Heater problem

[Gary Lindsay]

The problem I've got is that my heater comes on when it's switched off the engine fan cools down the engine on and off for over a couple of hours, draining tge battery, has anyone had this problem and whst was the fix? Thanks in advance. 

[Magnet]

Thanks Gary, but I’m having a little difficulty in understanding how the ‘heater comes on’ - when the car is switched off and the engine isn’t running. 
Could you please explain further, and break it down to exactly what happens and when - ? 
Kind regards,

Gareth. 

[cliffcoggin]

Gary. Are you saying the cabin fan runs as well as the engine fan?

[Gary Lindsay]

Yes the cabin fan comes on, on it own when switched off for a about 5mins on start up the goes off for about 30secs then comes back on. The engine fan works but when I've switched it off it runs on for a couple of hours running the battery down.

Any help would be appreciated as costs can quickly sore.

[Gary Lindsay]

On 8/7/2024 at 8:41 AM, Magnet said:

Thanks Gary, but I’m having a little difficulty in understanding how the ‘heater comes on’ - when the car is switched off and the engine isn’t running. 
Could you please explain further, and break it down to exactly what happens and when - ? 
Kind regards,

Gareth. 

Thanks for your reply, maybe I wasn't clear in my question, I'll start over, when starting the car the cabin fan comes on and it's switched off, it goes for about 5mins the switches off for about 30secs then comes back on, still switch off. The engine fan is working but when I switch it off the engine fan runs for a couple of hours running the battery down. I've no idea how to fix the problem so any help would be appreciated as costs can sore.

[cliffcoggin]

The only single fault I can imagine that would allow both the engine fan and the cabin fan to continue running would be a failure of the ignition switch to interrupt the power supply when turned off, unlikely though that seems. Are there any other circuits, such as radio and lights for example, that are still operating when they should not be?

[Magnet]

Thanks Gary,

For me to get my interpretation correct:- 

When you say the heater comes on, you actually mean the heater fan comes on - yes? 
Is the symptom any different if the heating is set to ‘Auto’, or indeed the whole system switched off -if possible? 
Any different if switched to air con? 
Any different if switched to fast demise/defrost? 
Just to get the full story:- does the coolant temperature reach 90 degrees in a sensible period of time - say 3 miles - and constantly holds steady at that? 
Kind regards,

Gareth. 

[Gary Lindsay]

7 hours ago, Magnet said:

Thanks Gary,

For me to get my interpretation correct:- 

When you say the heater comes on, you actually mean the heater fan comes on - yes? 
Is the symptom any different if the heating is set to ‘Auto’, or indeed the whole system switched off -if possible? 
Any different if switched to air con? 
Any different if switched to fast demise/defrost? 
Just to get the full story:- does the coolant temperature reach 90 degrees in a sensible period of time - say 3 miles - and constantly holds steady at that? 
Kind regards,

Gareth. 

The heater fan comes on in the cabin when heater is switched off no lights on the unit totally switched off but the fan inside the car will run for abou 5mins, go off for like 30 secs then comes on again until I switch the ignition off. Switching the engine off the engine fan kicks in and drains the battery, on a normal drive the temp gauge reads normal, air con is ok too, when the cabin heater is on, everything works as it should just these two faults. 

On 8/7/2024 at 8:41 AM, Magnet said:

Thanks Gary, but I’m having a little difficulty in understanding how the ‘heater comes on’ - when the car is switched off and the engine isn’t running. 
Could you please explain further, and break it down to exactly what happens and when - ? 
Kind regards,

Gareth. 

Thanks for your reply, maybe I wasn't clear in my question, I'll start over, when starting the car the cabin fan comes on and it's switched off, it goes for about 5mins the switches off for about 30secs then comes back on, still switch off. The engine fan is working but when I switch it off the engine fan runs for a couple of hours running the battery down. I've no idea how to fix the problem so any help would be appreciated as costs can sore.

[Gary Lindsay]

21 hours ago, cliffcoggin said:

The only single fault I can imagine that would allow both the engine fan and the cabin fan to continue running would be a failure of the ignition switch to interrupt the power supply when turned off, unlikely though that seems. Are there any other circuits, such as radio and lights for example, that are still operating when they should not be?

It's only the engine fan that comes on after switching the ignition off, the cabin fan comes on completely switched off no lights on the unit, when switched on the cabin heater works as it should air con ect, switch it off and the fan keeps running at the same temperature and won't switch off until I pull the ignition 

[cliffcoggin]

Gary.

I am not sure I completely understand the problem even now, so let me summarise the symptoms as I read them.

[1] The engine fan continues to run after switching off the ignition and removing the key. Correct?

[2] The cabin fan runs when the fan switch is in the OFF position and the ignition is switched on, but when the ignition is switched off the cabin fan stops. Correct?

We need to properly understand the problem before suggesting a solution.