The reason that I thought that the compressor is bad is: At Idle the
LO side
is about 24 Psi ( or something, it matched a listing in a book) The HI
side
would not make 100 Psi (75 ?? don't remember).
Both pressures are low. Compressor _could_ cause this, but it sounds
undercharged.
As the RPM is increased 3 to
4 K the HI side would jump up to over 200 Psi.
Still a bit low. I push 300 psi when charging with my test
refrigerant on a hot day. But what I'm really doing is matching
the _temperature_ scale on the R12 gauge to the temperature of
the high-side fitting (while trying to keep it under 300 psi,
while making sure the low-side hovers above freezing, engine at
2000 rpm). A dead compressor couldn't do this.
The LO side would be 15 to 20 inches vacuum.
Also too low. (Translation: the compressor is being too effective
for current conditions.) Undercharged? Does not sound like a
dead compressor to me.
What should I look for?
This is still R12? If the sight glass is frothy the system is
definitely undercharged, and pressures _will_ be low.
Are you _sure_ that there's anything more wrong than it's just
undercharged? The systems (all of them) do leak a little, which
is why R12 systems were built to hold an excess charge. Got them
past the warrantee period before they stopped cooling.
Most of our cars require charging annually now. But the test
refrigerant is both cheap and benign.
-- Jim
