Rear A/C Question...

[MonTex]

I discovered that my van (with rear A/C) has previously been converted to R-134A <sniff>. That said, my van's A/C turns on, and the compressor clutch engages OK. So, I set-out to re-charge the A/C after discovering that it was just barely cooling. I have a set of gauges that initially read that the system was 'low.' I vacuumed/evacuated the system, all held vacuum all night. Re-charged with two cans of R-134A into the system, watching my A/C guages and the thermometer in the center air vent, the system slowly took its charge. High-side settled at 220 psi, low side at about 35. Cooling efficiency was below par, and would only cool to about 60-Deg. F. out of the front vents. The rear A/C was ON, the fan continued to blow only ambient temperature air while the front was cooling somewhat OK (but at only 60 F). Initially, I figure that my compressor is compromised and in need of replacement (and parhaps some other A/C parts. My system took only about 1/2 normal freon quantity for high-side pressure to get to 210~230...with low-side pressure at about 35. I did not use any freon that had sealant in it, and do not know if it had any sealant installed prior to my owning the van.

My reach-out to the forum members concerns the fact that my rear A/C is not blowing 'cool' air as the front vents are. I opened the rear A/C access panel - the fan was blowing, yet no cool air coming from the vents - the air was ambient warm. In this rear access panel, I saw the "expansion valve" and what looks like a 'high' pressure port. Consulting the A/C schematic in my Toyota manual, I do not see this 'high' side pressure port, nor do I see any troubleshooting verbiage pertaining to the rear A/C not blowing cool air.

I could guess that the expansion valve for the rear A/C may be bad, and/or this 'high' side port may need to be purged <?>. I initially drew a vacuum at -30 Hg and it held overnight.

Can anyone offer a suggestion(s) here? I am perplexed as to why the front is blowing cool, but not the rear. Aren't the front and rear A/C all the same cooling circuit?