Author Topic: Heater  (Read 270 times)

X25DJB

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Heater
« on: January 24, 2023, 09:03:58 PM »
Hi, I have a 2014 petrol hybrid, with which I am pretty pleased. An annoyance, particularly in this weather is that the heater doesn't get very warm, and it takes ages to blow hot.
Anyone else suffered from similar?
Could it just be a jammed main engine thermostat?

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Jocko

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Re: Heater
« Reply #1 on: January 24, 2023, 09:16:40 PM »
It could be, but looking at your annual mileages do you ever go far enough to get it warmed up? Does the blue light on the instrument panel go out? In the winter, from my own experience, it takes about 7 or 8 miles before the engine is fully up to temperature.

X25DJB

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Re: Heater
« Reply #2 on: January 24, 2023, 09:20:47 PM »
Thanks, I'm a little over 12,000 annual mileage. The car only had 7,000 when I bought it. Yes the blue light goes off within a mile, and my usual trip is 12 miles.

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Jocko

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Re: Heater
« Reply #3 on: January 24, 2023, 10:47:59 PM »
Okay. You have recently got the car. The previous owner didn't use it much. I trust the coolant level is fine.
The thermostat could be stuck open or the heater valve may not be opening fully. Do you have climate control or a manual heater system? I know with the manual system it is possible for the cable to slip but I do not know how the climate control governs the temperature.
I have a ScanGauge E that plugs into the OBD II port and actually tells you how hot the coolant gets.

X25DJB

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Re: Heater
« Reply #4 on: January 24, 2023, 11:06:45 PM »
Yes that's right. I am due a service and MOT very soon will get the thermostat checked, that was my first suspicion too. Is the plug in that you have expensive? I'm pretty sure that the coolant level is correct.

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Jocko

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Re: Heater
« Reply #5 on: January 25, 2023, 08:05:17 AM »
The ScanGauge E was fairly expensive but you can get a Bluetooth dongle and an app for a smartphone that does similar.

X25DJB

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Re: Heater
« Reply #6 on: January 25, 2023, 08:14:54 AM »
Thanks I'll Google that

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orangeTomato

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Re: Heater
« Reply #7 on: January 29, 2023, 10:17:21 AM »
How cold is cold? If the air is just "medium-warm" as opposed to "not heating up at all", the engine might not be loaded heavily enough to generate enough heat through your entire journey.

My mk3 jazz (non hybrid, of course) never really blows hot at this time of year if it's working at light load. The engine just isn't generating enough heat and the cooling system will sacrifice interior temperature to keep the engine warm.

So that's conditions like driving around town or keeping a steadyish 40mph on a flat country road (not much load, lots of cold outside air passing through the engine bay).

If you're confident that you're not losing coolant, I'd suggest  bringing it up to 70mph on a motorway, or finding a hill to drive up. That'll make the engine work a little bit harder, and if the air starts blowing properly hot, there's probably not too much to worry about,
« Last Edit: January 29, 2023, 10:21:19 AM by orangeTomato »

X25DJB

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Re: Heater
« Reply #8 on: January 29, 2023, 10:27:08 AM »
Thanks very much. I had never considered that. Obvs in today's fuel market I am driving as economically as possible.

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Jocko

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Re: Heater
« Reply #9 on: January 29, 2023, 02:38:17 PM »
I always got hot air out of my Jazz's heater after the blue temperature light went out. Didn't matter how cold it was outside or whether I was driving in the city or just pootling along on a country road. It had a brilliant heater. Enough to be uncomfortable against my leg unless I turned it down a bit.
I do realise that the Mk 4 is a different kettle of fish but I would have imagined the Mk 3 would also provide plenty of heat.

Kremmen

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Re: Heater
« Reply #10 on: January 29, 2023, 02:51:10 PM »
I spent many years driving the same 20 mile route to work in many cars.

My 8G and 9G 1.8 petrol Civics, I knew exactly when warm air started to trickle out with a slow fan speed and where I was when it was pumping out proper heat with a high fan speed. Set to Auto at 22C.

I drive the same route fairly often now and I've noticed the Mk4 pumps out warm and proper heat sooner which surprised me....but I'm not complaining :)
Let's be careful out there !

orangeTomato

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Re: Heater
« Reply #11 on: January 29, 2023, 03:46:07 PM »
My MK3 definitely heats up faster than my previous Vauxhall Meriva but it had the same steady state characteristic: Under steady state light load, it would prioritize maintaining constant coolant temperature over cabin heat. For over a year my commute had mindnumbing 20 mile section of 50mph roadworks on the motorway.

To stave off boredom on a cold day I shoved a cheap thermometer in an air vent and measured coolant termperature via OBD2. The air vents dropped way down from the normal 85-90 degrees (hotter than you'd think!) but the OBD2 collant termperature didn't budge from its usual ~105ish setpoint. There was always  noticable blast of heat after the end of the roadworks, usually within 20-30 seconds or so of putting my foot down.

Fairly sure my mk3 is similar. My commute starts in town and the air never really gets hot. But once I hit the first A-road there's a similar whoosh of heat not long after I hit 60mph. It's fairly understandable from a kinetic-energy perspective -- energy squares with speed, so one 0-60 acceleration will have burnt the same fuel as several 0-30 accelerations.

I suspect that the car designers probably have some "compromise" operating regime in cold temperatures, where the interior is allowed "a bit" of heat  even at the expense of the engine. While waiting around one cold day in my Meriva, I discovered that at approximately -5 degrees, I could make the coolant gauge dip slightly by putting turning the blower speed to max. When I turned the blower down the gauge went back to normal.

If so, I'm guessing the mk2-hybrid/mk3-normal jazz (cooling system probably very similar?) might have 3 operating modes:
1)  After a cold start: Heat up enging block at all cost (fast idle, rich mixture, blue dashboard light)
2) When block/collant above acceptable minimums: Circulate some hot coolant to the heater matrix but prioritize the engine
3) When enough heat to go around: Cabin can be as hot as it wants.
And I guess that, under light load conditions, sometimes it's possible to never exit mode 2)


PS: Other factoids about my Meriva
* When driving at 50mph in an average speed camera area, wiggling the steering wheel left and right would trigger an ABS fault
* If you selected maximum heat and closed all the heater vents, a burning smell would come from the dashboard (probably also discovered while driving straight and flat at 50 mph...)
* The Meriva was a mini MPV built off Corsa mechanicals. Vauxhall/Opel didn't use a beefier gearbox to cope with the car's added weight, so its first gearbox only lasted 65k miles
* Unlike most lazy modern B-crossovers (Looking at you, HR-V), the Meriva had a well-designed and totally bespoke interior that used up all the interior space. If you consider a jazz to be a supermini-TARDIS, the Meriva was more of a C-segment-TARDIS. With the rear seats down, rear interior volume was larger than a Passat estate!
* I suspect that most interior testing/validation was done with the Opel variant, as the chromed Vauxhall logo in the middle of the steering wheel reflected too much light into my eyes on a sunny day.

PS2:
I've noticed the Mk4 pumps out warm and proper heat sooner which surprised me....but I'm not complaining :)

I don't have one so I'm just guessing, but I wonder if the traction battery can usefully absorb some additional energy from the engine right from the get-go, as opposed to normal transmissions which
1) have to maintain drivability during initial warmup
2) can't absorb excess energy while idling (i.e there's only so much fuel you can burn without the revs shooting sky high)
« Last Edit: January 29, 2023, 04:02:18 PM by orangeTomato »

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