Transcript
HVAC/Climate Control Growing Service/ Repair Trends Presented by: Dennis Husband
Agenda Trends in Automotive HVAC: o Evolving electronic controls o Growing susceptibility to debris o Refrigerant charging & the decreasing margin for error o Addressing damaged hoses & lines o Trending service/repair opportunities
Agenda (cont’d) Best Practice Topics for Consideration by the AMRA Committee: o On‐hand A/C equipment needs o Emerging technician training needs o Best Practices/Protocol Considerations
Agenda (cont’d) Powertrain Temperature & Emissions Control Updates (hybrid and electric HVAC/temperature control): o A/C as part of emissions systems o Pressurized canisters o Heat pumps
Evolving Electronic Controls in Today’s A/C Systems o More digitally controlled sensors and controls than ever o Technicians with solid training on pulse width modulation will be able to more quickly and accurately diagnose and repair modern A/C systems o A lot has changed since the early 2000’s & is still changing
Let’s See What’s New
Newer Electronic Variable Displacement Compressors o No longer mechanically controlled o Some don’t even have clutches! o Increased fuel mileage o Lower emissions o Superior interior comfort o MUST be diagnosed differently
Denso SEU Compressor
o Often require specialized tools or a scan tool o We’ll call them “EVDCs” in this presentation
Let’s take a look!
What’s Different about Newer EVDCs? o Have control valves that are electronically controlled o Some are clutch‐less, others aren’t…the old technique of looking to see if the clutch is engaged doesn’t apply anymore o A scan tool, DVOM, and other specialized tools may be required to properly diagnose these compressors for a failure or a performance issue o Adding complexity, multiple system sensors act as inputs to the controller
What’s Different about Newer EVDCs? o All of these sensors must function properly & be seen by the controller in order for compressor output to match the heat load on the system o Compressor gauge readings will be equal if the controller has no information to interpret the heat load o The control valve or other sensors can fail while the compressor is still good
Diagnosing Newer EVDCs Torque Limiting Drive Hub. No Clutch!
Diagnosing Newer EVDCs
Diagnosing Newer EVDCs
Diagnosis of Pulse Width Modulated Components Let’s discuss pulse width modulation
A Lab Scope is a good tool for diagnosing components that are pulse width modulated
Pulse Width Modulation 33% Duty Cycle 50% Duty Cycle 75% Duty Cycle
o How Different PWM Signals Appear On A Scope o Significant Changes in Pulse Width Should Result in a Change in System Pressures 246
Diagnosing Newer EVDCs o Operation of EVDC, starting with system in balance, (i.e. ‐ no cooling load) o Solenoid valve is closed o Duty cycle is 0%
Notice the duty cycle line (On / Off), which is a straight line at the off level
o Compressor shaft swash plate is shown straight vertical (implying there is no pumping action* from the pistons)
*Actually the compressor doesn’t go down to zero , but when there is no cooling load, it’s very close, held in a slight pumping tilt by the spring in the crank chamber.
Diagnosing Newer EVDCs At 50% Duty Cycle: o Solenoid valve opens to create a pressure differential between the crank chamber and the cylinder
The duty cycle line is now half on, half off
o Higher pressure in the cylinder “pushing back“ against the piston to tilt the swash plate
Diagnosing Newer EVDCs At 100% Duty Cycle: Solenoid valve fully open creating: o Maximum pressure differential o Maximum pushback against the piston
The duty cycle line is now 100% along the on level.
o Maximum tilt of the swash plate o Maximum piston displacement / stroke length.
Examples of 18 Different Inputs Volkswagen Uses To Reduce Compressor Output Or Turn It Off
Safety When Working on Clutchless EVDC Systems This label from a Jeep Compass states that the A/C system should not be operated under vacuum. Compressor damage will result… But what about during a ‘not charged’ condition?
