Transcript AutoCAD Architecture 2008: Part I: Getting Started

Always Learning
CHAPTER 14
HVAC System Electrical and Electronic Controls:
Theory, Inspection, Diagnosis, and Repair
OBJECTIVES
After studying Chapter 14, the reader will be able to:
1.
2.
3.
4.
5.
Understand the relationship between volts,
amperes, and ohms.
Understand the circuits required for electrical
units to operate.
Be aware of the types of HVAC circuit problems
that may be encountered.
Be familiar with the procedure used to locate and
repair HVAC problems.
Complete the ASE tasks related to electrical or
electronics diagnosis and repair.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
3
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
KEY TERMS
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Alternating current (AC)
Ampere (amp)
Ampere-turns
Belt-lock strategy
Body control module (BCM)
Controller area network (CAN)
Circuit breaker
Complete circuit
Conductor
Diagnostic trouble code (DTC)
Diode
Direct current (DC)
Dynamic resistance
Electronic control module (ECM)
Electrostatic discharge (ESD)
Fuse
Fusible link
Ground
Ground circuit
High-resistance circuit
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
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Malfunction indicator light (MIL)
Multiplex
Ohm (Ω)
Open circuit
Parallel circuit
Positive temperature coefficient (PTC)
Pulse width modulation (PWM)
Relay
Scan tool
Schematic
Series circuit
Smart control heads
Smart motors
Static resistance
Volt (V)
Watt
Wiring diagram
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
INTRODUCTION
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At one time, the electrical control circuit for the
heat and A/C system was rather simple; a few
checks with a test light located most problems.
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•
Today’s systems have evolved into complex
electronic circuits with connections to the electronic
control module (ECM) and/or body control
module (BCM) .
The HVAC control head on some vehicles features
touchpanel operation and a digital readout of in-car
and outside temperature and can call up
diagnostic trouble codes (DTCs) .
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
5
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
SAFETY TIP
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The high-voltage circuits in hybrid vehicles
must be treated with respect and caution, and
this includes every bright orange wire and the
HV battery pack. Section 1.8 should be
reviewed before testing or working on the HV
electrical components.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
6
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
BASIC ELECTRICITY
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Three measurable aspects of electricity concern a
technician:
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•
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Volts (V)
Amperes (amps)
Ohms (Ω)
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
7
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
BASIC ELECTRICITY
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SYSTEM COMPONENTS
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Most electrical systems have five major
components:
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Power source
Protection devices
Control devices
Connecting wires
Output devices
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
8
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
BASIC ELECTRONICS
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SENSORS
CONTROL MODULE
ACTUATORS
MULTIPLEX AND CAN SYSTEMS
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
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Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
HVAC CIRCUITS
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POWER SUPPLY
COMPRESSOR CLUTCH CIRCUIT
BLOWER MOTOR CIRCUIT
ELECTRONIC CONTROLLED VARIABLE
COMPRESSOR
COOLING FAN CIRCUIT
HYBRID VEHICLE CIRCUITS
CLIMATE-CONTROLLED SEATS
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
10
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
ELECTRICAL CIRCUIT PROBLEMS
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OPEN CIRCUITS
HIGH-RESISTANCE CIRCUITS
SHORTED CIRCUITS
GROUNDED CIRCUITS
EMI, RFI
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
11
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
MEASURING ELECTRICAL VALUES
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MEASURING VOLTAGE
SOURCE VOLTAGE
MEASURING RESISTANCE
MEASURING AMPERAGE
INTERPRETING MEASUREMENTS
ADVANCED TESTING METHODS, ELECTRONIC SELFDIAGNOSIS
OBD-II
SCAN TOOLS
VARIABLE COMPRESSOR DIAGNOSIS
ECM FLASHING
ACTUATOR MOTOR CALIBRATION
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
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Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
TECH TIP
•
A test light can be used to check continuity of
a DC motor by connecting the light between
the motor leads and B. Connect the other
motor lead to ground, and the light should light
up. Next, rotate the motor at least one
revolution, and the light should stay on. If the
light goes out, there is a bad winding in the
motor, and the motor should be replaced.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
13
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
TECH TIP
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Ohm’s law includes a formula that compares
the relationship of the three major electrical
values. If you know two of the values, you can
easily calculate the third. This becomes handy
if one value, resistance, is hard to measure
but two other values, volts and current, can be
measured easily.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
14
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
TECH TIP
•
Most DMMs are self-ranging and give a
reading of any resistance value within their
ability. They also indicate in range Ω, kΩ, and
MΩ.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
15
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
TECH TIP
1.
2.
A small inductive pickup is commonly called an amp
probe or current probe ; the sensing portion is small
enough to clamp over a single wire from a harness.
This allows a fairly quick and easy method of
checking a circuit’s current flow.
Measuring the resistance of a clutch coil can be
difficult, but measuring voltage and clutch current
flow can be easy. If the voltage measures at 13.9 V
and there is a 3-amp current draw, solenoid
resistance is 13.9 / 3 = 4.6 Ω.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
16
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
ELECTRICAL SYSTEM REPAIR
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ELECTRICAL COMPONENT REPLACEMENT
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
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Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
TECH TIP
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If using a shrink tube , slide a piece of tube,
about ½ inch longer than the splice, over the
wire before connecting it in step 2. Slide the
tube away from the connection while
soldering it. After soldering the connection,
slide the tube to the proper location and heat
it to shrink the tube to lock it in place. If using
tape , make sure the tape is wrapped tightly
and smooth and looks neat.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
18
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
SUMMARY
1.
