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[General] How To Diagnose HVAC Fan Problems VT - VZ

Nut Kracker

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Nah.....looking at the wiring diagram again, it probably wont be the fuse. Because if it was,
you wouldn't have the rear demister or any instruments.
Basically, the only things it could be are....
The fuse
The blower relay. NOT THE BLOWER INHIBIT RELAY.
The switch.
Or bad wiring.

There are two relays for the fan.
The Blower Inhibit relay and the Blower relay.
If the Blower Inhibit relay was faulty. there would be NO fan at all. As this one controls ALL fan speeds.
The Blower relay on the other hand, ONLY controls the fan's highest speed setting.
And the resistor pack ONLY controls the first three settings.
Which relay did you change??
The Blower relay on my daughter's old VX had an intermittent fault, until it finally went the way of the Dodo.
 

Mitchell....

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I got a vy calais my A/C is just blowing room temp air the fan still comes kicks in once A/C is turned on any ideas what this could be
THIS "HOW TO" IS ONLY FOR THE MANUAL HVAC SYSTEM AND NOT FOR THE AUTOMATIC CLIMATE CONTROL.

I've been looking around this Forum and I have found that alot of responses as to why the HVAC
(Heating, Ventilation and Air Conditioning) fan is not working, is that the resistors have packed it in.
This is not entirely true.
The fan switch is divided into two parts. Firstly, the lower speeds, 1,2 and 3 run through the resistors to the fan. The 4th speed (High) by passes the resistors and runs directly to the fan via the blower relay. There is NO resistance on the 4th speed.
That means you can pull the fuse or remove the blower relay and the 1st, 2nd and 3rd speeds will still work.
If the fans don't work at all, it is very unlikely (however possible) that both the blower relay and the resistors have failed simultaneously.
It could be...
1) The Blower Inhibit Relay. This relay turns on when the car is started, regardless if the fan is switched on or not.
2) The Fan Switch.
3) The Fan Motor it's self.
4) The BCM.
5) Wiring faults (Shorts etc.).
6) The Blower Fusible Link/s
7) The Main Fusible Link. (That would mean NOTHING on the car would work). Hey, Don't laugh!
8) Fuses.
If only the first 3 speeds aren't working and the 4th speed IS, then yes, it could be is the resistors, the BCM, the fan switch is faulty or faulty wiring.

If only the 4th (High) speed isn't working, then the Blower relay may be faulty, The number 13 Blower Relay Fuse (7.5 amp) VT-VX or The number F22 Demister Fuse (20amp) VZ may be blown (The VZ F22 fuse protects both the Blower and Demistor Relay circuits),
again the fan switch and again faulty wiring.

The HVAC is not really a complicated circuit compared to other circuits on these cars. It's physically finding the fault as you all know is the problem. It's not as easy on more modern cars as it is on older ones. It's just a matter of "process of elimination". Start with the easiest solutions first and then work your way towards the harder ones.

Anyway, I hope this helps anyone with these problems and if there is anyone who can add to this, please do, as it's late and my brain is a bit fuzzy.
 

Nut Kracker

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Probably in need of a re gas.
 

fruity

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How do l replace the Blower fan on a vy commodore and can someone describe "step by step" on how to do it also can l get to it from inside the car and if so from the passenger side or the drivers side. Any advice would be helpful. Thanks
 
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mngrl1

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I know this is an old thread but my VY is also old and the blower fan stopped working. I read all above and tried everything so I was about to buy a another blower fan and I thought I'll just open open the motor and check the brushes. Found the problem! cleaned it all out and put it back together.

Then put it back in the car I was all pumped and then nothing! I was pissed off lol. Opened
20181219_143642.jpg
20181219_144246.jpg
it up again grabbed the multi meter checked the wiring to the brush and it was all good. Put the brushes back in gave them a wiggle tested it on a 12v battery in the shed a VROOM!

All back together now a running like a champ. Just writing in case this helps someone else.
 

Deez76

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THIS "HOW TO" IS ONLY FOR THE MANUAL HVAC SYSTEM AND NOT FOR THE AUTOMATIC CLIMATE CONTROL.

I've been looking around this Forum and I have found that alot of responses as to why the HVAC
(Heating, Ventilation and Air Conditioning) fan is not working, is that the resistors have packed it in.
This is not entirely true.
The fan switch is divided into two parts. Firstly, the lower speeds, 1,2 and 3 run through the resistors to the fan. The 4th speed (High) by passes the resistors and runs directly to the fan via the blower relay. There is NO resistance on the 4th speed.
That means you can pull the fuse or remove the blower relay and the 1st, 2nd and 3rd speeds will still work.
If the fans don't work at all, it is very unlikely (however possible) that both the blower relay and the resistors have failed simultaneously.
It could be...
1) The Blower Inhibit Relay. This relay turns on when the car is started, regardless if the fan is switched on or not.
2) The Fan Switch.
3) The Fan Motor it's self.
4) The BCM.
5) Wiring faults (Shorts etc.).
6) The Blower Fusible Link/s
7) The Main Fusible Link. (That would mean NOTHING on the car would work). Hey, Don't laugh!
8) Fuses.
If only the first 3 speeds aren't working and the 4th speed IS, then yes, it could be is the resistors, the BCM, the fan switch is faulty or faulty wiring.

If only the 4th (High) speed isn't working, then the Blower relay may be faulty, The number 13 Blower Relay Fuse (7.5 amp) VT-VX or The number F22 Demister Fuse (20amp) VZ may be blown (The VZ F22 fuse protects both the Blower and Demistor Relay circuits),
again the fan switch and again faulty wiring.

The HVAC is not really a complicated circuit compared to other circuits on these cars. It's physically finding the fault as you all know is the problem. It's not as easy on more modern cars as it is on older ones. It's just a matter of "process of elimination". Start with the easiest solutions first and then work your way towards the harder ones.

Anyway, I hope this helps anyone with these problems and if there is anyone who can add to this, please do, as it's late and my brain is a bit fuzzy.
Hi I have a HOLDEN COMMODORE VX 3.8L Ecotec LN3/L36 OHV 12v MPFI V6 SERIES 1 4dr Wagon 4sp Auto RWD [10/00 - 07/01] need help with why the Aircon is not blowing hard enough through the vents, it's still blowing a bit of air on 1, 2, 3 and hi but not enough to feel in this 40+ heat up here. Its cold and I can here the blower which sounds a bit loud. Cheers.
 

Freddy1333

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Hi folks - here's my problem: The radiator/condenser fans don't come on when the compressor clutch is engaged. Pressures are ok (checked with gauges) so the system has gas. Cabin fan works as it should. I've swapped relays under the bonnet and checked fuses but no change. If the engine is left to run until the coolant temp is higher then the rad fans DO come on. What's the cause/fix? TIA.
 
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