my 2013 qubo's AC performance is lacking. i had the freon/oil evacuated + restored for last 2 years in a row. there's no leaks. the symptom is that the airs blows full cold for about 2-3 minutes then it tapers off significantly and wont go back to full cold again unless the power switch is recycled. then it repeats again....tapers off hard after 2-3 min. Does the AC system take an input from the outdoor air temp sensor on bottom of the passenger mirror? Because, mine is defective and reads real low: when it's 80 degrees F outside it reads 34-35 F. could this sensor be my problem?
Technical Does Cabin AC take an Input from Outside Air Sensor?
- Thread starter nedro018
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Technical Does Cabin AC take an Input from Outside Air Sensor?
Is it a climate control system with a digital display, or a simple aircon system with an on off button for the aircon?
If its the climate control system then it takes the temperature from the outside, inside and the engine coolant. It also has a sun load sensor to work out how much the aircon is likely to have to work to maintain the temperature.
If it is a basic aircon system then it doesn't use any temperature sensors at all. and the temperature that comes out the vents is controlled by physics and the person sat in the driving seat.
thank you andy,
mine is the old style with on-off switch so yes i understand that the outside sensor is NOT involved here. copy.
can ask ask? what is possibly the culprit here? to my knowledge, in a car AC system, there are 4 working parts 1) comperssor 2) evaporator 3) expansion valve 4) condenser (on front of car)
a) so what are the symptoms of 1-4 above failing?
b) also, what are symptoms of a "leak" in the system ?
thank you so much for your time. the tech's in this country tend to "shotgun" replacement parts to fix the problem, one by one.
your extertise on the above is much appreciated!
mine is the old style with on-off switch so yes i understand that the outside sensor is NOT involved here. copy.
can ask ask? what is possibly the culprit here? to my knowledge, in a car AC system, there are 4 working parts 1) comperssor 2) evaporator 3) expansion valve 4) condenser (on front of car)
a) so what are the symptoms of 1-4 above failing?
b) also, what are symptoms of a "leak" in the system ?
thank you so much for your time. the tech's in this country tend to "shotgun" replacement parts to fix the problem, one by one.
your extertise on the above is much appreciated!
I'm going to cross off the evaporator and condensor from your list. While they are the coal face of the operation, they actually are completely dormant and the only way they can fail is to leak. So if they or any part of the system leaks out the gas you get no cold air con. So really there isn't much to say about them.
The compressor is made up of two parts. The compressor which compresses the refrigerant there are a number of ways it can fail. It could loose its seal and therefore leak out all the gas. It can seize up and not turn anymore, or it can loose its ability to compress gas if there is an internal mechanical fault. They are pretty complex on cars and very efficient. much more robust than the little compressor you'll find in a fridge.
As there are different ways they can fail you can get different or even variable symptoms.
The expansion valve is also a fairly dormant part. Its basically an aluminum block with a hole of a certain diameter in it. its possible that over time they can wear or warp and therefore loose the pressure or loose efficiency.
So as any part of the system can cause this. Normally what happens is as the refrigerant leaks out of the system, is that you'll usually first notice that the aircon can be quite noisey hissing from behind the dash. This is because with less pressure in the system there is less back pressure in the low pressure side. The gas then escapes more rapily through the expansion valve and it gets louder and louder.
Sometimes if the engine is loud like on a lot of diesels you might only notice the hissing when you turn off the engine and the gas will hiss for a little while till the pressure in the system evens out.
Sometimes you might only notice the problem when the air starts becoming more noticeably warm at the vents.
If I had to guess at what is wrong with yours I would look at the clutch on the compressor. if old these can slip and therefore it might work a bit, but if its slipping it soon warms up and then won't engage enough to cool the gas down. Turning it off may let the clutch cool down enough for it to start biting again.
You could pop the bonnet and take a look. You would expect to look at the compressor and when the clutch is engage the inner and outer parts of the clutch should move together, when not engage the inner part should be completely still and the outer part which is the pulley, should be spinning freely.
