Diagnostic Test |
Symptom |
Possible Cause and Repair Procedure |
A |
Cool discharge air when system is set to 30*C |
Heater Malfunction - Check if hot water valve is open, if not check vacuum hosesBlend door not in maximum heat position - Check blend door motorCabin sensor is shorted - Check sensor and sensor wiring loom |
B |
Warm discharge air when system is set to 18*C |
Air conditioning clutch malfunction - Check air conditioning clutch, and wiring loomBlend door not in maximum cold position - Check blend door motorLow refrigerant level - Refill air-conditioning refrigerant |
C |
No Fan |
Faulty wiring - Check wiringFaulty Fan Controller - ReplaceFaulty fan motor - replaceFaulty control unit - replace |
D |
High Fan only |
Faulty wiring - Check wiringFaulty fan controller - replacefaulty control unit - replace |
E |
Fan will not go to high speed |
Faulty wiring - Check wiringFaulty fan controller - replacefaulty control unit - replace |
F |
A/C is on continually |
Short circuit in evaporator sensor - Check resistance across sensor terminals. Change if sensor shortedFaulty wiring - Check wiringFaulty control unit - replace |
G |
Control head digits and LED's do not light up |
Fuse - Check and replace fuseIgnition circuit - Check wiringIllumination circuit - Check backlight globe and replaceIllumination dimming circuit - Check Body electronics moduleGround circuit - Check wiringFaulty control unit - replace |
H |
System stays in cold engine lockout air to screen low fan speed when engine has reached normal operating temperature |
Engine sensor open circuit - Check sensor is connected - Check circuit - Check sensor resistance should be less than 5KOhm |
I |
System does not control temperature |
Cabin sensor hose not connected to sensor or air hose - Inspect and repair cabin sensor vacuum hoseCabin engine vacuum line sensor obstructed or not installed properly - Inspect and repairCabin sensor hose kinked or damaged - Inspect and repairVacuum line disconnected - Check and connect |
J |
System runs hot during high sun load conditions |
Sun load sensor open circuit - check if sensor is connected - Check sensor is not covered - Check sensor function - Check wiring |
K |
System overcools at normal comfort setting |
Ambient temperature short circuit - Check circuit - Check circuit - Check resistance across sensor terminals, change sensor if shorted |