Cold DRIVEABILITY Test 3 - Air Cleaner Heated Air Intake System

Disconnect air duct from the air cleaner snorkel. Disconnect vacuum supply hose to the heated air intake system air temperature sensor. Connect vacuum pump to the air temperature sensor and apply 15 in. Hg vacuum to the sensor. Vacuum should build up to 15 in. Hg and close the heated air door when the air temperature is below 70°F (21°C). Vacuum should bleed down slowly, opening the heated air door.
NOTE: Models equipped with 2-Bbl. carburetors use a vacuum delay valve at the heated air door vacuum diaphragm. This delays the opening of the door when the vacuum bleeds off.
If vacuum builds up, but heated air door does not close, repair or replace door as necessary. If vacuum does not build up or bleed down, replace the air temperature sensor. If vacuum builds up and bleeds down, but heated air door does not open, repair or replace door as necessary.
If vacuum builds up, closes the heated air door and then bleeds down, proceed to COLD DRIVEABILITY TEST 4 on 2-Bbl. models. On 4 Bbl. models, remove vacuum hose from vapor containment door diaphragm. Connect a vacuum pump to the diaphragm and apply 15 in. Hg vacuum. Vacuum should hold and door should be open.
If vacuum does not hold or door is not open, repair or replace as necessary. If vacuum holds and door is open, reconnect hose to vapor containment door diaphragm. Remove vacuum supply hose from vapor containment door vacuum delay valve. Connect vacuum pump to delay valve and apply 15 in. Hg vacuum. Release vacuum.
Vapor containment door should open when vacuum is applied and close within 40 seconds after vacuum is released. If door does not close or open, replace vacuum delay valve. If door closes and opens okay, proceed to COLD DRIVEABILITY TEST 4 .