Hissing sound from dash after AC servicing

f1head · 2nd March 2010, 15:45

Hi Bhpians,

I got my car's (Maruti 800) AC serviced and gas topped up today , also the pipe from condenser to grill was changed.

After taking delivery of the car, I couldnt help but notice a hissing sound coming when the AC runs, I was afraid it was a gas leak. The garage person told me that its the condensor bearings making the noise

and that he will refill the gas if its a leak problem. I have taken his word but am not too sure.

Can anyone please tell me what could be the reason ? The hissing is very uneven, stops sometimes on idling and resumes when I give it race. It completely stops if AC is switched off. Inside the car it appears as though its coming from the left hand side underneath the dashboard, but could be an illusion.

tsk1979 · 2nd March 2010, 16:47

Nope, its less gas. When gas is less, it makes noise. Bearing noise comes from the engine bay, not from the dash

Jaggu · 2nd March 2010, 17:11

lol yeah its the gas moving around, might be a good idea to top it up. Switch on the AC and look through the glass window of the dryer bottle, if its bubbling after a min or two you need to fill gas.

f1head · 2nd March 2010, 19:24

Quote:

Originally Posted by Jaggu

lol yeah its the gas moving around, might be a good idea to top it up. Switch on the AC and look through the glass window of the dryer bottle, if its bubbling after a min or two you need to fill gas.

Thanks for replying, where is this dryer bottle ? Do you think this guy ripped me off ? He did charge for filling up the gas. He did the work in 58 minutes flat. Is there a way to measure the gas pressure ?

The cooling at this point is pretty awesome like new sedans

scorpian · 2nd March 2010, 21:53

What you are hearing is the gas spray,this basically happens when the orifice of the pipe is narrow or has sumthing sticking to it.

filling a lil extra gas will increase the pressure and may sort the issue if it dosent u will need to have the expansion valve checked.

f1head · 2nd March 2010, 22:10

Do I need to sort this issue ? I mean is it causing any damage to the car except for the hiss ?

Jaggu · 2nd March 2010, 22:35

Unless pressure is really low, it shouldn't be an issue. Open the bonnet and look for a aluminum bottle kinda thingie, this will have a glass window on the top.

ps: Some models might not have the window, so in that case you will have to get it checked by a competent AC technician.

f1head · 3rd March 2010, 18:27

Ok I saw the dryer bottle, it has some liquid which keeps vibrating inside, there is 1 bubble every 30 seconds-1 minute , otherwise its just vibrating water.

Alter_Ego · 3rd March 2010, 18:47

Quote:

Originally Posted by Jaggu

Unless pressure is really low, it shouldn't be an issue. Open the bonnet and look for a aluminum bottle kinda thingie, this will have a glass window on the top.

ps: Some models might not have the window, so in that case you will have to get it checked by a competent AC technician.

Jaggu,
Is this the case in Tata safari also? I mean does the dryer bottle looks the same as I am having the same problem and was till now ignoring it

Jaggu · 3rd March 2010, 21:59

1 bubble 30 sec -1 min is like ok gas fill, so not to worry. Do keep the ac running for few min and confirm, reving the engine a lil more also is a good idea. Just to rule out issue.

@alter ego: yup dryer bottle is similar for almost all cars.

SS-Traveller · 3rd March 2010, 22:12

Quote:

Originally Posted by f1head

...its the condensor bearings making the noise

Condensers don't have bearings! Could be a noise from the cabin blower bearings, but most likely it's low gas. Ask the AC guy to top up with gas again, and note for a change in hiss.

Otto · 3rd March 2010, 23:20

a hissing sound in the car wouldn't really be bearings. AFAIK, bearings when damaged or worn, don't hiss, they groan.
that hissing is probably the venturi effect of air passing over the vent flaps.
does it come when you turn the blower speed down?

vigsom · 4th March 2010, 20:38

Quote:

Originally Posted by f1head

Ok I saw the dryer bottle, it has some liquid which keeps vibrating inside, there is 1 bubble every 30 seconds-1 minute , otherwise its just vibrating water.

