[Shotimes] Compressor doesn't cycle

[Kevin & Cheryl Airth]

All late model Fords have a High Pressure Relief Valve. Usually set at 450
psi. It's mounted on the compressor on the discharge side. If you lose the
electric cooling fan in stop and go traffic it's pretty common to have a big
explosion but no damage. When refrigerant is released at 450 psi it makes a
LOT of noise. But this has no connection to anything else is only used to
prevent damage/more damage to the A/C system.
.
.



> Ford doesn't use a high side switch up to 92 for sure. Older hoses are
less
> likely to leak as they are saturated with oil and are closed more. For a
> long life the R12 oil needs to be replaced as it isn't compatible with
134a.
>
>         Ken
>
> Subject: Re: [Shotimes] Compressor doesn't cycle
>
>
> > Last time I checked on Car A/C units (and many smaller home units) they
> are
> > pretty simple. There are two pressure switches that continuously open
and
> > closed based on pressure on the high and low sides of the AC system. If
> the
> > pressure in the high side is never reaching what that switch is looking
> for,
> > i.e. orrifice to large, or some other problem, you will GET cooling as
the
> > compressor runs and circulates the 134a, but the compressor is liable to
> run
> > all the time because that higher pressure is never reached.
> >
> > As was stated in the other reply to this post, there SHOULD have been
more
> to a
> > real kit. Then again, I drained and pulled vaccum on a 91 w/ a 3.8,
filled
> it
> > with 134a, and the compressor does run longer, but it DOES cycle.
> >
> > I seem to remember the low pressure side being between 30 and 50 as the
> > compressor cycled and I don't remember what the high side was (I
borrowed
> a set
> > of diagnostic / fill guages).
> >
> >
> > Sorry I couldn't help more...
> >
> >
> > Carl
> >
> >
> >
> > Quoting Kevin Galuska <whitegen1sho@hotmail.com>:
> >
> > > After having the ac system on my '91 evacuated, I charged it with
R-134a
> .
> > > The kit I bought came with a gauge and when I was through with the
> process
> > > it was read around 30 whatever the standard unit is. I ran the car for
> about
> > >
> > > 10 min afterward and was getting very nice, very cold air out of the
> vents.
> > > The only problem is that the compressor didn't seem to cycle, it just
> stayed
> > >
> > > engaged the whole time. I have checked the clutch gap and it is in
spec.
> I
> > > know most people have a problem with the system cycling to often, and
> was
> > > wondering if there is a problem with the system not cycling enough?
> > >
> > > Kevin