2006 Volvo V50. A/C was discharged when I got the car. This spring, I replaced the service valves, pulled vacuum, which held at 29psi for 30 minutes, and recharged by weight. Cooling was good until yesterday. Compressor is short-cycling. Low and high side read ~50psi (70F ambient), a little more when the compressor kicks on. I was expecting the problem to be a slow leak that discharged refrigerant, but these readings seem to point elsewhere. Any suggestions as to where to look next?
In reply to 02Pilot :
Low refrigerant or dead compressor. Possibly a bad low-side or high-side pressure switch.
You should have 100+ psi with the compressor not running so I'm leaning toward low on refrigerant.
Toyman! said:In reply to 02Pilot :
Low refrigerant or dead compressor. Possibly a bad low-side or high-side pressure switch.
You should have 100+ psi with the compressor not running so I'm leaning toward low on refrigerant.
That's not the information I've found, but then I know almost nothing. This is the chart I'm relying on for pressures:
In reply to 02Pilot :
Toyman said 100 psi with the compressor *not* running.
That chart is for use when the compressor is running. When it's off, the low and high side pressures quickly equalize.
My experience is the same as Toyman's, around 100psi on both sides with the compressor off is a good charge of R134a, but I'm sure it varies with temperature a bit.
AngryCorvair (Forum Supporter) said:In reply to 02Pilot :
Toyman said 100 psi with the compressor *not* running.
Correct.
Your chart is assuming the compressor is running 100% of the time with the system set to max cool, the fan on high, and the windows rolled up. If you are short cycling with 50psi on both sides, there is a 98% chance you are low on refrigerant.
OK, got it. This is why I asked - my ignorance on this subject is considerable. Sounds like I'm going to be tossing in some refrigerant to get me through the next six weeks or so of hot weather, then I'll tackle a proper repair over the winter or in the spring. Thanks folks.
In reply to 02Pilot :
If you do some studying, you can probably find the leak. Frequently they happen at joints and will show up as a little oily residue around the fittings. The front of the compressor will show it as well if the front seal is leaking.
Also, older vehicles frequently already have UV dye in them so a pass with a black light may show where it's leaking as well.
In reply to 02Pilot :
Sorry i was so short with my reply. i didn't mean it to sound as harsh as it does. i was going to follow up with what others said about that chart, but my boss walked up and i hit send without completing my thought.
In reply to Toyman! :
I'm given to understand that the condensers are the problem child in the Volvo system, so I'll start my investigation there when the time comes. At least the common failure isn't the evaporator like on my BMW (I farmed out that repair). Unfortunately, I don't have time to rip it apart at this point, so quick and dirty is going to be the name of the game for now.
In reply to AngryCorvair :
No worries. I didn't take it as anything but a simple corrective statement.
For those desperate for closure, I put one 340g can in (about 50% of the capacity of the system), compressor settled down, pressures came back up, and the air is cold once more. Thanks again.
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