Heating fan intermittent/not working

[Red Car]

Looking for help/suggestions.

I have had my MG4 for 18 months with no problems.

Last week the heater became intermittent- just switched itself on and off randomly.

Today the heating works for about 3 seconds, then switches itself off and does not work at all including the front windscreen demist. The buttons below the main screen are lit up as though it is on, but nothing happens.

I have asked our local MG garage to look at it but they say they have never heard of the problem and can’t look at it until at least next week. Problem is, it mists up and I can’t see where I am going.

I have done a reset button pressing the Home Screen button and also left it locked and retried several hours later but it still isn’t working. Then we disconnected the 12v battery. Preheat from the app also doesn’t work - the car lights up and the fan light comes on, but the fan doesn’t come on.

Any suggestions please? Has anyone else had this problem and found a solution?

 

[bedsev]

So when your demist (2nd button) is on, does it do the same?

 

[pecker]

Have you checked the fuse ?

 

[Red Car]

So when your demist (2nd button) is on, does it do the same?

Yes it does. The fan does not come on, but if I leave it in, it occasionally comes on for a few seconds and then switches off again on its own accord.

Have you checked the fuse ?

I don’t think it is the fuse as the fan comes on very intermittently. If the fuse has gone surely it wouldn’t work at all?

 

[Bricktop X PWR]

The dealer saying they can see you next week is a right result.

Some folk are put off for weeks/months!!!

You'll just have to crack open both front windows when your on the move to stop it misting up til you get it fixed.

 

[Lovemyev]

Not sure with regards to the system used on the MG4, but the similar problem of lack of heater fan blower, has been attributed to the resister pack failure on the ZS EV models.
This resistor pack controls the speeds produced by the 12 volt heater fan blower motor.
Depending on the design on certain units, it can completely fail, or intermittently turn the fan on or off.
This is caused as the load increases and the resistor and it breaks down, when it is allowed to cool down, it will work again briefly.
Depending on the design of the unit, it can only affect the lower speeds, but it will still work on the top setting as a safe guard.
I this happen on a BMW 3 series I had a long time ago.
No fan on speeds 1 to 4, but on setting 5 it by passed the resistor altogether, for full power.
This method of using an in line resistor, is used widely on heater units on mainy different models, including ICE and EV’s.
But they will vary in design and how they fail of course.
I will try and include a photo of the unit / pack used on the ZS EV models.

 

[gdog]

Not sure with regards to the system used on the MG4, but the similar problem of lack of heater fan blower, has been attributed to the resister pack failure on the ZS EV models.
This resistor pack controls the speeds produced by the 12 volt heater fan blower motor.
Depending on the design on certain units, it can completely fail, or intermittently turn the fan on or off.
This is caused as the load increases and the resistor and it breaks down, when it is allowed to cool down, it will work again briefly.
Depending on the design of the unit, it can only affect the lower speeds, but it will still work on the top setting as a safe guard.
I this happen on a BMW 3 series I had a long time ago.
No fan on speeds 1 to 4, but on setting 5 it by passed the resistor altogether, for full power.
This method of using an in line resistor, is used widely on heater units on mainy different models, including ICE and EV’s.
But they will vary in design and how they fail of course.
I will try and include a photo of the unit / pack used on the ZS EV models.

View attachment 34396

I recall bodging one of these many years ago on an MG TF by soldering in a new resistor from "maplin" (about 50p lol) to replace the failed resistor. They are usually located in the ventilation ducting, for cooling. worked a charm. Probably not possible nowadays

 

[PeteC]

I recall bodging one of these many years ago on an MG TF by soldering in a new resistor from "maplin" (about 50p lol) to replace the failed resistor. They are usually located in the ventilation ducting, for cooling. worked a charm. Probably not possible nowadays

I did the same thing on an old MX5.

 

[Red Car]

Not sure with regards to the system used on the MG4, but the similar problem of lack of heater fan blower, has been attributed to the resister pack failure on the ZS EV models.
This resistor pack controls the speeds produced by the 12 volt heater fan blower motor.
Depending on the design on certain units, it can completely fail, or intermittently turn the fan on or off.
This is caused as the load increases and the resistor and it breaks down, when it is allowed to cool down, it will work again briefly.
Depending on the design of the unit, it can only affect the lower speeds, but it will still work on the top setting as a safe guard.
I this happen on a BMW 3 series I had a long time ago.
No fan on speeds 1 to 4, but on setting 5 it by passed the resistor altogether, for full power.
This method of using an in line resistor, is used widely on heater units on mainy different models, including ICE and EV’s.
But they will vary in design and how they fail of course.
I will try and include a photo of the unit / pack used on the ZS EV models.

View attachment 34396

Thanks for the information. Hopefully it is this!

 

[DixieTGS]

Also worth checking for why it may have failed. In my case on a Focus, the fan motor was beginning to seize. This in turn was caused by water running in down the air duct, and that was caused by the pollen filter being replaced at service by bending the cover up instead of unclipping properly. It sounds involved, but was actually just a couple of hours to diagnose and fix.