Diagnosing Newer EVDCs Electronic Control Compressor Scan Tool o Trend of more tools designed for diagnosing ECVDCs o Some (such as this System Scanner) allow for o Normal system control or manual control from 0% up to 100% plus cooling fan control o One button check of control valve resistance o Supplied with multiple connectors to work with many different vehicles o Will prevent codes from being set
New Sensors in Some Applications That Can Impact A/C Function CO2 / CO Sensors • Can change the blend‐door / air recirculation settings based on both interior and exterior air quality GPS Sun‐Positioning Sensors (Acura) • Changes blend‐door and fan speed based on sun’s relative position to the car Lock sensors (Toyota, etc.) • Detects belt slippage and will disengage the compressor
Diagnosing Newer EVDCs o Customer complaints of poor cooling could be related to the programing of the refrigerant system controller o Tightening CAFÉ standards resulting in luxury accessories, such as A/C, are being tuned to improve fuel economy o Manufacturers limit the amount of information related to this type of complaint o Always check for TSBs when the system operation seems normal, yet the customer is not satisfied with the performance
Growing Susceptibility to Debris o Efficiency now out‐prioritizes durability in A/C design o Result: substantial design changes to compressors & condensers o Internal tolerances in specific designs are extremely unforgiving o Materials use has changed to aid in weight savings o What is the implication? o Trace amounts of debris can cause system failure and comebacks
Let’s look at some of these changes
Scroll Compressors Design Highlights: o Fewer moving parts (no pistons) o Lighter than piston‐style compressors Compact, Quiet, & Efficient Challenges: o Very susceptible to lubrication issues o Debris only a few microns in size can produce catastrophic results
Changes in Condenser Design 1) 8mm tube and fin (R‐12) 2) 6mm Tube and Fin (R‐134a) 3) 6mm parallel flow (circa ‘92) 4) Micro‐Tube Parallel Flow (2004+)
Let’s look closer…
1 3 2 4
Micro‐Tube Parallel Flow Condensers (Flushable?) o Condenser designs have changed over the last decade o Passages now so small that a straight‐pin won’t pass through them o Successfully flushing debris isn’t always possible
Parallel Flow Design Inlet
Zone1 Zone2
Zone3 Zone4
The Transition Areas Between Zone 1-2, Zone 23, and Zone 3-4 Cannot Be Efficiently Flushed.
Cut‐Away of Parallel Flow Condenser Post Compressor Failure Sample from an ‘04+ Honda CR‐V Post Compressor Failure #1 failing A/C system in the US. Why?
Micro‐tube sections terminate into unserviceable, multi‐ chamber manifold
Potential Solutions to Address Susceptibility to Debris o Thorough flushing of serviceable components not being replaced o Replacing components that cannot be cleared of debris o Replacement with fortified/improved design parts o Installation of inexpensive in‐line suction‐side debris filters
Refrigerant Charging: Decreasing Margin for Error o Automotive refrigerant systems typically designed with a capacity window of +/‐ 10% the specified amount o Total capacities of these systems have decreased dramatically o With decreased capacity, capacity window has decreased too o As we will demonstrate, proper lubrication can only occur when there is a correct charge of refrigerant
Temperature Testing
GAUGE READINGS CANNOT DETERMINE CHARGE… But proper temperature testing of components can indicate whether the system is charged properly
