I hear a low ticking noise and low whining noise when the motor is running. I don't really hear it when the hood is closed unless I get close to it and Try to hear it. The low whining noise gets a little louder when the wheel is turned. After googling this whining sound and a sound it was making the night before it seems it may be the brake vacuum pump. I ordered one last night. Does this sound about right or am I going in a wrong direction? And what is the low ticking noise? Generally what type of Freon does the S40 require? To solve the cold air issue it was having we added freon but I have a bad feeling we added the wrong type. Could the wrong type of freon be causing any of these issues?

Things I have done in the 2 weeks I have had it... Front Rotor and brake change (me), balance and rotate tires (professional), Cleaned throttle body (me), cleaned MAF sensor (me), added Freon (hubby), checked fluids and air filters (me).

 

The whining is the either the power steering pump or the a/c compressor as you mentioned. It's not really supposed to be silent. Both of these are pretty busy positive displacement pumps generating respectable pressure.


If it is the a/c compressor, you can figure that out, because you can turn that off.


I am unaware of any S40 being made that would not take R134A, so I would think that is what you want. Generally refrigerant mixups on cars are avoided by looking at the fittings, but there might also be a label on the car saying that.

 

as to the freon, there should be a label somewhere under the hood (or even on the hood) indicating what your car has. Most likely its R134a based as most cars are these days. The nuances about what to buy have to do with whether you are charging an empty system or simply doing a topping off recharge. After opening the system you'd need a freon with the lubricating oil mixed in. For a simply recharge you don't want to keep adding oil. A single can shouldn't make that much difference. If you are leaking and need a recharge say every few months, that's a different matter and you'd probably want to have a shop recharge with a freon with dye. The thing to be careful with is overcharging the system. Freon is very temperature sensitive so your target fill pressure gets calculated based on ambient air temp. ie a car may have a target of 50 PSI at 65F but could be something like 40 PSI at 85F (you need a chart or a pressure gauge with a temp gradient).

As to the vacuum pump, why do you think it needs to be replaced? Its job it to keep pressure in the brake booster at idle. A typical symptom of a bad vacuum pump is a firm brake pedal when you start out first thing in the morning that goes away when you drive 100 feet or so... My '00 S40 has a noticeable brrr brrr cycling from the vacuum pump first thing upon start up which goes away once driving.

Have you tried a listening device (ie mechanics stethoscope or even a long ratchet) to hold against the vacuum pump? also do the same for the power steering pump as they can both whine and can help pin point the device. Does the noise sound like its coming from the driver's side of the engine or the passenger's?

 

I did a quick and dirty repair to the ac compressor as a temporary fix to see if that was my ac problem and it seems to be my disappearing cold air air problem. I think it's the vacuum pump because before the low whining noise there was an awful noise coming from the hood after a short test drive and lasted a few minutes after the car was turned off. After I popped the hood to figure out the location I turned the key and the noise started again. It took about 2 seconds to figure out it was coming from the silver thing in front of the battery. After letting it set over night while I googled what the thing even was it hasn't made the awful noise again just the whining noise. The ticking is coming from the engine itself. The car seems to be running rough when idling but not at rough as it was.

 

running rough at idle can be caused by weak spark (coil packs or plugs... this generation of Volvo's actually like the cheaper copper core plugs more than the expensive, so going OEM is a good play), a minor air leak (vacuum line, intake path) dirty idle air valve and sometimes dirty MAF or throttle body. Since you've already cleaned the MAF and Throttle body, you'd know if it was generally dirty in there or not.. I'd look around for vacuum lines/elbows etc. mist to see if anything gets sucked in and consider cleaning the idle air valve (its right there around the MAF and throttle body. The engine ticking is likely a lifter. You can say it adds "character" :-) but not something you can easily adjust.