ac hissing noise
gary v
08-07-2006, 03:31 PM
Hi everyone.When I have the air on in my 99 grand caravan, it makes a hissing noise from the vents when I shut the engine off.The noise fades away after 20-30 seconds. Noise is also heard in the back. Van has rear air & heat. It just started doing this recently. It still blows cool air. Any suggestions on why it's doing this. Thinking maybe low refrigerant?
RIP
08-07-2006, 10:14 PM
My 96 with rear air does the same thing. I want to say especially on very hot days. I don't worry about it as long as I get cold air.
BTW - Air bubbles in the sight glass on top of the drier are an indication of low freon. Temps less that 30 degrees cooler than outside air are another indication you might need servicing. Should be 30-40 degrees below outside air when checked at the center vent, on high, with the circulation button pushed, and upper vents selected.
BTW - Air bubbles in the sight glass on top of the drier are an indication of low freon. Temps less that 30 degrees cooler than outside air are another indication you might need servicing. Should be 30-40 degrees below outside air when checked at the center vent, on high, with the circulation button pushed, and upper vents selected.
gary v
08-08-2006, 08:06 AM
Thanks for the info. I will check temp diff & look for bubbles.I'll post what I find.
gary v
08-11-2006, 08:36 AM
Did not see a window on the dryer to check for bubbles & the temp diff was 28 deg's. Hopefully the hissing is caused by low freon. I guess I will just get it recharged & see if that gets rid of the noise.
typesix
08-11-2006, 12:12 PM
Chrysler uses vacuum actuators in many cars to move air dampers in the HVAC system. The hissing may be from one of the actuators.
MT-2500
08-11-2006, 12:28 PM
Did not see a window on the dryer to check for bubbles & the temp diff was 28 deg's. Hopefully the hissing is caused by low freon. I guess I will just get it recharged & see if that gets rid of the noise.
Low freon does not do hissing noises. Check for vacume leaks.
But as said some do it turned off. No problem if air is working good running.
But on the low freon the only way to proper check is with low and high side gauges.
What is your vent temptures?
And say no to them recharge death kits.
Wal Mart DEATH KITS
You cannot properly and safely recharge an air condition system with them.
The one side stop and go gauge does not tell you what your system is doing or is over charged or undercharged.
A overcharged or malfunction air condition system can reach over 500 lbs of pressure.
Enough to blow up that can or system and freeze you at first and the burn you or blind you and if any propane /butane in there blow and light you up.
The stop leak crap and who knows what kind of oil in the kits there will stop your system for sure.
Just like pouring super glue in it.
And some kits even contain freon with a butane mixer.
Good for a big blast.
If you are going to do it do it right and safe.
Here is what you need to start with.
http://www.ackits.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=AMA&Product_Code=66773
In the older days you could just throw in a can and go.
But over the years just adding freon is getting harder to do.
Newer systems have to have the correct amount of freon down to the ounces.
Most will need pumped down and vacuumed down and the right and amount of oil and a set amount freon charge installed to get the air to cool right and the system to last.
If an air condition is low there is usually a leak that needs fixed and also a lose of lubricating oil from system.
Also air and moisture enters a low system
If you are going to try to do it get the proper type air condition gauge set with the low and high side gauges.
Hook up the gauges and get a reading with compressor running at idle and at 2000 rpm on the high and low side.
Post back pressure reading and we can help you.
MT
Low freon does not do hissing noises. Check for vacume leaks.
But as said some do it turned off. No problem if air is working good running.
But on the low freon the only way to proper check is with low and high side gauges.
What is your vent temptures?
And say no to them recharge death kits.
Wal Mart DEATH KITS
You cannot properly and safely recharge an air condition system with them.
The one side stop and go gauge does not tell you what your system is doing or is over charged or undercharged.
A overcharged or malfunction air condition system can reach over 500 lbs of pressure.
Enough to blow up that can or system and freeze you at first and the burn you or blind you and if any propane /butane in there blow and light you up.
The stop leak crap and who knows what kind of oil in the kits there will stop your system for sure.
Just like pouring super glue in it.
And some kits even contain freon with a butane mixer.
Good for a big blast.
If you are going to do it do it right and safe.
Here is what you need to start with.
http://www.ackits.com/merchant2/merchant.mvc?Screen=PROD&Store_Code=AMA&Product_Code=66773
In the older days you could just throw in a can and go.
But over the years just adding freon is getting harder to do.
Newer systems have to have the correct amount of freon down to the ounces.
Most will need pumped down and vacuumed down and the right and amount of oil and a set amount freon charge installed to get the air to cool right and the system to last.
If an air condition is low there is usually a leak that needs fixed and also a lose of lubricating oil from system.
Also air and moisture enters a low system
If you are going to try to do it get the proper type air condition gauge set with the low and high side gauges.
Hook up the gauges and get a reading with compressor running at idle and at 2000 rpm on the high and low side.
Post back pressure reading and we can help you.
MT
gary v
08-15-2006, 05:07 PM
Just got the van back from the dealer. They said the hissing was was caused from low refrigerant. The system was recharged & dye was also added to check for leaks.Leaks were found at the suction line fitting, what fitting I don't know & also the evaporator. I was told the dash had to come out & it would cost about $1700 Canadian to fix, which I can"t really afford at this moment. Not sure how hard this would be for a diy job, but at least for now the hissing is gone & hopefully the charge will last until I can save up the cash.
MT-2500
08-15-2006, 05:40 PM
Just got the van back from the dealer. They said the hissing was was caused from low refrigerant. The system was recharged & dye was also added to check for leaks.Leaks were found at the suction line fitting, what fitting I don't know & also the evaporator. I was told the dash had to come out & it would cost about $1700 Canadian to fix, which I can"t really afford at this moment. Not sure how hard this would be for a diy job, but at least for now the hissing is gone & hopefully the charge will last until I can save up the cash.
It is hard to believe hissing is caused by low freon.
But glad you got it fixed and thanks for posting back how it went.
MT
It is hard to believe hissing is caused by low freon.
But glad you got it fixed and thanks for posting back how it went.
MT
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