Temperature Testing o Temperature testing can ensure the accuracy of the charge and test the compressor for overheating via starvation of lubrication o Refrigerant loss exceeding 5% annually indicates excessive leakage o Contact probe‐style thermal couplers are recommended over infra‐red temperature guns for two reasons: 1) Accuracy of most infra‐red guns within the temperature window vs. required accuracy to identify A/C system issues 2) Risk of reflections & other nearby heat‐sources under the hood resulting in inaccurate measures
Pressure / Temperature Relationship Chart ºF
Blue Indicates – below freezing
32° F Freezing
ºC
HFC134a
CFC-12
ºF
ºC
HFC134a
CFC12
-60
-51.1
21.8
19.0
55
12.8
51.1
52.0
-55
-48.3
20.4
17.3
60
15.6
57.3
57.7
-50
-45.6
18.7
15.4
65
18.3
63.9
63.8
-45
-42.8
16.9
13.3
70
21.1
70.9
70.2
-40
-40.0
14.8
11.0
75
23.9
78.4
77.0
-35
-37.2
12.5
8.4
80
26.7
86.4
84.2
-30
-34.4
9.8
5.5
85
29.4
94.9
91.8
-25
-31.7
6.9
2.3
90
32.2
103.9
99.8
-20
-28.9
3.7
0.6
95
35.0
113.5
108.3
-15
-26.1
0.0
2.4
100
37.8
123.6
117.2
-10
-23.3
1.9
4.5
105
40.6
134.3
126.6
-5
-20.6
4.1
6.7
110
43.3
145.6
136.4
0
-17.8
6.5
9.2
115
46.1
157.6
146.8
5
-15.0
9.1
11.8
120
48.9
170.3
157.7
10
-12.2
12.0
14.6
125
51.7
183.6
169.1
15
-9.4
15.0
17.7
130
54.4
197.6
181.0
20
-6.7
18.4
21.0
135
57.2
212.4
193.5
25
-3.9
22.1
24.6
140
60.0
227.9
206.6
30
-1.1
26.1
28.5
145
62.8
244.3
220.3
35
1.7
30.4
32.6
150
65.6
261.4
234.6
40
4.4
35.0
37.0
155
68.3
279.5
249.5
45
7.2
40.0
41.7
160
71.1
298.4
265.1
50
10.0
45.3
46.7
165
73.9
318.3
281.4
RED figures - In Hg. Vacuum
freezing
Red Indicates Hg. Vacuum
BLUE figures - Below 265
Temperature Testing Temperature Readings Must Be Accurate ANY tool used in temperature ranges outside of their designed operating range can return results not accurate enough for proper diagnostics
Under‐Charge Test Objective: Measure & compare the following with a proper refrigerant charge vs. a 25% undercharge 1. 2. 3. 4. 5.
High‐side & low‐side pressures Temperature readings at the condenser, evaporator, and accumulator Vent temperature readings Compressor operating temperature Determine how an undercharge effects lubrication
Under‐Charge Test Vehicle: System: Factory Charge: Undercharge:
1998 Jeep Cherokee Fixed Displacement Fixed Orifice Tube 20 Ounces 15 Ounces (=25% Undercharge)
Under‐Charge Test Equipment Compressor Case Temperature
Condenser Inlet & Outlet Temperatures
Evaporator Inlet & Outlet Temperature
Accumulator Inlet & Outlet, Ambient & Vent Temperature
Under‐Charge Test With Proper Charge High Side: Low Side:
187 PSI 23 PSI
With 25% Undercharge High Side: Low Side:
185 PSI 20 PSI
Under‐Charge Test Temperature Readings: With Proper Charge Ambient Temperature: 89 F Vent Temperature: 47.4 F
With 25% Undercharge Ambient Temperature: 92.3 Vent Temperature: 48 Note: With a 25% undercharge, vent temperature only increased by .6 degrees Fahrenheit
Under‐Charge Test Condenser Readings With Proper Charge Condenser Differential: 38 F
With 25% Undercharge Condenser Differential: 61 F
Under‐Charge Test Evaporator Readings: With Proper Charge Evaporator Differential: 0.2 Degrees F
With 25% Undercharge Condenser Differential: 31.7 Degrees F
Under‐Charge Test Accumulator Readings: With Proper Charge Accumulator: 39.3 Degrees
With 25% Undercharge Accumulator: 69.2 Degrees
Under‐Charge Test Compressor Case Readings: With Proper Charge Compressor Temperature: 124.5 Degrees
With 25% Undercharge Compressor Temperature: 151.5 Degrees 27 Degree Increase (21.6%)
Under‐Charge Test Compressor Oil Drained From Compressor After Running With Full Charge For 1.5 Hours:
1.80 Ounces Oil Drained From Compressor After Running For 50 Minutes With 25% Undercharge:
0.50 Ounces
70% Less!!!!!!!!!
