AC gradually loses power

[calnorth]

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

See if the Compressor is running (clutch) at the problem point:

CONTROL BY A/C AUTO AMP. (from diagnostics)
Low Temperature Protection Control
When intake sensor detects that evaporator fin temperature is [−5.0°C (23.0°F)] or less.
A/C auto amp. requests ECM to turn the compressor OFF, and stops the compressor.

When the air temperature returns to [1.0°C (33.8°F)] or more, the compressor is activated.

The intake/Evap temperature sensor measurement range is from -20C thru +40C in 10C steps (degrees).

I'd of thought if the Evap was freezing up at some point a puddle would appear under the car?

[bluepurple]

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

Great, this is something to investigate. Do you have a suggestion for a scan software? I managed to hook up my obd tool and download a piece of PC software, but I could not seem to communicate with the HAC.

[lewisbryant]

No I don't know of any software that will work with a generic obd tool, I use consult 3 plus

[calnorth]

Generic ODB devices on the market and manufacturer specific tools (eg Nissan Consult) receive data from the ECU regarding DTC's (error codes).

Many of the generic tools are Chinese knock offs with invalid or out of date software and as such will not fully resolve all manufacturer DTCs. You likely need a Nissan dealers help here.

[ISwift]

I have the same problem. However, the data for the evaporator sensor is not available on the OBD2. I would to test and replace the evaporator temperature sensor. Is there any advice on how to do the replacement?

[pedrocampos927]

hello
any solution on this topic?
i have a similar problem, last week go on a trip and after 2hours on AUTO settings on 22º and start to feel hotter and hotter and see that blower is very weak.
turn off the AUTO setting and manually put to glass and front blowers on max and lowest temperature and ear the blower on max noise but very low air from the vents (cold but very weak).
its on a 2015 j11 1.6 dci

[Pandjh]

For me the solution was a leak check (none found) and an expensive regas. I was inexplicably down to 110g of gas from a starting point of 500g and it would start OK and fade over time.

[Mbqashqai]

Was is confirmed that the evaporator temperature sensor was thr issue in the end? As I have the same issue, ac if working fine until a after a while and then it gradually loses its cold air and flow.

If the evaporator temperature sensor was the issue. Is this a replacement that can be done at home? Are there any guides/videos on where to locate the sensor?
Thanks!

[Gman1981]

Hi. I have this problem. Did you find the fix. Mine is really cold and then after 2 hours it gets warmer and the air seems restricted. Park up for half an hour then its ok. I believe its freezing up. Ive been told it could be the evaporator temperature sensor. But not sure where this is located.
Any advice would be appreciated.

[andy2019]

Have you got auto temp on ?