19
Special Information for
Automotive Technicians (Continued)
so that no areas of potential leaks are missed. If a leak is found,
always continue to test the remainder of the system.
7. At each area checked, the probe shall be moved around the
location, at a rate no more than 25 to 50 mm/second (1 to 2
inches/second) and no more than 5 mm (1/4 inch) from the
surface completely around the position. Slower and closer
movement of the probe greatly improves the likelihood of finding
a leak.
8. An apparent leak shall be verified at least once by blowing shop
air into the area of the suspected leak, if necessary, and
repeating the check of the area. In cases of very large leaks,
blowing out the area with shop air often helps locate the exact
position of the leak.
9. Leak testing of the evaporator core while in the air-conditioning
module shall be accomplished by turning the air-conditioning
blower on high for a period of 15 seconds minimum, shutting it
off, then waiting for the refrigerant to accumulate in the case for
time specified by section 9.1 (below), then inserting the leak
detector probe into the blower resistor-block or condensate
drain-hole if no water is present, or into the closest opening in
the HVAC case to the evaporator, such as the heater duct or a
vent duct. If the detector alarms, a leak apparently has been
found.
9.1 The accumulation time for evaporator testing is 13 minutes.
9.2 Following any service to the refrigerant system of the vehicle,
and any other service which disturbs the refrigerant system, a
leak test of the repair and of the service ports of the refrigerant
system shall be done.
