October 30: LEMON manuals on a temporary server, it is slow and having issues, download the manuals you need! Later in November we will switch back to the fast server.
Above 3280 Feet
Remove and plug 3 hoses from HAC valve and note idle quality. Poor idle quality should result due to insufficient air for high altitude operation. If idle quality remains unchanged, replace HAC valve.
Courtesy of FORD MOTOR CO.