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Recharging 2001 BMW 330ci... recharge and oil advice?

wamcneil on Mon June 06, 2011 10:18 PM User is offline

Year: 2001
Make: bmw
Model: 330CI
Engine Size: 3.0
Refrigerant Type: 134a
Ambient Temp: 95
Pressure Low: ?
Pressure High: ?
Country of Origin: United States

Hi all,
Sorry for the lack of pressures, I have not hooked the gauges up yet- they're in my shop and I'm at home. My questions mainly regard oil and recharging procedures.
My system has apparently leaked down over the last several years and I've got to make a trip this week...
The last A/C service was an evaporator replacement done by the dealer under warranty in 2005. About a year later, I noticed a little buzzing when the compressor was engaged and ran it by the dealer for them to listen to. They were not concerned, and said they could sometimes make a little noise if they were low, but since the pressures looked OK and it was cooling fine, they were not in a hurry to do anything to it. So now 5 1/2 yr later the system is low enough that it is only cooling partially.
I have not put gauges on it yet, but the bmw chat sites all say that when the system is low, it blows cold air on the driver side vents and warm air on the passenger side, which are my symptoms exactly. It's blowing high 40's on the driver's side and low 70's on the passenger side. I plan to put gauges on it tomorrow and top it up if the pressures confirm my suspicion.
So, finally, here are my questions:
1- Should I just top it up until the pressures and temperatures look right? Or should I evacuate the system and recharge to spec? I don't have a recycler, but I have gauges and a vac pump.
2- Should I introduce additional oil at this time to compensate for oil that may have been lost during the leak-down? If so, how much? I'm not willing to open up the system at this point and attempt to measure oil level in the compressor.
Thanks in advance!

JJM on Tue June 07, 2011 12:20 AM User is offline

Charging to spec would definitely be the way to go, but I admit in a pinch I will top off with pressure readings.

If you lost refrigerant, you also likely lost oil, so by all means, do add oil to the system. Best way of course is flush the system dry and add oil to spec. But since that's not the route you wish to take, check the system for any oily residue around components (including the evaporator) and fittings, that would be an indication of a major leak and significant oil loss. If the system shows no obvious signs of leaks, I would add back 2 oz of the recommended spec oil - I believe PAG-100 - to be safe. You can use an inexpensive injector like the one below:

82375 - R134a Oil Injector

I think those things push in 2 oz if I recall correctly.


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wamcneil on Tue June 07, 2011 8:17 AM User is offline

wamcneil on Tue June 07, 2011 8:20 AM User is offline


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