[guerve]

Hey guys! I've been having some issue with my 2007 335's A/C for the past 2 years. It started with warm air coming through half of the vents and cold air out the other half. After checking in this forum I learned that that happens when you're low on refrigerant and that I probably have a leak. So for the short term, I picked up a can of the A/C Pro refrigerant that comes with the low pressure gauge and I gave it some charge. Well that seemed to do the job and for a while everything seemed ok for about a year.

Well this year I started noticing a whirring noise that would change in pitch based off of engine rpm that I could especially hear when the rpm's are low. I gave the system a little more charge but that didn't do anything to remedy the sound. I did some more research and found that it could be the compressor wheel bearings or the system may be low on lubricant. Knowing that the cheaper of the 2 issues to fix was the lubricant, I ordered a set of coupler adapters for an old manifold gauge set i got from my dad. I also picked up a charge can of PAG 46 oil from autozone that contained 3oz of fluid ( 1 oz pag 46 oil, 1 oz 134a refrigerant, 1 oz ac line conditioner).

Yesterday I got to work. I connected to manifold set to my high and low lines. I burped the lines of the gauges to make sure I wasn't introducing any air into the system. Connected and added all of the charge can to the system. Cleaned up and made sure everything was running ok. I then ran the a/c for 20 minutes and found that the whirring noise went away .

The next day I started up my car and the noise was still gone. But... after driving around for an hour the noise started coming back. It still is a lot quieter than it was last week. So I guess I've got more work to do... So in figuring out next steps I went ahead and added some UV dye to help locate a leak. So moving forward, I've got a few questions hopefully someone would be so kind to answer.

Question 1:
After I was adding the oil charge, the readings for the low/high side was 30/200 psi and the ambient temperature was 72f. Going by the charts on this page http://acprocold.com/faq/r-134a-system-pressure-chart/
My low is slightly too low and my high is slightly too high meaning there is some blockage in the system. Are these numbers far enough beyond normal that I need to start disassembling the A/C system to hunt for blockage?

Question 2:
After I added the dye, I checked all of the lines visible from above the engine compartment and found no leaks. I know that a common failure point is the evaporator that is buried in the dash and that it's a monster bitch to get to. I still need to check from beneath the car and underneath the airbox. Any other suggestions for places to look?

Question 3:
I know that I'm eventually going to need to evacuate and vacuum my system. Do most car repair shops have the ability to properly dispose of the old refrigerant?

Question 4:
Does anyone have any more general advice or actions involving my current situation.

Thanks in advance guys. This board has been very helpful so far.

[lobotomy]

All good questions!
The advice I give are my opinions of how I would deal with evaluating the problem.
This is not a how to, nor checks you should do yourself, but rather a guideline for you to use to communicate with the certified A/C tech who will be diagnosing/repairing the system.

#1: Your #'s are very close, although you could have signs of slight blockage starting to occur, it could be slight gauge inaccuracy also.
If you had blockage, it would most likely be at the expansion valve (or an orifice tube assembly) depending on which system is used.

#2: I check for evaporator leaks by placing the probe of a leak detector inside the the A/C register (A/C outlet) with system on, A/C fan on also.
The appropriate leak detector for the Freon being checked must be used.

#3: Yes! Every repair shop dealing with A/C repair needs a license to do so that covers reclamation and safe handling of refrigerant.
It is a Federal requirement. It is illegal to vent this stuff into the atmosphere!

#4 I always like to know the condition of the Freon in the system I am dealing with before tampering with any A/C problem.
I do this by checking out the appropriate Temperature/Pressure correlation chart for the Freon being used.
I let the car sit overnight so that the temperature of the vehicle is relatively equal with the surrounding ambient air temperature. I DO NOT start the car at all during this check.
I then hook up a gauge to the low side, and use the chart to see if my ambient/Freon temp. matches the pressure I should be at. For
134a @ 69.24 degrees F=70 PSI;
134a @ 70.00 degrees F=71.1 PSI.......etc. etc.
While this does not tell me how much Freon is in the system, it lets me know if what is in the system is contaminated by moisture, or incompatible chemicals (additives, etc.).

When I pull a system into a vacuum I let it vacuum for several hours so that moisture is thoroughly removed & system is dry as can be. I look to pull down as close to 30" of vac. as I can get.
I like to keep it in vacuum at least 24 hrs; more if I can to insure no leakage is present!

[Sgt Fox]

Don't worry too much about the high side reading off. The main thing is to have the low side within range and that the high is roughly correct. Most systems I have seen have a different high side pressure than that table.

[MightyMouseTech]

If going to a shop, make 100% sure you tell them you put that non 134a refrigerant in the system. A lot of those self charge canisters contain propane. If pulled into a 134a machine it could explode, and possibly kill the tech.

Serious.

http://fridgehub.com/uploads/media/s...e_28_05_14.pdf