'91 300E constantly blowing warm air, not sure why...

[pifcat2]

First symptom was blowing warm air at any setting, second was continually blowing #7 fuses. I replaced the CCU with one from an '87 and the blower seems to work properly and the fuse doesn't blow anymore. I checked the 134a port with a autoparts can equipped with a gauge and doesn't indicate low but it says to "take it to a specialist." Before I do that I'd like to eliminate some possible faults.

Voltages:
key to Acc: 0V
key to far right: 12V
Engine running, no fan: 3V
Engine running, fan on: 13.65V
Engine running and wheel turned to max hot, fan low & high: 13.4V
Engine running and wheel turned to max cold: 4V +/- .20V
Engine running button to defrost: 4.2V

I can feel constant warm hoses to and from the heater core. I applied 12V to the heater valve and aux pump and both appear to operate (click at valve and motor running at pump). Both get power when the ignition was switched.

An earlier symptom was clicking under the dash. I believe vac pod(s) are blown but haven't checked them with a vac pump yet.