Automotive Service Technology Section D/Automotive Special Problems
Course HS Title:
Automobile Service Technology/Special Problems
KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No.
KCTCS Course Title
This lesson will instruct the student on how to identify and recover A/C system refrigerant. Knowledge of these techniques and the skills required to correct problems associated with this task are necessary for a student to acquire if they wish to compete for high paying, high skilled jobs in an Automotive Repair Facility. Entry level technicians need to be able to perform this task to 100% accuracy. Incorrectly performing this task can lead to an automobile accident or create customer satisfaction issues.
Instruct students that a recovery and recycling station connects to the vehicle through a manifold gauge set or a charging station. Tell students that once the vehicle system has been serviced, the refrigerant remaining in the manifold gauge set or charging station hoses must be recovered before the service ports are disconnected. Before recovery, instruct students to connect a manifold gauge set, and verify that there is pressure in the system. BE SURE AND LET THEM KNOW TO OBSERVE ALL SAFETY PRECAUTIONS AND EQUIPMENT OPERATING PROCEDURES.
Tell student that to recover refrigerant, they should follow these guidelines: Instruct students that with the manifold gauge set connected to the vehicle, attach the center hose to the intake side of the recovery and recycling station. Tell them to make sure the liquid valves of the recovery station are open, then open both manifold gauge valves. Next, have them switch the power on and start the recovery station compressor. Let them know that the compressor automatically switches off once recovery is complete. Tell students to monitor manifold gauges for several minutes. Explain that if pressure on either side rises above zero, they should switch the power on and start the recovery station compressor again. Tell students to then open the recovery station oil drain valve until all oil removed from the system drains from the separator. Let them know to be sure and note the amount of oil in the catch and add that much fresh oil to the system before recharging.
Inform students that in addition to purity standards for recycled refrigerant, SAE standards apply to refrigerant identification, handling, labeling, and storage.
Tell students to read all labels before using a container of refrigerant to make sure it is the correct type for the system being serviced. They can use a refrigerant identifier to determine what the vehicle system is charged with. Explain to students that this prevents equipment contamination. Let students know that new containers of R- 12 are painted white, while R- 1 34a containers are blue. Tell them to be sure and observe the same color coding when recycling. Be sure and emphasis to students that they should never put R-12 into an R-134a system, or vice versa, or contaminate equipment with another blend of refrigerant.
Explain to students that there are two types of recycling equipment: single-pass and multi-pass. Single-pass equipment sends the refrigerant through each recycling stage one time before storing it for use. A multi-pass system may not complete all the recycling stages before storing the refrigerant. Let them know that when refrigerant is needed to charge a system, the equipment cycles the refrigerant until it is clean and dry enough to meet standards for reuse. Tell students that either type of system can be used as long as it is UL approved.
Instruct students that recycling removes moisture and non-condensable gases from used refrigerant so that it conforms to purity standards established by SAE J1991. Tell students that for the best results and efficiency, the recovery and recycling station recovery tank should be full before recycling.
Inform students that recycling operations vary slightly by equipment, but the following is a general procedure they can follow: * Tell students to open both recovery tank valves on the recovery and recycling station, then switch the station power on and activate the switch that starts the recycle operation. * Instruct them to use the station moisture indicator as a sight glass. Explain that they can expect to see a stream of bubbles at start-up that quickly dissipates to no bubbles as the pump reaches peak efficiency. * Tell students to run the pump at peak efficiency for at least 30 minutes, then check the moisture indicator. Let them know that severely contaminated refrigerant can take several hours to recycle. Tell them to monitor the moisture indicator and switch the pump off once the refrigerant meets SAE standards. * After completing all the prior steps, tell them to switch the station power off and close both recovery tank valves. They should then disconnect, label, and store the recycled refrigerant tank according to regulations
Refer to content
Evaluation and feedback Prior to Testing or Lab Work
Objective 1. / Formative assessment / Instructor will observe students as they practice the procedure to assure correct procedure and safety practices are being followed. A checklist will be utilized to chart student progress on the task. Questioning techniques will be utilized as necessary to demonstrate student comprehension / Adaptations and/or accommodations for special needs students will be added if required.
STUDENT ASSESSMENT: (Assess student progress with performance criteria.)
Objective 1 / Summative assessment / written test questions on stated objective / adaptation and / or accommodations for special needs students will be added if required
IMPACT--Reflection/Analysis of Teaching and Learning: (How did students’ progress in relation to the state objectives? Was the instruction successful? Analyze samples of student work particularly that which is unsatisfactory, for the purpose of planning further instruction.)
REFINEMENT--Lesson Extension and Follow-up: (To be filled in as the lesson is modified during initial planning and/or during the teaching learning process.)