a/c idle boost issue

Hi, I'm new here, so I'm not sure I'm asking this question correctly or in the proper place.

Problem: my 88 Accord (carb)won't adjust the idle speed when the a/c system cycles on/off. Whether the a/c system is running or not, the idle speed remains "slow" or unboosted as if the a/c system were not on & running.

What I know so far:
(1) The a/c idle boost vacuum diaphragm works correctly and there are no leaks in the associated vacuum hoses.

(2) The Idle Boost Vacuum solenoid seems to be working correctly--if I unplug the electrical plug to the solenoid from the harness and run a jumper wire from the battery to the solenoid it will dictate fast idle when it does NOT receive 12v, and will dictate slow idle when it DOES receive 12v.

(3) When I check the voltage coming to the solenoid in the wiring harness plug, I get about 14 volts when a/c system is cycled off, and about 10 volts when the a/c system is on & running and the a/c clutch is cycled on. As a result... the solenoid is always getting at least some current (10 or more volts), therefore it always dictates slow/unboosted idle (as when a/c clutch is cycled off).

It seems to me that something is allowing about 10 volts to come to the idle boost vacuum solenoid when the a/c clutch is cycled on it when in fact no voltage should be going to the solenoid at that time.

I don't know where to go from here. Any help will certainly be appreciated.

Thanks,
Paul