You could never have a situation where the outer pulley is spinning freely and the inner part is moving more slowly, that would suggest the clutch is slipping.
No problem.
AndyRKett one last question I promise: how do the AC shops detect a leaky system or tight system? Is this done when they connect the evacuation/recharge machines to car... The one that pumps in fresh freon/oil? Or is it by a separate test on a different tool? In other words: of I get a seasonal evac/recharge done, would they be able to have ALSO detected whether my system is leaking? Or is the leak test a different procedure? THANKS
Bonefish Blues
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Just a query for you OP - is your condenser rad all in good condition? I ask because our AC is struggling to cool at the moment, as an inspection predicted, because the fins have been falling off, which are obviously important to heat exchange.
vexorg, thanks. yeak, that pressure switch is conviently located next to my charge ports therefore easy to replace if req'd. probably allot cheaper than a compresser. as AndyRKett above states: it's likely not the condenser/evaporator or even the pressure switch as he says, they are all "dormant" parts. the compressor is crazy expensive, but as ARKett states: it "could" be the clutch on the compressor. so: it's either this clutch theory, or, the pressue switch. the car is only 10 years old with 77.8km and AC was not heavily used.
They can do a pressure test, (charge the system to a set pressure, then watch to see if it drops over a period of time.)
They can also do a leakage test if needed, by injecting coloured compressant (red?) into the system, and watching the system to see if any leaks out from joints, seals or pipework in the system.
My local garage does a pressure test as part of their recharge/top up procedure once they have degassed it, before they regas. They then decide whether a leakage test is needed according to the results of it.
(If the compressor clutch goes, you will probably hear it, (I did!!) makes one hell of a racket!!
)
I think this has been answered already, but just for completeness.
There are three ways to check for leaks on a system (4 if you could your ears and listening for the gas escaping)
1. connect the recharge machine up. Vacuum the gas out of the system then hold the vacuum for 30 minutes to an hour. If there are leaks then the system tends to lose the vacuum and fills up with air. The draw backs of this method is that the system spends most of its life under pressure so when you vacuum it, things like the seals and the shaft in the compressor can move and let the air in, even when pressurized there isn't a leak. An Aircon specialist I know spent weeks trying to fix a leak on a system on a classic car only for it to be some slight wear in the compressor letting air in, when vacuumed but sealing up when under pressure.
2. There is the fill it with something inert method, like nitrogen. Pressurize the system to full pressure and see if the system holds the gas. Ok for a check when regassing but does not show any slow leaks and a few days after a regas you can still find the system empty.
3. There are electronic "sniffers" machines that have a probe on the end of them that is able to detect the gas leaking out of the system. Can find bigger leaks ok but very slow leaks are harder to find especially in something like the condenser where there may be a tiny pin hole leak that you can't get the probe close enough too. Also affected by the wind blowing the gas away before the probe can detect it.
Sometimes the most reliable method is to had dye added to the system when it is refilled. Then when the gas leaks out the dye will leak out with it. This can then be detected with a UV light. If you have a UV light you could shine it around under the bonnet, the system may have previously been filled with dye and you might be able to find the leak. Best done in the dark as very hard to see the dye glow in bright sun light.
My advice for anyone with air-conditioning in their car is use it frequently. (mine is on all the time in my car when its not broken like it is at the moment with a compressor pulley issue) This keeps the oil circulating around the system, it keeps all the seals supple and will minimize the chance of the gas leaking out over time.
Then if you can avoid it, don't have it regassed unless it actually needs it. As soon as you open up the system and have it regasses it can upset seals and cause leaks that would not have happened if you just left it alone. In this respect the home refil kits are actually good as they don't vaccum the system they just top up the lost gas but should only be used when you know that there is gas in the system and the system is just weak, rather than when the car has lost all its gas and the aircon doesn't work at all.
Finally I'd advise not messing about with aircon unless you know what you're doing. there is gas under extremely high pressure. That can cause severe freeze burns if released onto skin and can suffocate in confined spaces as it displaces all the air. If a pipe bursts it will go with a lot of energy and can cause serious injury.
