Hello,

I'd thought I'd share my a/c accumulator replacement experience (for cars with CCOT systems only). I've been using Chinese made accumulator (Air Products) and wondered why it's not cool enough during idling.

It turned out to be that the J tube inside the accumulator is smaller and less exact in its bending causing a restriction to compressor's suction. This causes a higher low side pressure (thus higher evaporator temp) during idling, when compressor suction is at its lowest. Satisfactory cooling is only achieved when the car is moving (higher rpm thus higher compressor suction).

Not anymore. I ordered a 4Seasons accumulator (part number 33197) made by ATCO in the US. This has much bigger J tube diameter (as seen thru the suction port). When installed the low side pressure stays below 30PSI even in hot weather (90F ambient) at idling. This has resulted in much improved evaporator cooling. Using original Volvo part would be much better I think.



Of course, certain requirements must be met at first:

1) be sure not to overcharge your system - 950gm of R134a in similar car model (there's a sticker at car front stating the recommended charge weight). Weigh the R134a tank before and after charging.

2) verify correct charge by measuring the inlet and outlet evaporator pipes temp next to firewall (i.e. evaporator superheat). The difference should not be more than 5F. Ideally it should be nearly the same. A/C must be stabilised for at least 5 mins (engine at idle) with hood and doors all open. Ambient temp must be more than 79F (do this during afternoon or similar). Blower at full speed (number 5). Recirculation door closed. This is max heat temp test.

3) condenser is cooling the charge satisfactorily (i.e. condenser sub-cooling) - difference between 20F to 50F measured at the inlet and outlet pipes of the condenser (have to go under the front bumper - measure at pipe endings).

Details about max heat temp test is available at 4Seasons website:
http://www.4s.com/Upload/Four%20Seasons/documents/Maximum_Heat_Load_Temperature_Testing.pdf


One last thing - use a contact thermometer or digital thermometer with wired sensor. Wrap blu-tek or similar substance around measuring sensor and pipe. Infrared thermometer is not accurate. Its measuring beam is bigger than the measured surface (the pipes). The laser pointer is just a guidance and not the measuring beam.


Just to share..

Amarin.