Looks fine to me.
as long as you feel the ac is effective,just don't bother.This noise is caused when liquid refrigerant expands -that's how the cooling happens.

b_ambat · 6th March 2010, 09:15

Hi f1head, don't bother to top up your gas now, the sound is from the evaporator(cooling coil) and that is pretty ok. I had the same issue and found that the hissing sound is from the expansion valve due to change of state (gas to liquid). Don't do any top ups or repairs until u feel the cooling is less.

vigsom · 7th March 2010, 09:34

Quote:

Originally Posted by b_ambat

the hissing sound is from the expansion valve due to change of state (gas to liquid).

it is the other way around - liquid to vapour
the loop is :

compressor(vapour)-->condenser(vapour to liquid)-->expansion valve(liquid to liquid+vapour)-->evaporator(vapour)-->back to compressor

2nd March 2010, 15:45	#1
f1head BHPian Join Date: Jan 2010 Location: New Delhi Posts: 126 Thanked: 3 Times	Hissing sound from dash after AC servicing Hi Bhpians, I got my car's (Maruti 800) AC serviced and gas topped up today , also the pipe from condenser to grill was changed. After taking delivery of the car, I couldnt help but notice a hissing sound coming when the AC runs, I was afraid it was a gas leak. The garage person told me that its the condensor bearings making the noise and that he will refill the gas if its a leak problem. I have taken his word but am not too sure. Can anyone please tell me what could be the reason ? The hissing is very uneven, stops sometimes on idling and resumes when I give it race. It completely stops if AC is switched off. Inside the car it appears as though its coming from the left hand side underneath the dashboard, but could be an illusion.
	() Thanks

2nd March 2010, 16:47	#2
tsk1979 Team-BHP Support Join Date: Feb 2005 Location: San Jose, CA Posts: 23,695 Thanked: 23,484 Times View My Garage	Nope, its less gas. When gas is less, it makes noise. Bearing noise comes from the engine bay, not from the dash
	() Thanks

2nd March 2010, 17:11	#3
Jaggu Team-BHP Support Join Date: May 2004 Location: Bangalore Posts: 20,381 Thanked: 17,277 Times	lol yeah its the gas moving around, might be a good idea to top it up. Switch on the AC and look through the glass window of the dryer bottle, if its bubbling after a min or two you need to fill gas.
	(1) Thanks

2nd March 2010, 21:53	#5
scorpian BHPian Join Date: Jun 2008 Location: GOA Posts: 856 Thanked: 1,297 Times View My Garage	What you are hearing is the gas spray,this basically happens when the orifice of the pipe is narrow or has sumthing sticking to it. filling a lil extra gas will increase the pressure and may sort the issue if it dosent u will need to have the expansion valve checked.
	() Thanks

2nd March 2010, 22:10	#6
f1head BHPian Join Date: Jan 2010 Location: New Delhi Posts: 126 Thanked: 3 Times	Do I need to sort this issue ? I mean is it causing any damage to the car except for the hiss ?
	() Thanks

2nd March 2010, 22:35	#7
Jaggu Team-BHP Support Join Date: May 2004 Location: Bangalore Posts: 20,381 Thanked: 17,277 Times	Unless pressure is really low, it shouldn't be an issue. Open the bonnet and look for a aluminum bottle kinda thingie, this will have a glass window on the top. ps: Some models might not have the window, so in that case you will have to get it checked by a competent AC technician.
	(1) Thanks

3rd March 2010, 18:27	#8
f1head BHPian Join Date: Jan 2010 Location: New Delhi Posts: 126 Thanked: 3 Times	Ok I saw the dryer bottle, it has some liquid which keeps vibrating inside, there is 1 bubble every 30 seconds-1 minute , otherwise its just vibrating water.
	() Thanks

3rd March 2010, 21:59	#10
Jaggu Team-BHP Support Join Date: May 2004 Location: Bangalore Posts: 20,381 Thanked: 17,277 Times	1 bubble 30 sec -1 min is like ok gas fill, so not to worry. Do keep the ac running for few min and confirm, reving the engine a lil more also is a good idea. Just to rule out issue. @alter ego: yup dryer bottle is similar for almost all cars.
	(1) Thanks

3rd March 2010, 23:20	#12
Otto BHPian Join Date: Feb 2010 Location: Navi Mumbai Posts: 86 Thanked: 109 Times Infractions: 0/1 (5)	a hissing sound in the car wouldn't really be bearings. AFAIK, bearings when damaged or worn, don't hiss, they groan. that hissing is probably the venturi effect of air passing over the vent flaps. does it come when you turn the blower speed down?
	() Thanks

6th March 2010, 09:15	#14
b_ambat BHPian Join Date: Feb 2010 Location: KL-7 Posts: 111 Thanked: 121 Times View My Garage	Hi f1head, don't bother to top up your gas now, the sound is from the evaporator(cooling coil) and that is pretty ok. I had the same issue and found that the hissing sound is from the expansion valve due to change of state (gas to liquid). Don't do any top ups or repairs until u feel the cooling is less.
	() Thanks