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Discussion Starter · #1 ·
Hi all. I have a 2011 S60 T6 and am having issues with the AC. Blows very hot in start and stop traffic and starts to blow cold once I get to and stay at highway speeds. Also occasionally works in slower speeds but not for long. Any possibilities or possible fixes would be appreciated!
 

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It' probably failed engine cooling fans. Better get it looked at sooner rather than later.
If my A/C was blowing hot, I would try and put new refrigerant in before I brought it to a mechanic. A $30 kit from any big box store is a cheap way to see if it's just low on freon. If that fixes it but the problem comes back before the end of the summer, there's a leak.

EDIT: See zenmervolt's post below for why this isn't a great idea on a car you plan on keeping for a while.
 

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It' probably failed engine cooling fans. Better get it looked at sooner rather than later.
+1

Check the cooling fan(s) first. This sounds like your are not getting enough air over the condenser. Driving at 50+ mph should generate enough airflow through the condenser without the fans. Just start the car, turn the A/C on to max cool and see if the fan(s) run when the compressor is running.
 

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He mentioned it occasionally works at lower speeds. I'm guess it's a slipping A/C compressor clutch.
 

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It' probably failed engine cooling fans. Better get it looked at sooner rather than later.
If my A/C was blowing hot, I would try and put new refrigerant in before I brought it to a mechanic. A $30 kit from any big box store is a cheap way to see if it's just low on freon. If that fixes it but the problem comes back before the end of the summer, there's a leak.
A properly functioning A/C system does not get "low on freon." If adding refrigerant helps, there is a leak. Period. A properly functioning A/C does not lose refrigerant, so if it's low enough to need more, there's a leak somewhere that needs to be fixed.

Any leak, even a slow one, in an A/C system should be fixed. This is because the oil in an A/C system is miscible in the refrigerant - this means that the oil mixes with the refrigerant and if you are losing refrigerant, you are also losing oil. The $30 "recharge" kits generally do not contain oil and using them to recharge a system will result in it being low on oil, accelerating wear and making future problems more likely. It will also not stop the leak, so you are guaranteed to eventually need to recharge it again, by which point it will have lost even more of its oil.

Those $30 recharge kits are good for one thing: masking a problem long enough for a dishonest seller to prevent a buyer from noticing that the A/C needs repair.

In the OP's case, I would first check for blockage of the the condenser and that the fans are coming on appropriately at low speeds. Operation at speed but not when stationary or moving slowly suggests that the condenser is not able to shed enough heat.

I would also see if revving the engine while stationary improves cooling. If cooling is dependent on engine RPM, that does indicate low refrigerant or a slipping compressor clutch. If the compressor clutch checks out, then at that point, a leak detection kit and repair of the leak is indicated. Simply adding refrigerant without addressing the leak is not a good long-term solution due to the oil loss issues mentioned above.

Remember that if the system is opened to replace a seal or leaking line you must also replace the receiver/drier and pull a hard vacuum on the system for several hours to ensure that all moisture is removed prior to recharging either based on refrigerant weight or by superheat/subcooling.
 

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The first thing I would check is the amount of "freon" in the system. Your local mechanic can check this. I would do this before adding any freon so you don't overcharge the system and blow out a seal.
Your mechanic can also put a dye in the system and check for leaks.
 

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A properly functioning A/C system does not get "low on freon." If adding refrigerant helps, there is a leak. Period. A properly functioning A/C does not lose refrigerant, so if it's low enough to need more, there's a leak somewhere that needs to be fixed.

Any leak, even a slow one, in an A/C system should be fixed. This is because the oil in an A/C system is miscible in the refrigerant - this means that the oil mixes with the refrigerant and if you are losing refrigerant, you are also losing oil. The $30 "recharge" kits generally do not contain oil and using them to recharge a system will result in it being low on oil, accelerating wear and making future problems more likely. It will also not stop the leak, so you are guaranteed to eventually need to recharge it again, by which point it will have lost even more of its oil.

