[s-cars] A/C Cycling on/off...
djdawson2 at aol.com
djdawson2 at aol.com
Wed Jun 30 11:40:54 PDT 2010
Again, the most suspect thing to me is the fact that you're seeing a high pressure "open." Assuming there isn't a wiring defect or a failed switch, the first thing to look for is airflow restriction... checking the items I pointed out in prior emails. Interesting is the belt slippage... as another lister pointed to this as a possibility. I'd check this as well... maybe replace the serp belt, and check to see that the tensioner isn't hosed.
If the system were actually low on charge, I don't think you'd be seeing a high pressure cut-out. You can actually put a gauge on the high side port to check your pressure. This would be the best option, as opposed to speculating. The high pressure switch has a pressure rating at which it opens (shuts the system down), and you could verify that it is functioning correctly with the gauge, confirm that it is indeed high pressure that is causing system shut-down, and verify the charge level.
Unfortunately, there isn't a low side port you can work with unless you have an adapter. Search the archives, some folks have provided info on what to buy. However, there will be little value to checking your low side in this case.
If I were you, and I didn't have access to a gauge, I'd do the common sense stuff first... check/replace the serp belt and look at the tensioner, take the car to the car wash and blow out the radiator and condenser to try and clear any build-up of bugs and debris. Spray from inside the engine compartment towards the front of the car. I'd also take a look at the fins of the rad and condenser to make sure they're not folded over.
It doesn't take a huge restriction in airflow to increase the system pressure dramatically. This isn't good, especially on old cars. High pressure cut-out is usually set at around 400psi. In an old car with old hoses, this can lead to a hose failure if it happens frequently... compounding your problems.
Dave
-----Original Message-----
From: Andrew B <andrew.sb at gmail.com>
To: Andrew Beckert <abeckert at gmail.com>
Cc: djdawson2 at aol.com; s-car-list at audifans.com
Sent: Wed, Jun 30, 2010 12:03 pm
Subject: Re: [s-cars] A/C Cycling on/off...
Looking over the codes I previously gathered when I had this problem
the other time, I see 08, 11, 13 and 15.7 (sporadic blocks on vents),
and 29.4, (Belt slip detection, Hard, sporadic) and finally 22.3, "A/C
Refrigerant High Pressure Switch, F118, Sporadic open. Via the 12V
guide.
I'll check these again tonight, as I'm uncertain if they're the same,
but if it is indeed the high pressure switch, what should be my next
course of investigation? Replace the switch? Refill? Can I check
the pressure to find out if I've lost enough refrigerant for a
recharge?
Thanks for the help so far,
-Andrew
On Wed, Jun 30, 2010 at 1:46 PM, Andrew Beckert <abeckert at gmail.com> wrote:
> Overcharging will also result in the high pressure switch kicking off the
> compressor in traffic and other heat soak situations. These were the
> symptoms I experienced, so make sure whoever evacuates and recharges your
> system knows exactly what they are doing.
>
> Andrew
>
> On Wed, Jun 30, 2010 at 1:26 PM, <djdawson2 at aol.com> wrote:
>>
>> Low refrigerant will usually keep the compressor for engaging for anything
>> more than a few seconds. A system that runs and kicks off is typically
>> suffering from a lack of airflow, resulting in high system pressure cut-off.
>> This could be the aux fan, a weak fan clutch, a radiator and/or condenser
>> packed full of bugs and debris, or bent fins on either or both the rad and
>> condenser.
>>
>> If it cuts out routinely, I would be trying to determine if it is the high
>> pressure switch that is turning things off. Based on what you've said about
>> traffic and heat, it seems to me that this is most likely the case.
>>
>> Dave
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> -----Original Message-----
>> From: Andrew B <andrew.sb at gmail.com>
>> To: djdawson2 at aol.com
>> Cc: s-car-list at audifans.com
>> Sent: Wed, Jun 30, 2010 7:45 am
>> Subject: Re: [s-cars] A/C Cycling on/off...
>>
>>
>> Well, I checked my Aux fan this morning and it does indeed turn on
>>
>> with the AC. I have heard before that low refrigerant could cause the
>>
>> problem, on QW, but it was more in passing than a "Here's your
>>
>> answer". I have heard the afterrun pump turn on before, but not
>>
>> recently. I'll keep an ear out for it in the future.
