Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 2nd March 2010, 15:45   #1
BHPian
 
Join Date: Jan 2010
Location: New Delhi
Posts: 126
Thanked: 0 Times
Default 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.
f1head is offline   Reply With Quote
Old 2nd March 2010, 16:47   #2
Team-BHP Support
 
tsk1979's Avatar
 
Join Date: Feb 2005
Location: New Delhi
Posts: 22,953
Thanked: 15,646 Times
Default

Nope, its less gas. When gas is less, it makes noise. Bearing noise comes from the engine bay, not from the dash
tsk1979 is offline   Reply With Quote
Old 2nd March 2010, 17:11   #3
Team-BHP Support
 
Jaggu's Avatar
 
Join Date: May 2004
Location: Bangalore
Posts: 17,749
Thanked: 7,470 Times
Default

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.
Jaggu is online now   (1) Thanks Reply With Quote
Old 2nd March 2010, 19:24   #4
BHPian
 
Join Date: Jan 2010
Location: New Delhi
Posts: 126
Thanked: 0 Times
Default

Quote:
Originally Posted by Jaggu View Post
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

Last edited by f1head : 2nd March 2010 at 19:30.
f1head is offline   Reply With Quote
Old 2nd March 2010, 21:53   #5
BHPian
 
scorpian's Avatar
 
Join Date: Jun 2008
Location: GOA
Posts: 270
Thanked: 112 Times
Default

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.
scorpian is offline   Reply With Quote
Old 2nd March 2010, 22:10   #6
BHPian
 
Join Date: Jan 2010
Location: New Delhi
Posts: 126
Thanked: 0 Times
Default

Do I need to sort this issue ? I mean is it causing any damage to the car except for the hiss ?
f1head is offline   Reply With Quote
Old 2nd March 2010, 22:35   #7
Team-BHP Support
 
Jaggu's Avatar
 
Join Date: May 2004
Location: Bangalore
Posts: 17,749
Thanked: 7,470 Times
Default

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 online now   (1) Thanks Reply With Quote
Old 3rd March 2010, 18:27   #8
BHPian
 
Join Date: Jan 2010
Location: New Delhi
Posts: 126
Thanked: 0 Times
Default

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.
f1head is offline   Reply With Quote
Old 3rd March 2010, 18:47   #9
BHPian
 
Alter_Ego's Avatar
 
Join Date: May 2009
Location: Melbourne
Posts: 443
Thanked: 98 Times
Default

Quote:
Originally Posted by Jaggu View Post
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
Alter_Ego is offline   Reply With Quote
Old 3rd March 2010, 21:59   #10
Team-BHP Support
 
Jaggu's Avatar
 
Join Date: May 2004
Location: Bangalore
Posts: 17,749
Thanked: 7,470 Times
Default

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.
Jaggu is online now   (1) Thanks Reply With Quote
Old 3rd March 2010, 22:12   #11
Distinguished - BHPian
 
SS-Traveller's Avatar
 
Join Date: Jan 2009
Location: New Delhi
Posts: 6,617
Thanked: 10,779 Times
Default

Quote:
Originally Posted by f1head View Post
...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.
SS-Traveller is offline   Reply With Quote
Old 3rd March 2010, 23:20   #12
BHPian
 
Otto's Avatar
 
Join Date: Feb 2010
Location: Navi Mumbai
Posts: 52
Thanked: Once
Default

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?
Otto is offline   Reply With Quote
Old 4th March 2010, 20:38   #13
Senior - BHPian
 
vigsom's Avatar
 
Join Date: Feb 2006
Location: AUH<->MAA
Posts: 1,722
Thanked: 581 Times
Default

Quote:
Originally Posted by f1head View Post
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.
vigsom is offline   Reply With Quote
Old 6th March 2010, 09:15   #14
BHPian
 
b_ambat's Avatar
 
Join Date: Feb 2010
Location: KL-7
Posts: 107
Thanked: 108 Times
Default

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.
b_ambat is offline   Reply With Quote
Old 7th March 2010, 09:34   #15
Senior - BHPian
 
vigsom's Avatar
 
Join Date: Feb 2006
Location: AUH<->MAA
Posts: 1,722
Thanked: 581 Times
Default

Quote:
Originally Posted by b_ambat View Post
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
vigsom is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hissing sound from speakers when not playing music. Please help. vishnuvijay In-Car Entertainment 62 12th March 2016 15:17
Fiesta 1.6 - Hissing sound yogi1771 Technical Stuff 7 21st August 2009 16:09
Hissing sound in NHC Vtec naman Technical Stuff 6 15th August 2008 17:20
Slight Hissing sound from ICE meconi In-Car Entertainment 9 29th January 2008 10:18
Hissing sound from belts in my Avalon adityapd Technical Stuff 17 29th September 2007 08:39


All times are GMT +5.5. The time now is 16:53.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks