Car AC temperature help

[webmonkeyuk]

Ive been noticing lately as the weather is warmer that my AC is non existent temperature wise, it turns on and ive checked the compressor spins so i presume its working but theres no difference in temperature with it on or off and the low pressure pipe is not cold to touch after its been on awhile (ive seen that it should be frosty to touch after reading on the net). On a mild/warm day its between 15-23c out the vents, i had it regased last year as it was not getting cold and as far as i can remember it was cold after it had been regased. It was actually completely empty when the did it, something like 0.07ml of gas was recovered.

Ive bought a STP hose/gauge to check the gas level and its showing right on the low/filled mark at 25psi so im wondering does it sound like it needs a regas again or could it be something else if so what could i check for next. Could the compressor spin but not pump the gas around? or could the gauge be showing more than is in it and its a false reading?

thanks

 

[ttaskmaster]

Sounds more like you need to get it checked for leaks first...

 

[sovietspybob]

If the pressure is below a certain threshold it just won't run to protect the system, so it may have just dipped below whatever the pressure switch is set to and you need a re-gas. But sounds like you have a slow leak somewhere if its lost enough in 12 months for it to stop working.

 

[peige]

The machines that top them up are supposed to detect leaks but in my experience don't detect the leaks that take months to happen. I'm afraid you're going to have to ether put up with a yearly top up or warren of possible fixes which can range from a simple o ring leaking to a hole in the air con rad (although these tend to be massive leaks). Your supposed to be able to use a UV light to see the gas leaking out again, its just luck and money here..

Best policy is to run it often, even in the winter to stop the seals drying out.

 

[Howard]

If it's fairly modern then chances are it's a variable-displacement compressor which means there is no clutch; the pulley is permanently engaged and the pumping is controlled internally via a valve. So the fact that it is spinning will be a red herring. You'll know if it's an older clutched compressor as you'll usually hear a click/clonk when it engages.

If the high side pressure is only 25PSI then you've got bugger all refrigerant, meaning there is a leak. As Peige said above, the automated leak tests are very basic and will only really tell you that there is a gaping hole somewhere. An AC technician will be able to more easily pinpoint smaller leaks.

Even if you don't use the system all winter I wouldn't expect it to stop working after a year. I guess it's up to you whether or not you investigate it, as it can get quite expensive. What car is it?

 

[webmonkeyuk]

Thanks guys, I do make sure I run it even in winter every few weeks so it's not left. When they did the refill the guy said the refrigerant is also a lubricant which is never realised tbh. I think it's clutched compressor because you see it spin when the ac is turned on but if it's not on it doesn't spin.

It's the low side that's showing around 25psi, not sure what the high pipe shows as the guage only works on the low pipe. If I bought some of the UV gas could I put that in if there's still some refrigerant in? Or will it over fill it. Oh btw car is a 2012 i20 Hyundai. Obviously if there's a small leak I'd probably just refill every year. I will ask around and see how much for a AC technician to have a look too

Thanks again chaps

 

[Howard]

There's no reason not to just run it all the time really. It's better for the system and it'll give you a more pleasant atmosphere inside.

25PSI on the low side sounds about right, maybe a wee bit low. But this alone isn't really indicative of how much refrigerant is left.

I think you need to get it looked at by someone with the right knowledge and equipment.

 

[RJC]

Was 25 psi standing pressure or with the compressor switched on?

when running this is about right - equates to 0 -1c saturation temp.

If standing pressure it should be around 100 psi + (6 Bar +) for 20c ambient, when the system is off the pressures will equalise.

 

[IAmATeaf]

Fixing AC problems can be a money pit. On my last car I had something similar, lacking AC so took it to specialist. He plugged his machine, then regassed, super cold but within a week back to no AC. So he did his tests again, again regassed it, same thing. Then fault attributed to hole in the condenser, so had that swapped out, then dodgy compressor and so it went on.

In the end I gave up, ran it without AC until I eventuall parted the car for something else.

 

[webmonkeyuk]

It's 25psi running and I've checked after it's been stood overnight and hasn't been used and it shows in the alert section at about 50psi. When it's running I can hear a quiet sort of rattling sound, it's not massively loud but it's noticeable.

 

[Spartacus]

Car AC should generally be blowing somewhere between 2c - 6c at the vent on the coldest setting if it’s working correctly.

funnily enough I checked the temp at the vent from my cheap run-around 07 Focus earlier today. Ambient outside temp was 20c and the temp at the vent was 1.5c on the coldest setting.

 

[andy_mk3]

Car AC should generally be blowing somewhere between 2c - 6c at the vent on the coldest setting if it’s working correctly.

funnily enough I checked the temp at the vent from my cheap run-around 07 Focus earlier today. Ambient outside temp was 20c and the temp at the vent was 1.5c on the coldest setting.

Of all things I think the lowest I've seen was in a Vectra reaslding something like -2c out the vent!


Op: take it to be diagnosed, simple as.

 

[Spartacus]

Of all things I think the lowest I've seen was in a Vectra reaslding something like -2c out the vent!


Op: take it to be diagnosed, simple as.

Ambient temp and humidity make a difference too, if it’s 30c+ you won’t get temps at the vent below 0c.

 

[geekman]

This is one of those cases where you need to take it to someone who really knows what they’re doing - you can’t diagnose AC issues easily yourself like you can with other mechanical issues.

A good mechanic should pressure test the system, re-gas it if no leaks are detected, and inject a UV dye that will show where it’s leaking out from if the leak is too small to be detected by the machine.

Last time I had an AC issue, the mechanic said it was a compressor problem. I took it to an expert who only fixes AC systems, he found a small leak in one of the lines and fixed it for less than £50. It’s been fine ever since and regularly gets used in 35c+ heat.

 

[IAmATeaf]

You really need to take it to an AC specialist, Kwik fit and the like will simply plug a machine in and that will be it.

 

[RJC]

Indeed, It needs a proper pressure test with OFN and leak spray.

You have enough refrigerant to keep the unit running but not enough to do any duty - also needs the head pressure checked as well.

 

[webmonkeyuk]

Just a follow up, I ordered a home refill kit and filled it up to round about 40psi. The temperature is now down to a steady -15 -20 out the vents from before where it wouldn't go below +15. Obviously I'm going to keep an eye on the fill levels as I do suspect they could be a leak. Thanks for the help and suggestions chaps

 

[Merlin5]

I'm taking my Auris tomorrow to be re-gassed as there's no temperature difference between normal fan blower and when the a/c switch is enabled. Mechanic said he puts a dye in the coolant which will make it easier to see if there's any leaks. I hope it's just a straight forward re-gas and no leaks. He's charging me £70 + vat.

 

[Howard]

Just a follow up, I ordered a home refill kit and filled it up to round about 40psi. The temperature is now down to a steady -15 -20 out the vents from before where it wouldn't go below +15. Obviously I'm going to keep an eye on the fill levels as I do suspect they could be a leak. Thanks for the help and suggestions chaps

MINUS 15 to 20? That's not right at all. I think you need a new thermometer. That or it's going to last 5 minutes until your entire system freezes up and/or fails spectacularly.

 

[RJC]

That's better than some walk in cold rooms I've had the misfortune to work on!