The Effects Of Air Contamination • With 0% Air Contamination High Side: 165 PSI Low Side:32 PSI Condenser Temperature Differential: 38 Degrees Evaporator Temperature Differential: 0 Degrees
• With 7.7% Air Contamination High Side: 200 PSI Low Side: 31 PSI Condenser Temperature Differential: 65 Degrees Evaporator Temperature Differential: 9 Degrees
2011 Ford Crown Vic
• With 18.9% Air Contamination High Side: 400 PSI Low Side: 45 PSI Condenser Temperature Differential: 102 Degrees Evaporator Temperature Differential: 14 Degrees
Refrigerant Identifier
Some Notes About Compressor Oil Let’s discuss the importance of using the proper type of and viscosity of oil for the compressor and vehicle Common aftermarket types of oil & weights: o Pag 46 o Pag 100 o Pag 150
Some less common “OE” weights of PAG oils: o Pag 56 – 68 – 80 – 125
There are also some aftermarket additives with 3rd‐party lab tests that indicate improvements to system performance & reduction of comebacks.
Damaged Hoses & Lines Options to address a damaged A/C line or hose assembly: o Repair in place o Remove, repair, & reinstall o Replacement There are pros & cons to all three
Repairing a Damaged Hoses or Lines Pros of Hose & Line Repair o Availability of a new part isn’t an issue o Potential for substantial decrease in labor time
Cons of Repair o Adds potential leakage points o Repair may occur in non‐ideal conditions o Quality/Success of repair dependent on multiple variables o Age of the rest of the repaired line/hose is unchanged
Repairing a Damaged Hoses or Lines Pros of Replacement o O.E.‐like replacements have no additional leakage points o Often factory pressure/quality tested o Manufacturers typically use the latest in joint‐sealing technology o Produced in clean manufacturing environment o May offer improved design over original equipment o Comeback may be covered by the supplier/manufacturer
Repairing a Damaged Hoses or Lines Cons of Replacement o Quality of part depends upon supplier o May require substantial additional time for delivery + R&R
Verdict Regardless of the decision to repair or replace, identifying the cause for failure and resolving it (i.e. – finding a rub‐point, missing hose tie, bent heat shield, etc.) is critical
Trending Service/Repair Opportunities o Cabin Air Quality Services (evaporator/heater core cleaning)
o Added‐Value Under Dash Part(s) Replacement o Efficiency/Age Reflashes for Hybrid/Electric Vehicles
Cabin Air Quality Services o Evaporator coil cleaning continues to grow in popularity o Primary customer complaint is often smell o Cabin filters only remove allergens & debris before the blower box o Core cleaning can remove allergens growing in the blower box • Mold • Mildew • Dust
When Accessing Under‐dash HVAC o Under‐dash HVAC work often calls for 4+ hours of labor o Under‐dash parts are typically relatively inexpensive
Part
Average Price
Evaporator
<$80
Heater Core
<$60
Blower Motor
<$90
Expansion Valve
<$30
o Suggesting replacement of more than one component is a trend o Similar to replacing the water pump / timing belt together
Hybrid Age/Efficiency Reflash Opportunities o Dealerships are now offering reflash services that address programming changes which can improve the efficiency & performance of high mileage/high age hybrid systems o Currently the only information that can be found is through dealership information networks o Potential “Right to Repair” discussion?
