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Question on wiring of 97 A/C pressure switch



 
 
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  #1  
Old July 25th 05, 04:10 AM
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Default Question on wiring of 97 A/C pressure switch

A few weeks ago I posted a problem with a family members 97 V6 A/C not
working. A poster suggested removing the A/C pressure switch and
hitting it a few times because sometimes it can get stuck. Well I tried
that and it did not work, but I noticed that on the switch there are 2
electrical pins, but the wiring harness connection has 3 wires on it.
When I tried to jump the switch, I got a big spark and the car almost
died. I thought I jumped the correct pins. Does anyone know how to jump
out the switch? And what is the 3rd wire for when apparantly it's not
connected to anything.

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  #2  
Old July 25th 05, 05:49 AM
Jim Warman
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Stop now, before you kill anything. Either take it to someone qualified or
spend some time learning about the system.... this WILL involve PURCHASING
manuals and READING them. If it was all that f*cking simple, do you think
I'd have a job?

Don't mind me, I'm just feeling "verbose".

Remove and hit it a few times.... it didn't work with my hot water tank....
didn't work with the TV..... didn't work with the toaster (though the flames
were kinda nifty)... and it didn't work with the leak in that rear tire.....
I feel qualified to say that hitting broken things may only make them
brokener (is that a word?).

On the off chance that giving a failed part a whack will make it work again
(and it does happen), you will find that you will soon have to give it
another whack. After that, the whacks will increase in frequency and the
part will finally fail catastrophically.... usually taking out some very
expensive, very innocent parts in the process. But that's OK.... I fix this
stuff for a living and, if you ignore my advice, someones profit margin will
benefit.


> wrote in message
oups.com...
> A few weeks ago I posted a problem with a family members 97 V6 A/C not
> working. A poster suggested removing the A/C pressure switch and
> hitting it a few times because sometimes it can get stuck. Well I tried
> that and it did not work, but I noticed that on the switch there are 2
> electrical pins, but the wiring harness connection has 3 wires on it.
> When I tried to jump the switch, I got a big spark and the car almost
> died. I thought I jumped the correct pins. Does anyone know how to jump
> out the switch? And what is the 3rd wire for when apparantly it's not
> connected to anything.
>



  #3  
Old July 25th 05, 06:37 AM
Richard
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What I said was: "You do not have to evacuate the system. The instructions
I gave are from
Ford's service manual. My valve was sticking and a light tap would sometimes
allow the circuit to close and thus engage the compressor clutch."

Also notice I said "light tap" . Once I identified the source of problem I
replaced the switch. It's not an expensive part.
--
Richard

'94 GT 'vert
Under Drive Pulleys
Transgo HD2 Reprogramming Kit
High Stall Torque Converter
4:10 Gears
Gripp Sub Frame Connectors (welded)
FRPP Aluminum Drive shaft
FRPP M5400-A Suspension
Laser Red

> wrote in message
oups.com...
> A few weeks ago I posted a problem with a family members 97 V6 A/C not
> working. A poster suggested removing the A/C pressure switch and
> hitting it a few times because sometimes it can get stuck. Well I tried
> that and it did not work, but I noticed that on the switch there are 2
> electrical pins, but the wiring harness connection has 3 wires on it.
> When I tried to jump the switch, I got a big spark and the car almost
> died. I thought I jumped the correct pins. Does anyone know how to jump
> out the switch? And what is the 3rd wire for when apparantly it's not
> connected to anything.
>



  #4  
Old July 25th 05, 11:39 AM
Backyard Mechanic
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wrote in news:1122261014.970907.175520
@o13g2000cwo.googlegroups.com:

> A few weeks ago I posted a problem with a family members 97 V6 A/C not
> working. A poster suggested removing the A/C pressure switch and
> hitting it a few times because sometimes it can get stuck. Well I tried
> that and it did not work, but I noticed that on the switch there are 2
> electrical pins, but the wiring harness connection has 3 wires on it.
> When I tried to jump the switch, I got a big spark and the car almost
> died. I thought I jumped the correct pins. Does anyone know how to jump
> out the switch? And what is the 3rd wire for when apparantly it's not
> connected to anything.
>
>


It WOULD be a pretty good spark and the car MIGHT 'almost die' when the
compressor clutch engages... or it might seem that way.

But I assume you jumpered between the switch connectors, not the switch
itself.
Whatever... the fact it had voltage means either the switch is bad or the
system is low on freon, which should rule out any problem in the controls

Install the jumper in the connetcor while the A/C is off then switch it
on

IF the engine DOES indeed bog down seriously then you may well have a bad
compressor. OR it's overfilled (see below) Or one of a few other problems
requiring someone really familiar with the systems to look at it.

If the engine merely drops a little under load.. check at the firewall,
to see that the line going from the condenser (fonrt of radiator) to the
evaporator (inside heater box) gets cold, if it doesnt within a few
seconds, stop immediately. You either need freon or there are other
serious problems.
If it does get cold replace the switch.
- - - - - - - - - -

The third wire is likely there as a convenient junction point... not
unusual.
- - - - -
My question is how a "mechanic" can determine that the system isnt low on
refrigerant if he didnt know for sure that it was an electrical problem
or not.

The system HAS to be running to test for adequate refrigerant. There is,
otherwise, NO static pressure test that will determine that.

If you have 2 oz or 2 lbs of freon in there the pressure will be the same
unless it is running.

HOWEVER!!!! If he 'knows' it has enough because he FORCED it into the
system... then you MAY ruin the compressor becuase it is overfilled!

Which WOULD account for the engine laboring mightily when you switch it
on.

Which, in turn, is why I got my certification and do my OWN freakin A/C
service - House and car!
Half those guys cant even explain what terms like superheat and sub-
cooling mean in practical terms
  #5  
Old July 25th 05, 07:00 PM
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For the record, I know for sure the compressor did not kick on when I
jumped the switch. And the piece of wire that I jumped it with ( 16
guage stranded) got hot. It's like as if I shorted out the battery,
thats how big the spark is. This car did have some work done on it
recently ( again, this is not my car, it belongs to my brother-in-law).
So it's possible the wiring got screwed up.
But even with the big spark, I would expect a fuse to blow. This is why
I'm a bit stumped.

  #6  
Old July 27th 05, 12:45 AM
Armon Tanzerian
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Which switch are you messing with ?

There's the CYCLING switch on top of the accumulator, and then there's the
High pressure switch which is in the high side line, towards the front of
the car, by the radiator.

The one you can "jump" to get the compressor going, to install freon, or
just test what's going on is the one with ONLY 2 wires back by the firewall,
on the accum.

You can also go a different route, and use a test lamp to check for 12v on
both sides of the switch. If it is only on one side, then either the switch
is broken, or it is WORKING, and the pressure is too low to engage it.


> wrote in message
oups.com...
> For the record, I know for sure the compressor did not kick on when I
> jumped the switch. And the piece of wire that I jumped it with ( 16
> guage stranded) got hot. It's like as if I shorted out the battery,
> thats how big the spark is. This car did have some work done on it
> recently ( again, this is not my car, it belongs to my brother-in-law).
> So it's possible the wiring got screwed up.
> But even with the big spark, I would expect a fuse to blow. This is why
> I'm a bit stumped.
>



 




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