Those $30 recharge kits are good for one thing: masking a problem long enough for a dishonest seller to prevent a buyer from noticing that the A/C needs repair.

In the OP's case, I would first check for blockage of the the condenser and that the fans are coming on appropriately at low speeds. Operation at speed but not when stationary or moving slowly suggests that the condenser is not able to shed enough heat.

I would also see if revving the engine while stationary improves cooling. If cooling is dependent on engine RPM, that does indicate low refrigerant or a slipping compressor clutch. If the compressor clutch checks out, then at that point, a leak detection kit and repair of the leak is indicated. Simply adding refrigerant without addressing the leak is not a good long-term solution due to the oil loss issues mentioned above.

Remember that if the system is opened to replace a seal or leaking line you must also replace the receiver/drier and pull a hard vacuum on the system for several hours to ensure that all moisture is removed prior to recharging either based on refrigerant weight or by superheat/subcooling.
Great post. Prior to my V60, I've only ever owned cars that weren't worth doing big A/C system repairs if the $30 kit gave me cold air for the whole summer. I guess I still need to get out of that mindset with my new car. They do make those recharge kits with oil and stop leak though. I plan on using one on my wife's 2006 Hyundai this weekend.
 

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Great post. Prior to my V60, I've only ever owned cars that weren't worth doing big A/C system repairs if the $30 kit gave me cold air for the whole summer. I guess I still need to get out of that mindset with my new car. They do make those recharge kits with oil and stop leak though. I plan on using one on my wife's 2006 Hyundai this weekend.
I don't like the stop leak kits either, in my experience they tend to gum up compressors. But you make a good point about getting through a summer with s slow leak on a throw-away car.

I've generally been lucky; the A/C in my '98 S70 still works perfectly with the original refrigerant after 21 years and while I did have to replace a valve core and the expansion valve on my '86 951 even that doesn't leak with 33- year-old hoses now that the new valve core is in place.
 

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Discussion Starter · #10 ·
I figured I should add more context to this now. Compressor does engage when AC is turned on. I went ahead and bought an AC Pro bottle so I could at least check my pressure. It was way up in the red between 60 and 150 (that’s the only readings you’re given at that point. I figured maybe some dumb previous owner overcharged so I attempted to relieve the pressure. Probably stood there draining the valve to an acceptable range for 5 minutes at least. Rag I was using was not cold at all prior to draining. Maybe slightly below ambient temp so it’s almost as if it’s just pure air coming out. I’m figuring it’s quite possibly a leak from all this but can’t understand why I would consistently get the same intermittent AC performance over the course of a few months (it’s only been relatively warm here for a month or 2).

I’m definitely NOT and AC guy so I’m not sure where I stand at this point. About to take it for a highway speed drive and see if I get the same intermittent results following letting all that pressure out.
 

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I figured I should add more context to this now. Compressor does engage when AC is turned on. I went ahead and bought an AC Pro bottle so I could at least check my pressure. It was way up in the red between 60 and 150 (that’s the only readings you’re given at that point. I figured maybe some dumb previous owner overcharged so I attempted to relieve the pressure. Probably stood there draining the valve to an acceptable range for 5 minutes at least. Rag I was using was not cold at all prior to draining. Maybe slightly below ambient temp so it’s almost as if it’s just pure air coming out. I’m figuring it’s quite possibly a leak from all this but can’t understand why I would consistently get the same intermittent AC performance over the course of a few months (it’s only been relatively warm here for a month or 2).

I’m definitely NOT and AC guy so I’m not sure where I stand at this point. About to take it for a highway speed drive and see if I get the same intermittent results following letting all that pressure out.
Pressure reading at only one port tells you basically nothing about the system.

That said, a low side pressure that high makes me think there might be a blockage in the lines somewhere or a stuck expansion valve (assuming the P3 cars use an expansion valve and not an orifice tube, I haven't checked what system Volvo uses). I'm assuming that you don't have access to a set of manifold gauges to get pressure readings on both the high and low sides of the system?
 

