[DML] Re: A/C Problems (necessarily long)

["Harold McElraft" <hmcelraft@xxxxxxx>]

Here is the clue to your problem -

"The system held vacuum for a long time (about -29) so there don't 
appear to be any leaks. Then as soon as I started the car, with a 
completely empty and vacuumed down system, the compressor was 
already cycled on, non stop! We went ahead and recharged with 2.2 
lbs of fresh R-12, with no change in operation whatsoever."

There is a direct connect to the clutch via the switch some how not 
through the low-pressure cycling switch. The compressor should not 
have come on here. If you trace the wire you will find a short or 
probably an incorrect mod or reinstall.

The clutch has been taken out of the low-pressure circuit.

Harold McElraft - 3354


--- In dmcnews@xxxxxxxxxxxxxxx, Jake Kamphoefner <jakekamp@xxxx> 
wrote:
> All,
>  
> A/C experts, please read!  I've got a really strange issue with my 
air conditioner that I'd like to properly diagnose before I go 
replacing more parts.  This is a long post, but I wanted to include 
all the relevant info:
>  
> Since I bought 1063, the A/C has always "worked", but the air is 
never as cool as it should be.  I've also noticed excessive sweating 
of the evaporator core, even after cleaning the drain out with 
compressed air.  The most peculiar thing: my compressor never cycles 
off.  As soon as I hit the mode switch to any A/C position, both my 
cooling fans and my compressor turn on, and *never* turn off unless 
I turn the mode switch to vent or above.  This includes, idling, on 
the highway, cool days, hot days, etc.
>  
> I've got records for the car back to 1983.  The work was all done 
by Steger and includes a new NOS compressor (about 5 years ago) with 
all new A/C hoses.  As far as I can tell, the accumulator bottle, 
evaporator, and condenser are all stock, but appear in excellent 
condition.
>  
> I stopped using the A/C because I didn't want to overwork the 
compressor or those circuits, but here's what I've tried to do to 
fix it in chronological order:
>  
> 1.  I sniffed another bottle of R-12 in the system, after someone 
suggested I might be low on freon.  No change.
>  
> 2.  I put gages on it and found that my low side pressure was 
dipping into the low teens, while my high side was blowing up way 
over 300 when the car was revved.  The low pressure switch never 
kicked off the compressor, so I pulled the plug off the low pressure 
switch and everything stops as it should.  So I replaced the low 
pressure switch.  No change, everything on.  Then I tried adjusting 
the switch to the extremes (both directions) with no change.  I even 
switched it out with a known good switch with no change.  Rob Grady 
suggested that I may have a restriction in the system and suggested 
I replace the accumulator bottle and orifice tube.  So....
>  
> 3.  I bought a new bottle and orifice tube.  I evacuated the 
system replaced the bottle and orifice tube without damaging any 
fittings (thank God this car was from California...).  The old 
orifice tube had a few particles of black gunk on it, but was 
actually very clean overall.  Then I vacuumed it all down for a long 
time.  The system held vacuum for a long time (about -29) so there 
don't appear to be any leaks.  Then as soon as I started the car, 
with a completely empty and vacuumed down system, the compressor was 
already cycled on, non stop!  We went ahead and recharged with 2.2 
lbs of fresh R-12, with no change in operation whatsoever.  The 
compressor is still constantly on and the temperature out of my 
vents was only about 59 or 60 degrees.  Never any colder.
>  
> 4.  Then we suspected an electrical problem.  I got out the wiring 
diagram and found that my wiring appears to be all stock, with no 
modifications.  Pulling fuse 10 shuts it all off as it should (we 
tried this because we thought we might be getting some kind of 
feedback from the fuse 5 circuit).  We also tried replacing the 
diode in the electrical compartment (the one between pink and 
black/orange, I think?) shown on the wiring diagram with no change.  
However, this car has never been fitted with a high pressure switch, 
but it is my understanding that a missing high pressure switch 
shouldn't cause this weird problem.
>  
> The car makes all the right sounds (except cycling):  I hear 
the "woosh" of freon through the evaporator core, the bottle sweats, 
the evaporator core is cold and the drain drains, the compressor is 
quiet and the clutch for it engages smoothly.  My blower motor is a 
quiet NOS that blows a high volume of air, and I have no melting of 
any fuses in the electrical compartment.  Also, the mode switch 
appears to be in excellent condition, and I don't believe there are 
any leaks in vacuum; all air is directed quickly to the right 
spots,  I've also verified a tight fit of the foam on the back of 
the evaporator core.  The condenser is clean and still has almost 
all of it's paint.  My cooling fans work great and flow in the 
proper direction.  I've also verified that my heater core valve is 
closed.
>  
> Ok, so do you have any suggestions for me?  I'm ready to do or buy 
anything at this point to get the thing to work right.  Does this 
sound like there is still a restriction some where?  Could I have 
some internal compressor damage?  Any help you can give is greatly 
appreciated.  Right now I'm leaning toward an evaporator 
replacement, but I hear it's an awful job.  Maybe I can hire Dave 
Strangand to put my car back together after replacing the evap.  :-)
>  
> Thanks a lot!
>  
> Jake Kamphoefner
> 1063 in Southern IL
> 
> 
> 
> [Non-text portions of this message have been removed]






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