HVAC Best Practice Topics for Consideration by the Committee 1. On‐hand HVAC equipment needs 2. Emerging technician training needs 3. Best Practices/Protocol Consideration
On‐Hand HVAC Equipment Suggestions Thermal coupler or equivalently accurate equipment o When used properly, allows faster & more accurate analysis of system condition without having to crack the HVAC system o Minimizes user error & surrounding heat‐source impact on results
Compressor Scan Tool o Enables observation of pulse width commands in different heat load scenarios o Allows manual manipulation of pulse width commands
On‐Hand HVAC Equipment Suggestions Refrigerant Identifier o Detects air and other contaminants o Confirms or eliminates refrigerant contamination as part of the problem o Protects against contaminating your refrigerant supply
Leak Seal (Stop Leak) Filter Guard o Prevents contaminating your equipment (potentially voiding the warranty) o Prevents cross contamination to other vehicles
HVAC Best Practice Topics for Consideration by the Committee Best Practices/Protocol Consideration o How to identify and treat vehicles with constant‐run A/C systems when they are discharged or under vacuum o How to address post‐contamination replacement of parts, particularly condensers o When to suggest installation of in‐line debris filters o When to suggest under‐dash “value add” replacements o How to explain to customers the reasons for suggestions
HVAC’s New Role in Temperature & Emissions Control
A/C as Part of Hybrid/Electric Emissions Systems o Most rely on the A/C system to control temperatures in the battery systems of the vehicles o Example: ’07+ Camry Hybrids have a vent visible under the rear window through which in‐cabin air is vented to cool the battery o The concept: Batteries are “comfortable” and operate well in the same temperature ranges that people are comfortable o Others use the A/C system but with less visible indicators o An improperly functioning A/C system will now prompt a check engine light
Pressurized Canisters Heat Pump are electrical circulation pumps within cooling systems and can often be found in conjunction with Pressurized Thermal Canisters in hybrid‐electric vehicles As part of the pressurized canister system: o Impacts catalytic converter & emissions component operating temperatures o Must be addressed when diagnosing overheating issues, flushing cooling system, purging air o Manufacturer’s instructions need to be followed carefully & may call for the use of a factory scan tool to control engine, cooling fan, water pump, and thermostat cycling
Questions??
Thank You For Having Us
Diagnosing Newer EVDCs 1. Preliminary inspection of the compressor for leakage at a hose connection or shaft seal and verification refrigerant circuit has an adequate amount of refrigerant for operation 2. Inspection of the drive hub bridges to verify the compressor is not seized 3. Check and inspect the dash controls to verify vent function and control relay operation. (Look for the a/c led on the dash to illuminate if so equipped) Note that vehicles with auto temp control run the compressor in multiple mode settings including heater. 4. With the climate system on and the a/c commanded to function, check system pressures on the low and high side for changes. Evaporator temperature should be maintained at slightly above freezing. High side pressure will vary widely depending on the ambient temperature. (Continued)
Diagnosing Newer EVDCs 5.Gauge movement indicates compressor is functioning. No movement indicates a no pump condition. 6. No pump condition requires that voltage be measured at the control valve. A factory scan tool or an after market scan tool with the proper software can be used as well as a DVOM. 7. Scan tool should be used to check for DTC’s in the power train controller. 8. Control valve resistance should be measured at the control valve connector on the rear of the compressor when a DTC with a voltage related code is present. (Continued)
Diagnosing Newer EVDCs 9. When resistance at the control valve connector is verified to be acceptable a voltage test at the control valve should be performed with a scan tool or DVOM. 10. Resistance at the control valve should be 10.0 to 18.0 ohms. Voltage at the control valve can range from 4.5 volts to battery voltage depending on the vehicle, trim level, ambient temperature, desired interior temperature and engine operating temperature. 11. If the voltage signal is present and resistance is acceptable but the gauge readings stay in the equalized position, the heat load should be increased on the system. With a full heat load on the system there should be battery voltage or very close to battery voltage at the control valve connector. (continued)
Diagnosing Newer EVDCs 12. Battery voltage at the control valve connector indicates the system is commanded to operate at 100% duty cycle and the gauge readings should be 25 to 35 on the low side and 100 psi plus the ambient temperature on the high side. Humidity, air flow at the condenser and the ambient temperature will play a role in the high side operating pressure seen on the gauge set. 13. If the voltage reading is at battery voltage and the compressor output is not at 100% the compressor is faulty. If the voltage reading is below battery voltage with a maximum heat load the system sensors or electronic controls will require further diagnosis.