2.
3.
4.
5.
HVAC technicians should be able to measure voltage,
current flow, and circuit resistance.
HVAC technicians should be able to check for open,
shorted, grounded, and high-resistance circuits.
Components that have the correct current flow usually
have the correct voltage and resistance.
Electrical system repair includes wire replacement, wire
splicing, connector/terminal replacement, and component
repair or replacement.
Electronic systems usually include self-diagnosis and the
use of scan tools to read diagnostic trouble codes (DTCs).
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
19
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
REVIEW QUESTIONS
1.
2.
3.
4.
Electrical force is called ____________ ; a(n)
____________ is the amount of electrical current flow; and
____________ are the units of electrical resistance.
Most electrical circuits include a(n) ____________
____________ , ____________ ____________ ,
______________ ____________ , ____________ , and
____________ ____________ .
Electric wires transmit electricity through the
____________ while the current flow is contained by the
____________ .
The strength of a compressor clutch coil is determined by
the number of ____________ ____________ and the
amount of ____________ ____________ .
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
20
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
REVIEW QUESTIONS
5.
6.
7.
8.
9.
The diode at the clutch coil protects the electronic
____________ ____________ from voltage
____________.
An in-vehicle sensor is a type of ____________ that
increases resistance when the temperature
____________ .
A(n) ____________ converts a(n) ____________ signal
into an electrical signal.
If the ECM finds a problem in an electronic control system,
it will turn on the ____________ ____________
____________ and set a(n) ____________
____________ ____________ .
Most actuator motors contain a(n) ____________
____________ so the ECM will know the motor position.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
21
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
REVIEW QUESTIONS
10.
11.
12.
13.
A smart control head contains ____________ for motor
____________ .
____________ allows a pair of wires to be used for more
than one ____________ .
A strategy that prevents potential compressor problems
from damaging the accessory drive belt is called
____________ ____________ strategy, and it works when
the compressor ____________ ____________ signal
shows a slower speed than the engine.
A(n) ____________ ____________ is when electric
current leaves the wire it is supposed to be in to go to
another wire, and a(n) ____________ ____________ is
when electric current leaves the wire it is supposed to be
in and goes to ground.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
22
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
REVIEW QUESTIONS
14.
15.
16.
17.
18.
A blown fuse is often an indication of ____________
____________ flow.
An ECM can be damaged by ____________ if you touch
one of the terminals with your finger.
A clutch coil should have at least __________
__________ at the B terminal when the engine is running.
A ____________ ____________ allows you to read DTCs,
the signals from the sensors to the ECM, and the signals
from the ECM to the actuators.
The best way to clear a DTC without erasing the memory
of other electronic circuits is to use a(n) ____________
____________ .
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
23
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
1. Which of the following is the unit for electrical
pressure?
a.
b.
c.
d.
Amp
Ohm
Volt
Watt
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
24
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
2. Most automotive electrical systems use AC
current.
a.
b.
True
False
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
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Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
3. A fusible link is usually four wire sizes
____________ than the wire used in that
particular circuit.
a.
b.
c.
d.
Larger
smaller
Either a or b
Neither a nor b
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
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Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
4. Which of the following is considered an output
device in an ATC system?
a.
b.
c.
d.
Compressor clutch
Blower motor
Both a and b
Neither a nor b
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
27
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
5. Which of the following is monitored by a sensor in
an ATC system?
a.
b.
c.
d.
Ambient temperature
In-vehicle temperature
Sunload
All of these
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
28
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
6. Electrical mode doors in an ATC system usually
have a feedback sensor string connected to
them.
a.
b.
True
False
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
29
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
7. Which of the following test instruments can be
used on any automotive electrical circuit?
a.
b.
c.
d.
Test light
Ohmmeter
Analog multimeter
DMM
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
30
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
8. Modern electronic circuits can be damaged by
____________ .
a.
b.
c.
d.
electrostatic discharge
excess heat
rough handling
Any of these
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
31
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
9. Which of the following is true concerning
ohmmeters?
a.
b.
c.
d.
Ohmmeters are self-powered.
Ohmmeters can be used on live circuits.
Ohmmeters cannot be used to check continuity.
None of these are true.
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
32
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
10. A rule of thumb for clutch coil resistance is
____________ .
a.
b.
c.
d.
10 ohms
3 to 5 ohms
about 5 amps
5 to 10 ohms
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
33
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
11. A vehicle with an ATC system has heater and
defroster operation, but the A/C is not working
properly. To diagnose this problem, the technician
should ____________.
•
a. check for trouble codes
•
b. clear the trouble codes
•
Which is correct?
a.
b.
c.
d.
A only
B only
Both A and B
Neither A nor B
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
34
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
12. An example of a short circuit is a ____________ .
a.
b.
c.
d.
clutch coil with a resistance of 0.5 Ω
burned-out lightbulb
burned wire with bad insulation that touches
ground
Any of these
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
35
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
13. The blower motor runs on high speed only. This
indicates a faulty ____________ .
a.
b.
c.
d.
high-blower relay
resistor bank
Switch
None of these
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
36
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.
CHAPTER QUIZ
14. The vehicle overheats because the cooling fan
does not operate. This could be caused by a
____________.
a.
b.
c.
d.
faulty fan relay
bad blower motor ground connection
faulty blower motor
Any of these
Automotive Heating and Air Conditioning, 6/e
By Thomas S. Birch
37
Copyright © 2012, 2010, 2006, 2001, 1997, 1991 Pearson Education
Upper Saddle River, NJ 07458 • All rights reserved.