Had the OTR serviced about 3 months ago. Added 4 lbs 134A and some dye for leak detection later.
A week ago, the OTR didn't seems quite cold, but after about 10 minutes it seemed to work ok, though not really, really cold. Checked the refrigerant levels and the bottom sight glass seemed full and practically nothing in the top sight glass. The compressor oil looked a tad low, but it was showing in its sight glass, sloshing around.
Yesterday while under way the Hi/Low 24v voltage indicator on the dash was showing sporadically, never more than 3 seconds, and sometimes flickering. The analog voltage gauge shows pretty much topped out, just below 28v.
Turning on the 12v headlights seems to suck enough voltage to eliminate that hi/low warning light. Maybe the 24v regulator needs a slight adjustment. I think I can do that.
Today, though a nice day, I thought I'd run the OTR, and draw down some volts. Five minutes later, the OTR high pressure and OTR low pressure lights came on, the same indication as when I was low on refrigerant.
Turned off the OTR, a few minutes later the hi/low voltage light came on, turned on the headlights and no hi/low voltage warning.
Parked in high idle for 15 minutes, no headlights and no warning lights.
Haven't turned the OTR back on.
If you're still following this, are these events possibly related?