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I wasn't sure where to post this, so I apologize if this isn't the right forum.

I have an 07 and I live in AZ and I rarely use my heat during the winter. The few times I did use it, it worked fine. I started noticing it was making a slight hissing/breathy noise that would go from high to low continuously then a considerably louder one when I'd switch it off. It got a little warmer so I stopped using it all together since I prefer the windows down.

We're starting to get into our higher temps so I turned on the AC and the same noise was present, only a little louder this time. I also noticed that it's blowing warm, but not hot air on the drivers side and cooler air on the passenger side. Then warm on both sides when I switch it to high. The heat works perfectly fine and I already checked the actuators and I can seem them moving when I turn the heat/cold dial.

Does anyone have any idea on where to start looking for the problem?

Thanks.
 

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I've heard before that the ducting behind the dash can overheat and partially deform / melt. Recommend searching on it either here or Google. I think @KOWBOY on here had a melted part replaced with stainless or some such.

Sent from my LG-H910 using Tapatalk
 

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Go through normal AC trouble shooting steps. With gauges, check low and high side pressure. Plenty of YouTube videos.

Hissing that happens all the time is usually an issue where blend doors aren’t opening and shutting as they should.

Hissing that happened for a time and is not longer happening could be a refrigerant leak. If you heard that in the cab, then it evaporators most likely.

Hissing could also just be your climate system doing it thing.

Regardless, start diagnosing AC with pressures to see if you have refrigerant in your system. If you do have refrigerant and it’s blowing warm, the you have bad compressor or blockages. Pressure differences between low and high sides can then tell you where blockage is, or if compressor has failed.
 

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Discussion Starter #5
Go through normal AC trouble shooting steps. With gauges, check low and high side pressure. Plenty of YouTube videos.

Hissing that happens all the time is usually an issue where blend doors aren’t opening and shutting as they should.

Hissing that happened for a time and is not longer happening could be a refrigerant leak. If you heard that in the cab, then it evaporators most likely.

Hissing could also just be your climate system doing it thing.

Regardless, start diagnosing AC with pressures to see if you have refrigerant in your system. If you do have refrigerant and it’s blowing warm, the you have bad compressor or blockages. Pressure differences between low and high sides can then tell you where blockage is, or if compressor has failed.
Sorry for the late response, I got busy and forgot to check back.

Thanks for the advice. I have yet to look at it, so I'll check everything mentioned. In the mean time, I have noticed that the lower the setting, the cooler it blows and the hissing gets quieter when I switch it to heat. I took a video of the hissing to see if anyone can listen to it and figure it out from that.

 

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Sorry for the late response, I got busy and forgot to check back.

Thanks for the advice. I have yet to look at it, so I'll check everything mentioned. In the mean time, I have noticed that the lower the setting, the cooler it blows and the hissing gets quieter when I switch it to heat. I took a video of the hissing to see if anyone can listen to it and figure it out from that.

https://youtu.be/HTz7IkVHD68
Impossible to tell from here, but could be a blower going bad + a slow refrigerant leak. Although I’ve never heard a blower make a metal grinding noise like that lol. I’ll PM you my phone number. You’re more than welcome to come over and I’ll give it a look-see, throw some gauges on there. I know on my TJ, the AC is ice cold, but my blower is slowly dying. So again, you could have coincidental, but separate issues. I’m off the next 2 days, and during the days otherwise...

Also, have you verified that controls switch to foot when prompted?
Also, when defrost is on, do those little side vents that Defoe the windows come on?
Open the hood, run AC. Does the AC clutch spin (middle of the compressor)? If it spins, is it constant or clicking on and off? Or is it stable with just the belt spinning the pulley?
 

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Discussion Starter #7
Impossible to tell from here, but could be a blower going bad + a slow refrigerant leak. Although I’ve never heard a blower make a metal grinding noise like that lol. I’ll PM you my phone number. You’re more than welcome to come over and I’ll give it a look-see, throw some gauges on there. I know on my TJ, the AC is ice cold, but my blower is slowly dying. So again, you could have coincidental, but separate issues. I’m off the next 2 days, and during the days otherwise...

Also, have you verified that controls switch to foot when prompted?
Also, when defrost is on, do those little side vents that Defoe the windows come on?
Open the hood, run AC. Does the AC clutch spin (middle of the compressor)? If it spins, is it constant or clicking on and off? Or is it stable with just the belt spinning the pulley?
I have a buddy with gauges and all that, but thanks for the offer. If I hit a snag, I may hit you up!

It's not a grinding noise, although I can see how you hear that. It's more of a hissing/breathy noise (sorry that's the best way I can think to describe it) that sometimes stays constant and other times gets higher and lower. It's really weird.

I took the panels off my dash on the drivers side and the glove box off of the passenger side. I can see the arm on the blend door move from the drivers side and everything on the passenger seems to be moving correctly. I plan removing the blend door and inspecting it one of these days when I get the time

Yes, the side vents blow air when defrost is on. All parts of the compressor are spinning and there is no clicking present.

I'm going to take it to my mechanic buddy one of these days when I have down time, I just figured I'd ask for help here to see if I can pinpoint it and save him the time.
 

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You said the hiss gets louder for a moment when you turn off the A/C. To me this indicates low refrigerant. You probably have a leak in your A/C system.
 

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Sorry for the late response, I got busy and forgot to check back.

Thanks for the advice. I have yet to look at it, so I'll check everything mentioned. In the mean time, I have noticed that the lower the setting, the cooler it blows and the hissing gets quieter when I switch it to heat. I took a video of the hissing to see if anyone can listen to it and figure it out from that.


Hey I know this is a bit of a shot in the dark, but my '08 JK is making the SAME EXACT NOISE!

Won't blow cold air. I live in NV and it is getting to the 100s.. need to fix asap.
 

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I was driving and old car for 10 years and in addition, I had a lot of problems with it. I had no money to buy another car and no one wanted to buy my car because they saw it is litteraly looking exhausted. So, I can't stay in a car without air conditioning but the system in that car was crushed and I should have been visit mechanic once in a week or once in two weeks. It faced almost everything: low compressor discharge pressure, high compressor discharge pressure, low/high suction pressure, compressor not working, evaporator not cooling and it had frozen evaporator coil. So better go to a mechanic and he will see what to do, because you never know what can happen. At the end I installed a large battery to the trunk and connected to a simple air conditioner which I bought here Aircon Servicing, Cleaning & Repairing Singapore | SoCool Pte Ltd and I felt as a true electronic engineer.
 

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My aircon vents had a lot of problems and I brought it to service. I highly recommend them as they were really professional and friendly. Do check them out.
 
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