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Heating blowing cold when stop/start kicks in


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Hi all, I’m new here 😀

I have a 16 plate Ford Focus Titanium and have recently noticed that when the auto stop/start kicks in at traffic lights etc the heating cools off and then starts blowing cold air, I’ve asked the garage about it and they have told me that is the way it works, but feel like I’m getting fobbed off.  

It was doing the same during long journeys even when the stop/start wasn’t kicking in during motorway travel, so the garage looked at it and told me they found a leak and fixed it, but they are still adamant that the heating will always cool off when the stop/start kicks in.

I’ve had the car nearly a year but I thought when I was using it last winter that when the air started to cool the auto stop/start re started the car automatically to keep the heat up. 

Am I right in my recollection and therefore there is something wrong with it at the moment or is what the garage telling me correct?

Keen to find out as it’s only got a few more months left on its warranty 👍🏼

Any advice greatly received,

Cheers K

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Aye - it does sound a bit iffy...

Obviously, the air is warmed by the engine coolant, so stands to reason that when the engine is off, it won't be as warm.  But, I would expect that the air should stay warm for a few minutes after engine-off.

Unless the coolant isn't particularly warm to begin with - which could be an indication of a failed thermostat.  Or possibly an airlock in the coolant system.

Does the engine temperature appear normal? (Not sure how it's setup on the Focus - I know some cars have the temp run the ECU, so they display cold, normal or too hot, nothing in between).  

Is the air as hot as you'd expect when it is running?

Any strange gurgling sounds from behind the dash?

With the bonnet up, and engine warm, are the coolant hoses all similar temperatures to the touch? (Usually big rubber hoses).  With a cold engine, it may also be worth giving them a squeeze - you might feel/hear if there's any air in them.

My only experience with dodgy car heating was on a Mk2 Punto with the notorious 1.2l FIRE engine.  It went through thermostats almost as quickly as headgaskets....

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if the heater fan is on but the engine is not running I would think the air would cool very quickly as the hot water is not being circulated by the water pump so the stationary water in the heater matrix will cool very quickly with the fan on.  Unless Ford have designed it with an electric water pump which keeps the water flowing round when the engine is not running in which case I would think it would pump out heat a lot longer - they might have done that, I can't keep up with what new fangled things the makers do these days

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Thanks for this folks, I’ll check out your suggestions tomorrow SeanW but I can’t say I’ve noticed anything unusual. I guess I might be making more use of the off button for the stop/start 😂

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