AC cycles 1x then drops off at highway speed. Under 45 MPH works great. on 2001 Honda Civic

Civic EX /5-stick /177K mi. Q: At Hwy speeds the AC cycles 1x then drops off & blows hot & moist. Under 45 MPH works great (inc stationary). Honda mech's have replicated the problem but can't determine the cause. So far the thermal protector has been replaced, & overall system checked out, but problem persists. The car has been properly maintained, everything else works great, no codes. back w/Honda dealer, 1wk and counting...

by in Lebanon, OH on June 10, 2010
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1 answer 1 comment
ANSWER by , June 10, 2010
Check the Throttle Position Sensor. This may sound wacky but hear me out, the A/C is designed to cut off at about 1/2 to full throttle, so if the Throttle Position Sensor has a worn spot, at steady cruise speeds it can go 'open' which makes the engine think that the driver wants full throttle, then the A/C system is shut off, to give more power. I have seen this before on other types of cars.
COMMENT by , June 17, 2010
Thanks for the feedback. Shortly after your response Honda called stating they had again replicated the problem, and inspected the car while running w/problem engaged. Discovered the AC clutch was culprit and replaced. I've had the car back 5 days and it seems to be fixed. To their credit, Honda ate the cost of this second fix.