Air Conditioning (A/C) System (12.03)
Climate Control (12.00)
May 2007 Workshop Manual 12-3-17
Symptom (7)DescriptionPossible Cause
Air from vents not cold enough. Magnetic clutch operates but A/
C system malfunctions. • Drive belt fault
• Fault in blower unit or condenser
• Fault in Receiver / Drier or expansion valve
(valve closes too much)
• Fault in refrigerant lines
• A/C compressor system fault, insufficient compressor oil
• Over filling of compressor oil, fault in expansion valve or A/C unit air mix link system
Symptom (8)Possible Cause
No cool air. Magnetic clutch does not
operate. • Fault in PCM A/C cut control system
• Fault in A/C Module
• Fault in refrigerant pressure switch
• Fault in PCM (A/C signal)
• Fault in PCM (IG1 signal)
• Fault in A/C compressor
•Fault in A/C relay
• Fault in Evaporator Temperature Sensor
Shake the wiring harness and connectors wh ile performing the inspection to discover whether poor contact points are the
cause of any intermittent malfunctions. If there is a problem, check to make sure connectors, terminals and wiring harnesses
are connected correctly and undamaged.
Symptom (9)Possible Cause
Noise while operating A/C
system. Noise from magnetic clutch, A/C
compressor, hose or refrigerant
line. • Magnetic clutch operation noise
• A/C compressor slippage noise
• Hose or refrigerant line interference noise
AML EOBD System Operation Summary
Rory O’Curry Aston Martin Lagonda CONFIDENTIAL 1 May 2009
[email protected] AML EOBD Monitors 07 ROC.doc Page 10 of 43
HO2S Monitor
Front HO2S Signal
The time between HO2S switches is monitored after vehicle startup and during closed loop fuel
conditions. Excessive time between switches or no switc hes since startup indicate a malfunction. Since
'lack of switching' malfunctions can be caused by HO2S sensor malfunctions or by shifts in the fuel
system, DTCs are stored that provide additional information for the 'lack of switching' malfunction.
Different DTCs indicate whether the sensor was st uck lean/disconnected (P1131, P1151), stuck rich
(P1132, P1152) or stopped switching due to excessive long term fuel trim corrections (P1130, P1150).
HO2S 'Lack of Switching' Operation:
DTCs Bank 1 – P0132, P2195, P2196
Bank 2 – P0152, P2197, P2198
Monitor execution continuous, from startup and while in closed loop fuel
Monitor Sequence none
Sensors OK TP, MAF, MAP, ECT, CHT, ACT, IAT
Monitoring Duration 30 to 60 seconds to register a malfunction
Typical HO2S 'Lack of Switching' entry conditions : Minimum Maximum
Throttle Position part throttle
Idle State (not at idle, part throttle)
Engine Load 20% 60%
Time since engine start-up 180 seconds
Inferred Exhaust Temperature 800 oF
Typical HO2S 'Lack of Switching' malfunction thresholds:
< 5 switches since startup after 30 seconds in test conditions
> 60 seconds since last switch while closed loop
> 30 seconds since last switch while closed loop at Short Term Fuel Trim limit
HO2S lack of switching temporary disablement conditions (other than entry requirements) :
Air Charge Temperature, ACT (or IAT) < -20 °F (minimum Cold Climate Test Temperature).
Failure of the sensors mentioned in the above “Sensors OK” section.
The HO2S is also tested functionally. The response rate is evaluated by enteri ng a fixed frequency square
wave, fuel control routine. This routine drives the air/fuel ratio around stoichiometry at a calibratable
frequency and magnitude, producing pr edictable oxygen sensor signal amplitude. A slow sensor will show
a reduced amplitude. Oxygen sensor signal amplitude below a minimum threshold indicates a slow sensor
malfunction (P0133 Bank 1, P0153 Bank 2).
HO2S Response Rate Operation:
DTCs Bank 1 - P0133, Bank 2 - P0153
Monitor execution once per driving cycle
Monitor Sequence none
Sensors OK ECT, IAT, MAF, MAP, VSS, CKP, TP, CMP, no misfire DTCs
Monitoring Duration 4 seconds
