OK, I've gotten a better handle on this (better doesn't mean a whole
lot in my case, though).

Here are my stats:

Suction line - 63 psi, line temp is 53.5 deg F
Liquid line - 215 psi, line temp is 163 deg F.
Ambient air at bottom of condenser is 81 deg. F.

(This is after adding about 2 lbs of R22.)

If I get it, the subcool is now about 15 deg, and the superheat is
about 60 deg. But, I don't know how this relates to what I need. How
do I figure that out?


BTW, my system is a 5 ton unit, which is oversized for my house, but
that's what the idiot installed 11 years ago. I have been told that a
3.5 ton unit would be better for my place. I plan on replacing the
whole thing as soon as the money's there; preferably with a
ground-source heat pump.

Joe

On Sat, 09 May 2009 18:30:25 -0400, Joe wrote:

I have a small leak in my evaporator. So, here comes the cooling
season again, and until I have the money to get the system repaired, I
need to add a charge. I've got the gauges hooked up, and measured the
ambient temperature at 82 deg F.

I remember that I used to just subtract x deg. from the ambient, and
add refrigerant until I reached that value on the low-side gauge.
However, I don't remember what that value is. IIRC, it was 35 or 40,
but the synapses don't fire like they used to.

Can anyone help me out here? I fail to understand the
superheat/subcool stuff, but the rule-of-thumb has served me well in
the past.

Joe