AC gradually loses power

ICE, Equipment, Options
bluepurple
Posts: 5
Joined: Mon May 31, 2021 8:05 pm
Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by bluepurple »

I wonder if anyone can help here with an AC issue on our 2014 1.2 QQ.

The car seems to cool, perfectly for around 30mins then gradually the blowers emit less and less air until there is almost no air coming from the vents. Was about 25C outside so fairly warm, and we were cruising on the motorway.

The air is cold, and the fan sounds as though it is working really hard.

Any suggestions here please? I have trawled the site and I cannot see anyone has had a similar issue. I considered replacing the blower transistor, but this does not sound like my issue.

It must have gas as it cools perfectly for the first 30mins...

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gloucester
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Location: Gloucestershire, England
Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by gloucester »

Welcome to this forum

Haven't a clue - is the restriction the same irrespective of whether the distribution is set to screen, face or feet?
(2015 Nissan Qashqai Tekna DIG-T 1.2 sold 15/6/18) ~ 2018 Suzuki Ignis SZ5 - 2018 Yamaha MT-07 ~ (2024 Volvo EX30 ordered)
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calnorth
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Qashqai Model: Mk.2 Qashqai Facelift - J11b (2017–2021)

Post by calnorth »

bluepurple wrote: Mon May 31, 2021 8:11 pm I wonder if anyone can help here with an AC issue on our 2014 1.2 QQ.

The car seems to cool, perfectly for around 30mins then gradually the blowers emit less and less air until there is almost no air coming from the vents. Was about 25C outside so fairly warm, and we were cruising on the motorway.

The air is cold, and the fan sounds as though it is working really hard.

Any suggestions here please? I have trawled the site and I cannot see anyone has had a similar issue. I considered replacing the blower transistor, but this does not sound like my issue.

It must have gas as it cools perfectly for the first 30mins...
Can we assume the heating is working ok? All outlets blowing well.
Mk2 Qashqai Facelift - J11b (2017–and onward)
1.6 Dig-T N-Connecta
Qashowner
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Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by Qashowner »

Have you got it set to auto? That would have the same effect, the blowers will pump hard and then slow as the set temperature is reached.
Past cars Mercedes B Class, S Class, E Class Estate, E Class Coupe, G Wagen, 260E interspersed with Peugeot 406 and Audi Coupe.
bluepurple
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Joined: Mon May 31, 2021 8:05 pm
Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by bluepurple »

Thanks for the responses thus far.

The system is not set to Auto. The same restrictions is apparent whether routed to windscreen, face or feet. I do not think there is an issue when blowing hot either.

Forgot to add that I replaced the cabin filter a few weeks back, but the issue was there prior.

Keep the suggestions coming!
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calnorth
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Qashqai Model: Mk.2 Qashqai Facelift - J11b (2017–2021)

Post by calnorth »

From what you say the the Fan appears to be driven against the main air flow path that becomes closed.

However, the Fan also has to pull air in through motorised inlet air doors for an intake air mix.

Can you press the Re-circulation button (intake air) to see what happens. Does pressing it ON/OFF change anything and which it normally would. Do it at start of a journey and when air flow becomes slowed as you describe.
Mk2 Qashqai Facelift - J11b (2017–and onward)
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bluepurple
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Joined: Mon May 31, 2021 8:05 pm
Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by bluepurple »

calnorth wrote: Wed Jun 02, 2021 7:58 am From what you say the the Fan appears to be driven against the main air flow path that becomes closed.

However, the Fan also has to pull air in through motorised inlet air doors for an intake air mix.

Can you press the Re-circulation button (intake air) to see what happens. Does pressing it ON/OFF change anything and which it normally would. Do it at start of a journey and when air flow becomes slowed as you describe.
Thanks for the suggestions - I tried these things and they seemed to make absolutely no difference... I am leaning towards an electrical/sensor issue. I may bite the bullet and see if an AC specialist can figure it out.
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calnorth
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Qashqai Model: Mk.2 Qashqai Facelift - J11b (2017–2021)

Post by calnorth »

The AC (Climate) function is simply pairs of air flow adjustment doors either side of the Fan blowing through the evaporator/heater matrix. Mostly electronically controlled by an AC Amplifier module and driving a Fan speed MOSFET speed controller. The AC Amplifier receives all sensor/user demand inputs and adjusts as required.

There are approx 10 error codes (DTC) that are available for various component faults (sensors/Comm etc). Diagnosing without them is very difficult IMO.
Mk2 Qashqai Facelift - J11b (2017–and onward)
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bluepurple
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Qashqai Model: Mk.2 Qashqai - J11 (2013–2017)

Post by bluepurple »

calnorth wrote: Thu Jun 03, 2021 9:41 am The AC (Climate) function is simply pairs of air flow adjustment doors either side of the Fan blowing through the evaporator/heater matrix. Mostly electronically controlled by an AC Amplifier module and driving a Fan speed MOSFET speed controller. The AC Amplifier receives all sensor/user demand inputs and adjusts as required.

There are approx 10 error codes (DTC) that are available for various component faults (sensors/Comm etc). Diagnosing without them is very difficult IMO.
Indeed I am suspecting an electrical fault somewhere - maybe a job for an auto electrician rather than an auto AC engineer.

Would I be able to pull any stored codes myself? I am not familiar with the process of scanning newer vehicles. I do have an OBD tool somewhere...
lewisbryant
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Joined: Sat Feb 23, 2019 7:27 am
Qashqai Model: Mk.3 Qashqai - J12 (2021+) New Model

Post by lewisbryant »

Does the air restriction only happen when the AC is on? Does it happen after 30 minutes with AC off? Only reason is that I've seen a car before not nissan where the evaporator has frozen up solid with ice and blocks the air flow

This is usually caused by a faulty evaporator temp sensor as this sensor when it gets to 3 degrees it shuts the AC pump off and as it warns up to about 7 or 8 degrees it turn the AC back on

If the Auto amp is reading say ambient temp then it will keep the ac pumping and it will cause the evaporatof to freeze and block up with ice causing low airflow

You can check this temp sensors reading with a scantool communicating with the hvac module
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