return to almost silent operation.

If it does not, then it will likely slowly get worse over time and would eventually need replaced.

SD1too · 4th April 2019, 06:33

What's the latest on this Ian? Have members' suggestions been helpful? Have you made any progress?

Simon

SCP440 · 4th April 2019, 07:01

Quote:

Originally Posted by roverbarmy

My air con specialist tells me that most systems lose around 5% of their contents each year, so after year 1 = 95%, year 2 = 90% approx and so on.

That is a conservative estimate from what I have read but yes all systems do loose some every year and its worse if you don't use the system much.

What has to be remembered when the gas comes out so does some of the oil so just getting the refrigerant topped up every few years as Halfords usually do will end up with a system dangerously short of oil.

29th March 2019, 19:24	#1
peelaaa Posted a thing or two 75 cdti 2004 contemporary Join Date: Apr 2008 Location: meath Posts: 1,551 Thanks: 272 Thanked 80 Times in 58 Posts	noise when air con switched on Hi, When the air con is turned on there is a noise that changes with revs. Its not the whooping sound that can happen but a whirring type of sound. The engine seems a tad harsher when revved too. When the air con is turned off, its much quieter. Air con is cool but not as cold as I know they can get. Am I looking at belts here or compressor?

30th March 2019, 07:15	#6
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,338 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Hi Ian, As you can see, there are a variety of suggestions for your symptoms. As you have a diesel, I'm with Kev75. We've encountered this several times before. The extra load presented by the air conditioning compressor highlights a failing crankshaft pulley. I note your comment about engine harshness increasing. A low air conditioning refrigerant charge, a failed low speed radiator fan or corroded condenser would not normally result in any abnormal noises or engine harshness. If you want to pursue this avenue, I would begin with the 'demist test' to check the radiator/condenser fan because you cannot assess the system's performance properly unless this is working. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

30th March 2019, 08:01	#7
roverbarmy This is my second home Roverless + 1.7D Sportage Join Date: Aug 2014 Location: East Norfolk Posts: 7,050 Thanks: 729 Thanked 2,021 Times in 1,449 Posts	My air con specialist tells me that most systems lose around 5% of their contents each year, so after year 1 = 95%, year 2 = 90% approx and so on. __________________ Oil in my veins!

4th April 2019, 06:33	#9
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,338 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	What's the latest on this Ian? Have members' suggestions been helpful? Have you made any progress? Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

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29th March 2019, 19:47	#3
Kev75 Avid contributor Rover 75 Saloon Join Date: Apr 2012 Location: Nantwich Posts: 151 Thanks: 260 Thanked 41 Times in 34 Posts	check the crankshaft pully and the belts. Kev

29th March 2019, 20:31	#4
Coups Posted a thing or two Rover 75 Contemporary SE Join Date: Apr 2014 Location: Dundee Posts: 1,941 Thanks: 545 Thanked 520 Times in 402 Posts	I had this. One garage suggested a new compressor was needed. I duly sourced one then read somewhere the noise may be due to low refrigerant/oil mix in the a.c. system. Sure enough an air con service sorted it out. That's all it was. Air con service is recommended every 2 years I think so it might be worth considering before jumping to big repairs especially when you've noticed a drop in the systems performance. Sent from my SM-G935F using Tapatalk

29th March 2019, 21:35	#5
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,751 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	Dtto Coups. Mine had a revs variable whirring noise which disappeared after a fresh regas/lube job. It just needs a regas. TC

4th April 2019, 00:06	#8
T16 I really should get out more....... ZT CDTi 135, ZT260SE Join Date: Feb 2011 Location: Dundee Posts: 2,877 Thanks: 10 Thanked 331 Times in 213 Posts	If you have a "grindy" compressor, never, ever run it again if you notice it making noise. Get the system re-filled, and if it is not damaged, it should return to almost silent operation. If it does not, then it will likely slowly get worse over time and would eventually need replaced.