>>
>>
>>
>> I also checked the codes, and the only thing I really found was a
>>
>> "Belt slip, Hard, sporadic" that would indicate any compressor issue.
>>
>> Maybe I'll try and get over to an AC shop for a check and refill...
>>
>>
>>
>> On Tue, Jun 29, 2010 at 4:28 PM, <djdawson2 at aol.com> wrote:
>>
>> > Keeping the CC cluster out of the equation for now.... I would suggest
>> > that
>>
>> > if your A/C is cutting out while in traffic or going slow, that your aux
>> > fan
>>
>> > is probably failing to operate. This means inadequate airflow,
>> > resulting in
>>
>> > high system pressure, and eventually cut-out due to high pressure.
>>
>> >
>>
>> > I would check operation of you aux fan (with A/C on) as a starting
>> > point.
>>
>> >
>>
>> > Dave
>>
>> >
>>
>> >
>>
>> >
>>
>> > -----Original Message-----
>>
>> > From: Andrew B <andrew.sb at gmail.com>
>>
>> > To: s-car-list at audifans.com
>>
>> > Sent: Tue, Jun 29, 2010 1:41 pm
>>
>> > Subject: [s-cars] A/C Cycling on/off...
>>
>> >
>>
>> > The other day I was driving my 95.5 S6A from Boston to CT, and shortly
>>
>> >
>>
>> >
>>
>> > into the drive I encountered some heavy traffic. As I shuffled along,
>>
>> >
>>
>> >
>>
>> > the A/C kept cutting out. This has happened before, again in heavy
>>
>> >
>>
>> >
>>
>> > traffic, and on a hot day. Later, after the traffic finally
>>
>> >
>>
>> >
>>
>> > dissipated, the A/C nor Recirc buttons/icons would stay lit, no matter
>>
>> >
>>
>> >
>>
>> > whether I stopped and shut the car off or not.
>>
>> >
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>> >
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>> >
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>> > When I got to my destination, I left the car until the next day, when
>>
>> >
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>> >
>>
>> > I started it up and the A/C worked fine. A quick drive that evening
>>
>> >
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>> >
>>
>> > with the AC on was fine. Finally, on the trip back to boston (with no
>>
>> >
>>
>> >
>>
>> > traffic and slightly ~5* cooler temps) the AC worked the whole way
>>
>> >
>>
>> >
>>
>> > home with no incident.
>>
>> >
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>> >
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>> >
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>> >
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>> >
>>
>> > Also, late in both drives, my CC cluster became hard to operate.
>>
>> >
>>
>> >
>>
>> > Buttons near the top would not function, but lower ones worked OK.
>>
>> >
>>
>> >
>>
>> > This doesn't seem completely related to the traffic problem, as I
>>
>> >
>>
>> >
>>
>> > could press the snowflake button, but it turned right off.
>>
>> >
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>> >
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>> >
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>> >
>>
>> > Any ideas? There didn't appear to be any overheating issues as the
>>
>> >
>>
>> >
>>
>> > idiot light did not come on and the temperature never climbed off the
>>
>> >
>>
>> >
>>
>> > fat line, although is did creep to the hot side of it. Could my CC
>>
>> >
>>
>> >
>>
>> > head be overheating? Compressor clutch? There doesn't seem to be any
>>
>> >
>>
>> >
>>
>> > additional noise although the car does drive somewhat more sluggish
>>
>> >
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>> >
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>> > with the AC on.
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>> >
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>> >
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>> > Would love to find a solution for this...the one place I want AC the
>>
>> >
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>> >
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>> > most is where it habitually cuts out...
>>
>> >
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>> >
>>
>> > -Andrew
>>
>> >
>>
>> >
>>
>> > _______________________________________________
>>
>> >
>>
>> >
>>
>> > S-CAR-List mailing list
>>
>> >
>>
>> >
>>
>> > http://audifans.com/mailman/listinfo/s-car-list
>>
>> >
>>
>> >
>>
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>>
>> >
>>
>> >
>>
>> >
>>
>>
>>
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