Thanks Larry, I will check that portion as well. I don't think mine uses a monovalve but it does have a complicated, interconnected maze of vacumn controlled valves and doors.
I do think the pressures are high on the high side of the system but look pretty respectable on the low side. Wouldn't that indicate an overcharge condition? On the other hand, wouldn't the foamy look in the sight glass indicate undercharge?
That is confusing me the most. My limited experience seems to tell me it is over charged and under charged too!
Thanks, for your reply.

__________________
Darrell

1984 300SD "Ole Girl"
207K

We had a 126. It had a monovalve. Also, the climate-control unit is notorious for problems, so either could be the trouble. If you're getting lots of heat, but have full power to the monovalve, that points to the valve itself. If there's no voltage at the valve, it points to the control unit or wiring.

Yes, the high side pressure MIGHT indicate an overcharge, but since it is a converted system, it's not alarming and it should perform reasonably well. If it were setting in my shop right now, I would recover the charge and then charge by weight starting with 70% of the R12 specified weight in R134a. I would then work up in 1 ounce increments while monitoring pressures & vent temp with engine running between 1,500 and 2,000 and my super squirrel cage fan in front of it simulating ram air.

With Matt indicating that it is a monovalve car, I would let the car cool off real good and pull the top off the monovalve. If it's flooded get a kit. If it's not it will be climate control system research time.

Good luck,