Thanks to the FAQs, I found a problem with my daughter's 1993 940 non-turbo A/C but have a few questions.

Everything looks like it should with the A/C but the air out of the vents was only about 58 F on the highway with recirc on, etc. The heater control valve looks like it is operating correctly with the vacuum but I think the valve is not stopping the flow of anti-freeze because the heater hoses are hot with the valve closed. I checked one of the other 940s and it's hoses were cool after an A/C drive. I ordered a couple Motorcraft heater control valve replacements (we still are driving a few 940s and a 740). It surprised me that the valve will close/open with the MCC (or is it an ECC?)heater control even with the engine off. I read there is a vacuum reservoir somewhere which must be where the vacuum is kept.
Where is the vacuum reservoir?
A simple question. How is the heater temperature regulated by the MCC? I don't think it is by the heater control valve since it is ether closed or open depending on whether the MCC control is off (vacuum to heater control valve and no flow through heater core) or on just past the off click (no vacuum to heater control valve and full flow to heater core?
Is the heater temp. to the vents controlled by cycling the heater control valve?

Thanks
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Mine: 3-940s running, 2-740 and 1-940 parts cars, and 3 1959 John Deere 630s (1 for parts), dtr1:3-940s, dtr2:1-740, 1