Remove, inspect, and reinstall receiver/drier or accumulator/drier; determine recommended oil quantity

Lesson Plan for

AUT 184-185/AUT 292

Automotive Service Technology Section C/Automotive Special Problems

Course HS Title: / Automobile Service Technology/Special Problems / Program:
KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No. / KCTCS Course Title
Introduction/Context / This lesson will instruct the student on how to remove, inspect, and reinstall receiver/drier or accumulator/drier, and determine recommended oil quantity. 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.
Prepared By / School / Date:
Grade Level / No. Students / No.IEP's: / Lesson Length:
Task
Remove, inspect, and reinstall receiver/drier or accumulator/drier; determine recommended oil quantity.
No. / Objective
1 / Given the proper tools and instruction, the student will be able to remove, inspect, and reinstall receiver/drier or accumulator/drier, determine recommended oil quantity, and pass a written test covering the task with 100% accuracy.

Connections:

Skills Standards:
OH 001
OH 002
OH 003
OD 002
OD 003
OD 005
Common Core Technical Standards:
TD-SYS-2
New Common Core Standards:
RST 11-12.2
RST 11-12 3

INSTRUCTIONAL MATERIALS/TECHNOLOGY

Teacher Designed Materials and Other Handouts


Textbooks and Workbooks

Author / Title/ISBN No. / Edition / Publisher / Pages
Chris Johanson / Auto Heating and Air Conditioning / 2009 / Goodheart Wilcox / 307-308
Motor Information Systems / ASE Test Preparation Guide / 2009 / Prentice Hall/Pearson / 463-464


Web Addresses

Title / Publisher / URL
Today's Class / Melior / www.todaysclass.com


Equipment

Quantity / Item / Source
As Needed / Recovery Recycling Machine (R12 and R134A) / Various
As Needed / Leak Detector (Refrigerant) / Various


Content/Presentation/Demonstration Outline

Explain to students that the ACCUMULATOR is a device on the low-side of an orifice tube system that performs two functions: It serves as a storage container to hold excess refrigerant, and also prevents liquid refrigerant from returning to the compressor. Let students know that the accumulator, which is located at the evaporator outlet, receives refrigerant in both liquid and vapor form. Tell students that refrigerant is stored at the bottom of the unit as a liquid and must be vaporized before it can be picked up at the top of the accumulator and returned to the compressor. The accumulator also contains a desiccant to remove moisture from the system.
Inform students that a drain hole at the bottom of the accumulator standpipe allows oil and some refrigerant to return to the compressor. Because of the large desiccant bag and the considerable amount of oil retained by the accumulator, tell students that it is important to accurately measure and replace the lost oil when installing a new accumulator. Let students know it is important to follow the service manual guidelines.
Instruct students that defective accumulators are replaced. The parts in an accumulator cannot be reached without cutting into the accumulator. Tell students that the clutch cycling switch can be removed from the accumulator.
Explain that accumulators should be replaced when they are leaking, the desiccant becomes water saturated, or there is evidence the oil return hole is plugged. Let them know that often the accumulator is replaced as a preventive measure when the system is opened or other components are replaced. Tell students it is always safer to replace the accumulator when you have any doubts about its condition.
Instruct students that to remove the accumulator, they should first recover the system refrigerant and remove all residual pressure. Then use two wrenches to remove the inlet and outlet fittings. Tell them to remove the single screw holding the bracket around the accumulator and remove the accumulator, and then transfer the clutch cycling switch and any other switch present from the old to the new accumulator as necessary.
Tell them to be sure and add the recommended amount of refrigerant oil to the new accumulator, then position the new accumulator on the bracket. They should then loosely install the inlet and outlet fittings using new O-rings, reinstall and tighten the bracket fastener, tighten the inlet and outlet lines, then evacuate and recharge the refrigeration system. When done, they should then start the HVAC system and check the accumulator and fittings for leaks.
Explain to students that the RECEIVER-DRIER is a high-pressure storage device located between the condenser outlet and expansion valve inlet. A desiccant bag in the receiver-drier removes moisture from the system. Tell students that the receiver-drier is replaced when there is system or component contamination, refrigerant leaks, collision damage, excessive ambient air entering an open system, and compressor replacement
Inform students that the signs of receiver-drier problems include loss of refrigerant moisture or debris contamination, desiccant particles in the system, refrigerant starvation due to blocked receiver-drier, a significant temperature difference between the receiver drier inlet and outlet, and frost on the bottom of the receiver-drier. Let them know that the receiver-drier is not serviceable and must be replaced when defective.
To remove and replace the Receiver/Drier, tell students to do the following: * Have them discharge the system using a recovery and recycling station, recycle the refrigerant, and measure how much refrigeration oil was extracted. * Next, tell them to disconnect the receiver-drier inlet and outlet line fittings and cap or seal them. Also, be sure to tell them to disconnect any electrical wiring to the receiver-drier assembly. * Instruct them to remove the attaching hardware and lift the receiver-drier from the chassis. Let them know that on some systems, the condenser must be removed before the receiver-drier. * Tell students to drain and measure any residual oil from the old receiver drier and transfer any switches or sensors from the old unit to the new one, * Install the replacement unit. Instruct them to tighten the hose connection fittings to specifications before tightening the mounting bracket bolts. * Inform them to reconnect any electrical connections on the receiver drier assembly. * Let them know to add enough fresh refrigeration oil to replace the amount lost during removal, along with the recommended amount of oil to compensate for what did not drain from the receiver-drier. * Finally, evacuate and recharge the system, then check the system for leaks.


Applications/Practice

1 / Refer to content


Evaluation and feedback Prior to Testing or Lab Work

1 / 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.)

1 / 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.)