Air Conditioner Hiss Noise & Uneven Cooling Fix

O.K. folks. Had the same problem as a lot of folks on here. Uneven cooling out of our 140,000mile 1999 323i. Drivers side cool... passenger side warm and a hiss.

Never had a recharge as far as I knew (we are the original owner) and had only gotten louder with the hissing this summer. So I read the thread on here and decided maybe it was the low R134a since a lot of folks that seem knowledgeable said that. It didn't make sense to me as most of the air on the left side felt cool and most of the air on the passenger side felt hot I figured I had a good a/c system and a bad damper or actuator...etc.

Anyway I went ahead and did the R134a recharge and it cured the issue both sides are icy cold again and the hiss while still perceptible is at a greatly reduced volume. I may need to service the R134a with a little more refrigerant since I only put in about 2/3 of a 17oz can and I am showing 40lbs in the system at the gauge. I would feel pretty comfortable raising that pressure up to 50lbs. But for now things are working (good). The ambient temp here today is around 84 degrees and in my open garage under the hood where I was working it was probably 100 degrees.

The primary reason I am posting this is to let unexperienced DIY 'ers like myself know that this fix may in fact work fine on an otherwise properly working A/C system just one that has not had a service in quite a number of years. Fwiw I had approximatley 32lbs indicating on the Low pressure side of my system at the time I began the process. (that's with the a/c on full cold and fan up on high).

The inlet and cap for the low pressure side of the system is the rear cap near the firewall, and next to the well where the jump start terminal is tucked in. The high pressure inlet is apparently a little bigger and located up near the radiator not far from the Passenger headlight. Definiteley only play around with the low pressure side as the high pressure side apparently requires some pretty specialized equipment to avoid injury.

G/L...

Yep, worked for me too. The hissing is a lot less noticeable and appears to be working better. I considered this a top up and haven't had to touch this since last year.

Woo hoo!

-travis

Originally Posted by akosht

O.K. folks. Had the same problem as a lot of folks on here. Uneven cooling out of our 140,000mile 1999 323i. Drivers side cool... passenger side warm and a hiss.

Never had a recharge as far as I knew (we are the original owner) and had only gotten louder with the hissing this summer. So I read the thread on here and decided maybe it was the low R134a since a lot of folks that seem knowledgeable said that. It didn't make sense to me as most of the air on the left side felt cool and most of the air on the passenger side felt hot I figured I had a good a/c system and a bad damper or actuator...etc.

Anyway I went ahead and did the R134a recharge and it cured the issue both sides are icy cold again and the hiss while still perceptible is at a greatly reduced volume. I may need to service the R134a with a little more refrigerant since I only put in about 2/3 of a 17oz can and I am showing 40lbs in the system at the gauge. I would feel pretty comfortable raising that pressure up to 50lbs. But for now things are working (good). The ambient temp here today is around 84 degrees and in my open garage under the hood where I was working it was probably 100 degrees.

The primary reason I am posting this is to let unexperienced DIY 'ers like myself know that this fix may in fact work fine on an otherwise properly working A/C system just one that has not had a service in quite a number of years. Fwiw I had approximatley 32lbs indicating on the Low pressure side of my system at the time I began the process. (that's with the a/c on full cold and fan up on high).

The inlet and cap for the low pressure side of the system is the rear cap near the firewall, and next to the well where the jump start terminal is tucked in. The high pressure inlet is apparently a little bigger and located up near the radiator not far from the Passenger headlight. Definiteley only play around with the low pressure side as the high pressure side apparently requires some pretty specialized equipment to avoid injury.

G/L...

I am no master of A/C systems, but I have decent knowledge and trainning.

When you say "40lbs in the system at the gauge," are you actually referring to having 40lbs. of freon in your A/C system?

Are you referring to the same thing when you say "Fwiw I had approximatley 32lbs indicating on the Low pressure side."

I hope you got your descriptions mixed up and meant to refer to p.s.i. in your system. I dunno. But if you do have 40lbs. or 32lbs. of freon in your system, you're in for some trouble.

There should be a label attached on the underside of your hood, or on the body metal trim pieces to the left or right side of the radiator.

See pic:





Just trying to help (or clear the cobwebs in my head).


-Ruben

Originally Posted by DesertMotorWorks

I am no master of A/C systems, but I have decent knowledge and trainning.

When you say "40lbs in the system at the gauge," are you actually referring to having 40lbs. of freon in your A/C system?

Are you referring to the same thing when you say "Fwiw I had approximatley 32lbs indicating on the Low pressure side."

I hope you got your descriptions mixed up and meant to refer to p.s.i. in your system. I dunno. But if you do have 40lbs. or 32lbs. of freon in your system, you're in for some trouble.

There should be a label attached on the underside of your hood, or on the body metal trim pieces to the left or right side of the radiator.

See pic:





Just trying to help (or clear the cobwebs in my head).


-Ruben

Yes Yes yes.... pounds is abbreviated psi.... If your considering a DIY project on your a/c and reading about a gauge reading of 40 pounds and think you need to get a container(s) with 40 actual pounds of freon to put into your car you probably ought to think about taking the project to a shop.

Fwiw.

noob question:

1) So where can we buy this freon from?
2) can someone provide some pics of the procedure involved in topping up the freon?
3) are these guage readings you refer to, actually part of the car or do you have to buy some sort of guage for this DIY? if so, can you elaborate on what kind of guage to buy for checking the freon pressure?

Thanks a bundle!!

Originally Posted by inertia

noob question:

1) So where can we buy this freon from?
2) can someone provide some pics of the procedure involved in topping up the freon?
3) are these guage readings you refer to, actually part of the car or do you have to buy some sort of guage for this DIY? if so, can you elaborate on what kind of guage to buy for checking the freon pressure?

Thanks a bundle!!

I went to a local auto parts store. I bought a 17oz can of R134a with some oil and other stuff added. It had a gauge built right onto the hose valve assembly. I paid about $22.00.

What is the difference from the "High Pressure" and "Low Pressure" inlets?

Does the high pressure just fill recharge your AC faster than the low pressure? Or are their two different areas where the refrigerent is held?

I need to know because when I replaced my radiator, I accidentally loosened the wrong bolt where the "High Pressure" inlet is near and let some out. Now the AC doesnt blow cold, and I know I need to recharge it.

Would buying the kit and recharging it myself on the "low pressure" side do the trick?

Had my A/C recharged yesterday, and worked fine on the drive home and going to work this AM.
All is well.