[DML] Re: verifying a/c charge amount

["Walter Coe" <Whalt@xxxx>]

David T,

> 2) Using a sonic device to detect supercooled droplets in the suction
> line.

I never knew that such a device existed; though, I have heard of a similar
device that detects vapor bubbles. Can you recommend a source for learning
more about the sonic devices?

> 3) Filling to the sight glass (If a sight glass is even on the
> system).

Not a chance in the DeLorean even if you installed an aftermarket sight
glass. In accumulator/orifice tube systems, there will always be bubbles in
the liquid line.

> 4) The least precise and most widely used method, filling till the
> compressor runs or at least to a suction pressure corresponding to
> about 34 degrees F for the refrigerent being used.

This sounds like my best bet considering my resources at hand.

I started this thread because I'm installing a variable orifice valve (VOV)
in place of the OEM fixed orifice tube. The fixed tube is a crude
compromise between what it needs to be at idle vs. highway speeds. By
upgrading to a VOV, the orifice automatically adjusts to the optimum size
for the pressure of the refrigerant. This translates to cooler evaporator
temperatures at idle, less compressor cycling, longer compressor life and
better fuel economy. I have done quite a bit of reading on it, and there
apparently are no disadvantages to using a VOV in either an R-12 or R-134a
system. But of course I'm only reading the manufacture's hype.

My strategy is to get the system working with the VOV with an accurately
measured refrigerant charge. Then closely monitor the system's pressures &
temperatures and use that as a benchmark for future diagnostics.

Walt