A/C problems

>> I wonder what a spray can of brake cleaner might do to it. It comes
>> with a tiny little spray tube that could squirt right into that gap.
>
> Go in from the front of the pulley side. The "clutch" is a ferrous plate
> that is pulled in against another metal plate by the electromagnet - kind of
> like a solenoid plunger. The plates have some grooves in them that pack up
> with grease/oil/chips and oil will also gum up on the sides of the cup.
> Your brake fliud or carb cleaner will cut that grease. I've also had pretty
> good luck using Simple Green in there. Just soak it good and try to cycle
> the clutch several times while it's still dripping. I usually pull the
> solenoid wire and use a jumper to cylce mine several times, then hit it with
> as much pressure as I can from a hose to get it cleaneded out.

Mine is a mitsubishi, not a jeep, so the clutch is probably different.
I do tip my hat to the poster that suggested the water or air hose. I'll
give it a good test today, but it stayed on Friday from the time I left
work to the time I got home and then some, including some on purpose
cycling. I still want to use some cleaner followed by compressed air.

As they say YMMV, but chances are the clutch is just gunked up.
If I pull the connector in the TXD, the engine slows down and
the fans turns off and all comes back on when I reconnect it,
so that part must be working.

I charged it "blind" using only an AC thermometer stuck in the vent.
When it hit 43 degrees, I gave it another minute or two of gas and then
disconnected, after turning off the motor, of course. Now I have gauges
for PAG oil. My other R134a gauge has ester oil in it.

On 7/5/2011 05:28, PeterD wrote:
> On 7/4/2011 11:14 PM, Scott in Baltimore wrote:
>> lid wrote:
>>> My air conditioner has gone flakey on me but the symptoms aren't
>>> consistent so I haven't been able to get a diagnosis. It blows hot
>>> and cold.
>>>
>>> Usually, when I first turn it on, it blows cold.... for awhile, maybe
>>> 10-15 minutes (or more or less).... then the cold goes away and it
>>> feels lmore ike outside air blown by the vent fan.
>>> But if I leave the control on "A/C, it might start blowing cold air
>>> again after another 10-15 minutes. When I'm driving, I can't hear
>>> anything turning on/off under the hood nor can I feel anything.
>>>
>>> Jiffy Lube guy (who also services A/C) couldn't make it act up when he
>>> checked it and he guessed it might be hoses freezing up. The
>>> dealership couldn't make it act up either and they guessed it would be
>>> the compressor clutch, so best to replace the whole compressor (for
>>> about $1000). Both Jiffy and dealer told me to bring it back in when
>>> it's not working. But my crystal ball stopped working years ago and I
>>> never KNOW when it's going to work and when it's not. It both comes
>>> and goes with no warning and no regularity.
>>>
>>> Anybody want to take a stab at what the problem might be? And better
>>> yet, an inexpensive way to nurse it along through the summer?
>>>
>>> Rick
>>> HeBeJeepN
>>> '99 XJ Sport, Selec-Trac, Trac-Lok
>>
>> I'm wondering myself. My car does this exact thing. Blows nice and cold
>> for 15 to 20 minutes, then the compressor won't click. The car will turn
>> on the fans and speed up the engine, but no click and no compression.
>
> A marginal refrigerant level (low, but just above the low pressure
> cutoff) will cause this to happen. The system, when cold has less
> pressure overall, and the low pressure switch then cuts off. After the
> system warms up (say it sits for a while) it then starts up again.
>

My experience with low refrigerant has been that the compressor clutch
cycles on and off even with the unit set on max cool. Confirmed by FSM.