Thread: Aircon drops voltage

Hi, IMO a short which drops the voltage to 0 should blow the fuse so better make sure first that the blower is the problem not some weak contact which can't bear the load.... for that try to improvise and connect wires to it's plug and feed it directly from the battery through a 30A fuse...if it runs this way most probably one of the relays is weak or some bad contact in a plug on the blower's circuit, usually the power or blower relay used to get loosen...if it doesnt run or blows the fuse then you can search for another...see attachment

Wouldn't it most likely be the speed dropping resistor ie something in the control unit. There is a test for aircon operation you can do so google it.

Take the fan out and run it up on 12v . You will soon see if it is faulty.

Judging by the number and low cost on ebay they seem very reliable.
Regards Philip A

Climate control self diagnostic check

The climate control does a self check on start up, if it has no faults all remains quiet. If it has faults then you get chimes and the climate control panel flashes before returning to normal and the climate control ECU adjusts to accommodate the faults where possible.
To check what the faults are you need to do a diagnostic check manually which results in fault codes being shown on the Climate control panel. To put it into diagnostic mode press and hold the AUTO switch and the air distribution switch, then turn the ignition switch from off to on. The audible warning sounds and the control panel display illuminates. FC is shown in the LH temperature window and the results of the check are shown as a two digit fault code in the RH temperature window. If a fault is detected, the audible warning sounds three times and the AUTO window on the display flashes on and off for about 20 seconds. If more than one fault is detected, the fault codes cycle in numerical order at 1Hz. The audible warning sounds as each fault code is shown. In low light conditions to avoid false sunlight sensor fault indications, the sunlight sensor should be illuminated with a strong light source.
Fault Codes
00- no faults found
11-incar temp sensor
12- outside temp sensor
13-AC evaporator temp sensor
14-heater radiator temp sensor
21- AC sunlight sensor left
22 right
31 AC/heater air mix flap motor left
32 right
33 AC/heater air direction motor

Originally Posted by PhilipA

Wouldn't it most likely be the speed dropping resistor ie something in the control unit. There is a test for aircon operation you can do so google it.

The aircon version is not with resistor pack it has a power transistor for blower speeed controll and if this fails the blower will run only on high speed cos on high speed it gets direct feed through the relay everything else is bypassed so as long as it doesnt work on full speed the problem is not there also the blower is not covered by diagnostics

Originally Posted by chilla

Hey guys, I know there are a few similar threads on this, but I couldn't see an exact answer.
My aircon blower isn't blowing on any speed setting. Under the glovebox, there is 12V on the 2 pin plug (with it disconnected) after the relay. As soon as I plug in the blower, the voltage drops to 0. So I am guessing either the blower is wrecked, or there is a short in the circuit somewhere dropping the voltage when a load is connected. Can anyone suggest what the most likely scenario is? I'm in Brisbane, where's my best bet to go source a blower, 2nd hand or new and what sort of prices am i looking at? Also, in the pic below which screws am I looking at removing to get it out? The red circles (if so where is the 3rd, I can only find two.) Or the yellow one(s) which would drop the bottom of the housing of. Seems like a lot of plugs and cables to remove if I need to swap it out?
Thanks guys.

you could be chasing a high resistance fault.

with no load the voltage is there.

with a load the voltage goes away in the form of heat at the point of resistance.

Originally Posted by sierrafery

Hi, IMO a short which drops the voltage to 0 should blow the fuse so better make sure first that the blower is the problem not some weak contact which can't bear the load.... for that try to improvise and connect wires to it's plug and feed it directly from the battery through a 30A fuse...if it runs this way most probably one of the relays is weak or some bad contact in a plug on the blower's circuit, usually the power or blower relay used to get loosen...if it doesnt run or blows the fuse then you can search for another...see attachment

Thanks a lot. My mrs just called me and said the aircon started to work again. I forgot to mention it is intermittent, but has been real bad lately. I'm leaning towards bad connection in the circuit rather than blower itself. Is the blower relay the one before the plug in the circuit? If so, which is the power relay you refer to?

The relays are close to each other, C153 = blower relay, C901 = power relay, both involved and the cavities in theyrs plugs used to get loose

Originally Posted by sierrafery

The relays are close to each other, C153 = blower relay, C901 = power relay, both involved and the cavities in theyrs plugs used to get loose

Ok, so a common problem is the relay base, not the relay itself