Ah, useful data
I was running the engine with the manifold on and the service line feeding goo.
I have a chart that lists both high and low side at specific temp in f and
C. The system was showing pressures consistent with the chart, but the charge
was low. The IR probe was not used to measure at those places specified.
I have not tried the rest pressure test. Figured it would show what it would
but that would not be indicative of useful data. I do know how much goo was
injected, as I have evacuated the system, such that there should be nothing
left inside prior to beginning the charging. I should be shy 24oz.
I did take the car out for some short (under 10 mile) trips and was pretty
impressed with cabin temps and cooling.
> On Jul 15, 2017, at 12:26 PM, fmiser via Mercedes <email@example.com>
>> clay wrote:
>> I evacuated the system once more (it had been tested overnight)
>> and did a refill. Well, sort of. It calls for 3.3# of R12.
>> There is a pressure/temperature chart that gives pressures based
>> on outside temp. Using that, I reached the required pressures,
>> but am short on volume?
> At rest pressure CANNOT be used to figure out how much is in the
> system. Once there is about 20% change, the at-rest pressure will
> match the chart. It won't change until thy system is
> over-charged. That's the nature of gas. (not gasoline/petrol)
> With the compressor running, looking at the low side pressure can
> give a pretty good clue as to the change. The high side doesn't
> tell much about charge.
> Weight is the most consistent way to determine change.
> That's hard to do on an partly-changed system 'cause it's hard to
> weigh what is inside. Without a machine to remove it all, (and
> scrub it clean and weigh it before putting it back in) the only
> way I know is to monitor temperatures in the evaporator. Checking
> inlet and outlet temperatures can be enough. A no-contact IR
> thermometer is handy - but remember most of those are calibrated
> for black, not aluminum, surface.
> Out of the compressor should be hot. Out of the condenser should
> be quite warm. After the expansion valve and inlet to the
> evaporator should be cold. Out of the evaporator should be about
> the same or a bit colder.
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