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Discussion Starter · #12 ·
I don’t but I might invest in some just to get the high side reading. After about a 45 minute drive at 70mph, I had 0 cold air the whole time. Checked the pressure of the low end at home and it was still at around 35-40 psi. I also noted of a very faint sound that I don’t believe was there before that only happens when the AC turns on. It’s a very slight windy noise. Like the exact same noise you’d hear if you’re putting air inside a tire. Maybe I’m just paranoid and it was always there but I don’t think that’s the case.
 

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I don’t but I might invest in some just to get the high side reading. After about a 45 minute drive at 70mph, I had 0 cold air the whole time. Checked the pressure of the low end at home and it was still at around 35-40 psi. I also noted of a very faint sound that I don’t believe was there before that only happens when the AC turns on. It’s a very slight windy noise. Like the exact same noise you’d hear if you’re putting air inside a tire. Maybe I’m just paranoid and it was always there but I don’t think that’s the case.
Was the A/C on when you checked the pressure before? If not, I can pretty much guarantee that your system is now low on refrigerant. Possibly to the extent that it won't run because the low pressure switch isn't triggered consistently.

When the A/C is off, pressure will equalise across the expansion valve so seeing high readings on the "low" port would be expected with the system off.

As a rough guide, low side pressure of 35-40 psi is generally appropriate for a running A/C system with an ambient temperature in the low to mid 70s (Fahrenheit) and I would expect the high side to be reading somewhere in the 140-170 psi range. Every system will be a bit different but this should be in the ballpark.
 

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Discussion Starter · #14 ·
Yes the AC was on each time with compressor engaged as well. Ambient temp was about 85 so maybe the pressure is slightly low. That being said the fact that no Freon was coming out when I relieved the pressure baffles me.
 

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Yes the AC was on each time with compressor engaged as well. Ambient temp was about 85 so maybe the pressure is slightly low. That being said the fact that no Freon was coming out when I relieved the pressure baffles me.
When you say that the compressor was engaged, do you mean that the A/C button was on or do you mean that you verified that the clutch was positively engaged and driving the compressor instead of just letting the pulley spin?

If you turn the A/C off and on, what changes do you see with the pressure reading?
 

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Discussion Starter · #16 ·
I have confirmed that the compressor is engaged by looking under the manifold, not just that the pulley is pulling. When AC is turned off, compressor is off. AC on compressor on, as it should function. I haven’t got a reading with the AC off.
 

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I have confirmed that the compressor is engaged by looking under the manifold, not just that the pulley is pulling. When AC is turned off, compressor is off. AC on compressor on, as it should function. I haven’t got a reading with the AC off.
Ok, good. I know that when I started I had a hard time remembering to check that the clutch was engaging. 🙂

I'm more interested in what change you see if/when the compressor cycles. When the compressor kicks on, low side should draw down immediately and bleed up when the compressor kicks off. The pressure with the system off and having sat for a minute or two is less important at the moment.
 

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Discussion Starter · #19 ·
Alright so: After draining pressure yesterday, today I checked and with AC on (albeit it’s about 10 degrees cooler outside) PSI is 30. With AC off it’s about 35. Also intermittent AC is no longer intermittent and just doesn’t get cold at all.
 

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everything zen told you is exactly correct. Your bouncing around trying this thing then that. I suggest ,and what i would do is go back to square one. In other words, you'll need a vacuum pump to pull the system down ,then check for leaks. If no leaks , re charge the system and don't forget the oil. I'm assuming that all components are working, and has never been left "open" .
If this is beyond your ability or you don't have the tools, you gonna have to bite the bullet and take it to someone.
I've done this for decades, converted R-12 systems to R-134, etc., it's not too complicated....but it is a process....
Since you seem to be new at this, when the system is not engaged, for example engine not running at all, the high and low side readings will be equal. Practically every car i've ever worked on usually sits around 100psi. Understand, that is NOT what you fill it to, i'm just trying to get you to see how the system works.
 
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