HELP! A/C Compressor Won't Stop!!!!

Little Background...

1995 1.5L Civic DX 4-dr, purchased in November. Finally gotten around
to repair the A/C Compressor this past weekend (money issues). The
"original?" A/C Compressor housing was cracked and and I could
literally see in.

Anyhow we removed the old one and plopped in a refurbished one (yes I
put a new dryer in as well). We flushed it with the flushing liquid
(and a stupid $69 bottle and hose to flush it out with! grrr.), and did
what the Chilton manual said to do. Turn the A/C on Max Cool and A/C on
and start the car and we began to fill the system.

Here is my dilemma.

1) now the that coolant is charged (high side reading 225 psi, low side
about 40 psi) and system cooling nicely, I go to shut off the A/C from
the dashboard control - the compressor clutch is still engaged!
2) pressure builds to over 400 psi (yikes)! I have to quickly shut the
car off, or turn the A/C Blower back on to get the condenser fan to
turn on and lower the pressure.
....
<sigh>
....
3) I turn the car off, and start it up again -- the clutch is
disengaged for a second while the car goes to idle speed, then it
engages. I took the two relays (condenser fan relay and compressor
clutch relay) apart so I could view them in action. The relays come on
(and off) when the compressor comes on and off.
4) the compressor relay seems to be controlled by the ECM A15(?) line,
which makes sense in the start up of the A/C after the engine has come
on.
5) the compressor will "compress" even if the following conditions
exist
- low pressure switch open (system empty) or closed (system charged
with new 134a)
- A/C button is off at engine start
- Blower is off at engine start
- A/C button is turned off while engine running
- Blower if turned off while engine running

The thermal overload seems to be ok.
The little diode "seems" to be ok - I haven't fully verified, but I
believe that is more crucial for the condenser fan
The compressor will stop if I disconnect the red wire connector to it.
The red wire reads 0v while engine is started, 12v 1 or 2 sec after
engine starts

The only way I could prevent the compressor from running is to remove
the 20A fuse in the U/H F/B for the Condenser fan/Compressor clutch.

--------------

I wonder if this is how the first compressor housing was cracked and
disintegrated when I bought the car - the compressor started to run and
build up pressure without the condenser fan and built up pressure to
past breakage...

Do I have a bad ECM module? Is there a bad sensor? What do I check to
get it to cycle properly (which it won't) and shut off when I turn the
dashboard A/C controls off?

The A/C light comes on and off when I press the dashboard button - but
it seems to have no effect on the Compressor Clutch.

Desperately seeking advice.

Thanks in advance!

~lum

 

Is it possible the previous owner hot wired the compressor? I would be
looking for a jumper wire in one of the fuse/relay boxes. I would also
look at the relays in the electrial box under the hood.... Test those
relays. Good luck!

 

Did you remember to pump all the air out of the system using a vacuum pump?
I ask because you didn't mention that part. Some people try to purge the
air using refrigerant, but it doesn't really work. Air is compressible but
does not liquify and interferes with the refrigeration process.

It sounds as if you have an electrical fault, such as the compressor being
hot wired, a relay being stuck, or maybe even a bad computer. How much of a
wiring diagram does that Chilton's have in it?

Earle