I just added refrigerant to my 1995 Prelude SE (125,000 miles), and noticed
both while I was recharging and after that the compressor doesn't cycle off.
Is it normal for Honda compressors to run full-time (while the "A/C" button
is on)? I can't specifically remember if it cycled during the years I've
owned it. If it SHOULD be cycling, what would prevent it from doing so?
Using the manual "A/C" button on the console does cause the compressor to
turn off, as normal. One item to note, is that I used one of those
inexpensive "system recharge" packages from the auto parts store to add
refrigerant, which seemed to work well, but it only measures low-side
pressure. Thanks for your help.

It is normal for the A/C to cycle on and off unless the temperature is
quite high. In warm weather it typically have a higher duty cycle in
"Fresh" than "Recirk". (Opposite if using the A/C in cool weather e.g.
to defog).

The cycling is controlled by the thermostat mounted in the evaporator
housing. Specifically, the ECM controls the A/C compressor clutch relay
based on a call for cooling. The call for cooling gets to the ECM
through (in order from ECM to ground) 1.) the A/C pressure switch in one
of the refrigerant lines, 2.) The A/C thermostat in the evaporator
housing, 3.) the A/C main on/off switch on the dash and 4.) the
ventilation fan switch on the dash (separate pin grounded with fan
switch in any position except off). The A/C pressure switch is a
safety-lockout. This switch is normally on at all times.

system, have reduced cooling capacity and thus the evaporator never gets
cold enough to turn off the compressor? Measuring only the low-pressure
side is somewhat dubious. For proper charge, filling to a specific
pressure is not sufficient, the correct pressures (high and low side)
depend heavily on outside temperature *and* humidity. Since R134a is
cheap I would try removing some refrigerant (observing all relevant
environmental regulations, precautions and safeguards) and see if that
helps.


Andrew McCune wrote:

"Randolph" <trash (AT) junkmail (DOT) com> schreef in bericht
news:41453651.59AA20A4 (AT) junkmail (DOT) com...

put a manifold on it and check the temps lo side and high side normaly the
compressor go's on and off all the time
to prevent that the evaporator would not freeze..
maybe you over charged it ...
temp 134a should be +/- -10°C lo side
greetings frederik L