If the expansion valve is plugged or dirty you may have freon charge but you
will not get the cold air. If this is the case there is no sense in adding
more freon, and in fact you could damage hoses and other AC components by
adding more gas when the system is already charged.
To determine the freon charge and if the expansion valve is working I was
told to perform the following test:
Buy a AC refrigerant gauge (shows pressure in PSI),; its not very
expensive. Screw the gauge first onto the inlet valve closest to the
compressor. Start the car and run the AC and come out and take the reading.
This is the LOW reading and it should read no more than 40 and not less
than 15/20.
Shut the engine, disconnect the gauge and reconnect to the inlet valve
attached to the canister with the glass window (i believe that's called the
dryer). Start car and AC and take the second reading. this is the HIGH
reading and I believe should be between 200 and 300.
(My gauge highlights the acceptable range of the LOW and HIGH readings).
If the LOW reading is higher than its allowable upper range and the HIGH
reading is lower than the allowable lower limit then I was told that most
likely the expansion valve is faulty. In this case too, no sense in adding
freon without replacing valve. A good AC shop should be able to recover the
existing freon, replace the valve and recharge. This way you don't get
charged for a full freon refill.
If both the LOW and the HIGH readings are significantly below the acceptable
lower limits then you probably have low freon. I still would not add any
new freon without checking for leaks, especially because you indicate that
your AC has not lost its cold over a period of many months but has done so
"quickly and noticebly.".
Hope this helps and has not sounded more complicated than it needs to be.
Gruesbecks wrote:
> A couple of questions on my Peugeots. On the wagon the a/c is waning
> fairly quickly and noticeably. I have some freon to charge it with but
> do not know which side to charge it on. There is a connector on a line
> going into the compressor and one near the sight glass on the support
> for the grill. Which one is the one that will take the charge as I don't
> want to waste the freon I do have. Also the front needs some adjustment
> to the camber. The wheels are leaning in at the top. The car has 95,000
> some odd miles and as there is no adjustment what is the usual trouble
> areas with this front end, bushings, or struts? Thanks in advance for
> any information on this.
>
> Douglas C