A/C Woes

[tommyr]

2001 XJ 4.0L Auto trans, 242 xfer case. Outside temp in somewhat humid Chicago is about 80 degrees

Have a strange problem. A/C has been out for quite some time. Decided to look into it. Replaced accumulator and line with the orifice tube in it. Measured the oil in old accumulator. Nasty black looking. Added new oil to new Acc. Cut open the old orifice line. Orifice plugged pretty well with black powdery stuff.
Evacuated system for 1 hour, charged it up with 2 cans (~24oz), of 134a. Here's where it gets interesting. without the aux (electric) fan on, system sits at 28 low/225 high. Low side seems low. With engine warmed up and aux fan on, 24 low/175 high and will cycle because low cut off is right around 25. As engine gets warmer, low stays about 24/ high drops to about 150. Continues to cycle on low cut off. Center outlet temp about 40 degrees on recirc and high fan. About where it should be.

Now, at first glance I would think not enough 134a (both pressures too low), and upon looking at other cans of 134 I had, I noticed one brand new can was completely empty so figured maybe the 2 cans I used were a little light. So I added about a half can. NO DIFFERENCE in pressures with more added. So, system not low on refrigerant and is blowing cold air. Trouble is with the low side that low, any throttle and it will cycle due to low side being too low.

Any ideas? I've spent a lot of time looking online and couldn't find any real information on my symptoms.

 

[andjones]

I would suspect your orifice is partially plugged, possibly with the mentioned black powdery stuff. Evacuating a system does not remove any foreign material it only removes the air and moisture. The orifice controls the amount of liquid refrigerant (high side) that evaporates into the evaporator (low side). The compressor appears to be sucking up refrigerant faster than the orifice can supply it.

 

[tommyr]

Andjones, thanks for getting back to me. I wouldn't imagine the orifice being instantly clogged up, but it got me thinking. When I cut the line open, the orifice color was purple. My replacement 4 seasons hose did not specify, but another aftermarket line (GPD brand) said green orifice built in. Green is .052, Purple is .0605. Hmm. bigger would create less of a restriction. I called 4 seasons to ask what orifice was in their line. Of course, they didn't know. Without sawing it apart, I can't tell either. My suspicion is that its green, probably like the other manufacturer. OE lines are still available, and the parts list only shows 1 number for the LH drive 4.0 . OEM may be the way to go.

 

[RCP Phx]

You are going to need to take to a good ac shop anyway, they could do a flush on the whole system!