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Old 7th March 2010, 11:32   #16
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Thanks vigsom, I typed it wrong its this change of state(liquid to vapour) which makes the sound.
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Old 22nd March 2012, 10:34   #17
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Default Re: Hissing sound from dash after AC servicing

Last week, i topped up AC gas for my ford ikon.

The cooling seems to be low, and when i opened the bonnet i could hear a slight hissing sound.

Then i could see water condensation from the inlet(like a leak) from where the compressed refrigent liquid enters the dash(as seen from the bonnet).

This obviously is a refrigerant leak right?
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Old 22nd March 2012, 10:48   #18
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Default Re: Hissing sound from dash after AC servicing

Quote:
Originally Posted by ramzsys View Post
Last week, i topped up AC gas for my ford ikon.

The cooling seems to be low, and when i opened the bonnet i could hear a slight hissing sound.

Then i could see water condensation from the inlet(like a leak) from where the compressed refrigent liquid enters the dash(as seen from the bonnet).

This obviously is a refrigerant leak right?
Since you have recently topped up the a/c gas, the sound can be the gas circulating through the system. The condensation is nothing but water vapour since the aluminium piping is cold and the surrounding air condenses on the outside and drips. You have nothing to worry if the cooling is fine.
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Old 22nd March 2012, 15:18   #19
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Default Re: Hissing sound from dash after AC servicing

Even I am facing the same issue in my Innova. I got the gas filled again but the hissing sound continues and sometimes gets really irritating and sometimes just ceases, Its not continuous and comes more often in the initial 15-20 mins of starting the AC. there was no such sound before. So what did the AC repair guy do wrong?
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Old 22nd March 2012, 18:54   #20
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Default Re: Hissing sound from dash after AC servicing

Quote:
Originally Posted by ramzsys View Post
Last week, i topped up AC gas for my ford ikon.

The cooling seems to be low, and when i opened the bonnet i could hear a slight hissing sound.

Then i could see water condensation from the inlet(like a leak) from where the compressed refrigent liquid enters the dash(as seen from the bonnet).

This obviously is a refrigerant leak right?
This should most likely be a leak; faced this issue last week with my Corsa.

Do one thing : run the a/c and along the a/c lines : from the compressor to the condenser and the compressor to the inlet into the dash, pour small quantities of a soapy liquid. There should be bubbles where there's a leak.

You could also go to A.S.S and check the refrigerant levels; if there's a leak, they would have dipped by now.
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Old 22nd March 2012, 20:10   #21
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Default Re: Hissing sound from dash after AC servicing

Quote:
Originally Posted by gpa View Post
Since you have recently topped up the a/c gas, the sound can be the gas circulating through the system. The condensation is nothing but water vapour since the aluminium piping is cold and the surrounding air condenses on the outside and drips. You have nothing to worry if the cooling is fine.
+1 to that.

The low pressure pipe to the Compressor suction sees condensation on the surface since it is at low temperature ; if this line is chilled,it indicates nromal refrigerant charge

The high pressure ones from the compressor to the condenser to the receiver drier all the way to the expansion valve is at high pressure.

Compressor to condenser ->hot
condenser to drier to exp valve->normal temperature
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Old 24th March 2012, 12:44   #22
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Default Re: Hissing sound from dash after AC servicing

As earlier mentioned Its less gas & your condensor doesn't have a bearing.
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Old 24th March 2012, 15:19   #23
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Default Re: Hissing sound from dash after AC servicing

How much is it to top up the gas, is it with the oil? I am hearing hissing too.
This happened after i changed my radiator.I may have loosened the condenser piping too. I got a quote of 1250 for an ikon.

Last edited by Catalyst_delhi : 24th March 2012 at 15:20. Reason: spelling
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Old 24th March 2012, 17:09   #24
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Default Re: Hissing sound from dash after AC servicing

^^ 1250 rupees is fine for leak test +vac pulling+refrigerant +oil

A simple 150g refrigerant top up should not be more than 200-250 rupees
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Old 24th March 2012, 20:34   #25
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Default Re: Hissing sound from dash after AC servicing

Quote:
Originally Posted by vigsom View Post
^^ 1250 rupees is fine for leak test +vac pulling+refrigerant +oil

A simple 150g refrigerant top up should not be more than 200-250 rupees
Thanks , When i separated the condenser from the radiator , the condenser connection came off approx 5 seconds, you reckon 150g ought to do it. Cooling has become slower + hissing noise
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Old 24th March 2012, 20:46   #26
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Default Re: Hissing sound from dash after AC servicing

^^ when you undid the ac condenser pipe,did you see refrigerant coming out?

suggest the following:
  1. check that the refrigerant in and out conn. on the condenser is tight
  2. hook up gauges to check system pressure levels ; with the ac on,the low side should read approx 40 psi and hi approx 150-200psi with engine at idle.
  3. raise to approx 2000rpm and you should see the low pr coming down to approx 30-35psi and hi going up to 250-275psi
if you see pressures lower than 20psi on low side,you'll just need to top up.

I got my Corolla topped up once quite long back - the cooling was almost non-existent and 200g made a sea of difference.
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Old 24th March 2012, 21:03   #27
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Default Re: Hissing sound from dash after AC servicing

Quote:
Originally Posted by vigsom View Post
^^ when you undid the ac condenser pipe,did you see refrigerant coming out?

suggest the following:
  1. check that the refrigerant in and out conn. on the condenser is tight
  2. hook up gauges to check system pressure levels ; with the ac on,the low side should read approx 40 psi and hi approx 150-200psi with engine at idle.
  3. raise to approx 2000rpm and you should see the low pr coming down to approx 30-35psi and hi going up to 250-275psi
if you see pressures lower than 20psi on low side,you'll just need to top up.

I got my Corolla topped up once quite long back - the cooling was almost non-existent and 200g made a sea of difference.
I have added new worm clips now , I saw greenish liquid coming out,oily as well. I will do what you mentioned shortly.
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Old 24th March 2012, 21:42   #28
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Default Re: Hissing sound from dash after AC servicing

^^ fine.

The pressures that I have mentioned are indicative ; the technician would know best.

All the best
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Old 24th March 2012, 22:50   #29
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Default Re: Hissing sound from dash after AC servicing

Is there any DIY test/symptom to find out whether the compressor is weak? I ask this because just by checking the pressure, the mechanic says this.
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Old 25th March 2012, 14:13   #30
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Default Re: Hissing sound from dash after AC servicing

if the refrigerant charge is normal and the compressor discharge line is not hot,then the compressor can be declared "weak" ;

your suction and discharge pressures would almost match

this condition can arise even if there is an internal leak in the compressor.

this ,can happen only after ,say a lakh of kms or even more.
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