Heating system

[nelmo]

Over the last couple of months, the heater in my car just hasn't worked properly; it would get warm but as soon as you turned the fan on, it went cool again. Was wondering what to do when the 12v Battery died (incredibly suddenly - working one day, 2 days later, absolutely dead).

It looked like the original 13 year old Battery, so it did well 🙂

Bought a new one and, shazam, the heater is working properly! 😮

Can anyone explain to me how the 12v Battery affects the heating system? 

[Herbie]

45 minutes ago, nelmo said:

Can anyone explain to me how the 12v battery affects the heating system? 

No, but I'd like to know too.

In theory, it shouldn't. The 12V Battery in any car, conventional or hybrid, is only used to start it. Once the engine is running/READY light on, the alternator (or DC/DC converter) then supplies the whole electrical demand of the car and keeps the 12V Battery topped up, so the 12V Battery shouldn't even be in the equation.

[nelmo]

Urgh, false dawn - just been on first drive for a few days and heating back to rubbish. Must have been wishful thinking.... 

I guess the question now is "why is my heating not working?" 

Engine temp is fine, fan blows air out so it's not blocked ducts... 

[Greisingel]

Rx400h?  Make sure your rad isn’t leaking. make sure you don’t have a coolant air lock. Thermostat? Maybe. Heater core may need a clean. So flush and clean and flush main rad then use Toyota recommended coolant pink or red 

[nelmo]

I did have a strange issue back in August - we went to France on holiday (remember those? 🙂 ) and the temperature gauge moved above halfway for the first time in the 7 years I've owned the car. I couldn't see any obvious issue although the coolant level had dropped a little. I added more coolant and I've not had the issue since. It was hot in France, so I assumed the coolant had just escaped somehow (is there some sort of overflow?).

I guess a coolant change may be a good idea anyway, not been done for a long time (I'm not very kind to the old dear)...

So on another trip out, I get heat if the engine is running but nothing when it goes off and I'm on electric - has it always worked like that maybe? I really haven't noticed that before but....

[Greisingel]

57 minutes ago, nelmo said:

I did have a strange issue back in August - we went to France on holiday (remember those? 🙂 ) and the temperature gauge moved above halfway for the first time in the 7 years I've owned the car. I couldn't see any obvious issue although the coolant level had dropped a little. I added more coolant and I've not had the issue since. It was hot in France, so I assumed the coolant had just escaped somehow (is there some sort of overflow?).

I guess a coolant change may be a good idea anyway, not been done for a long time (I'm not very kind to the old dear)...

So on another trip out, I get heat if the engine is running but nothing when it goes off and I'm on electric - has it always worked like that maybe? I really haven't noticed that before but....

Snap. August 2019. Southern France. 40°C ambient heat. It was brutal. AC on full time  

Car always ran temp gauge dead centre. Then original rad blew. Had to drive 50 miles to holiday destination on Battery, downhill recharge and short engine burst. Thank god for wide French road verges and no hedgerows  

Changed new Denso rad back home. Holds water ok and temp needle sits just over halfway55%. 

One more flush and clean and full Toyota coolant should put needle bang on centre I hope