Refrigerant pressure sensor bypass?

Post your Cit/Peu/Ren air conditioning queries or advice.

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Refrigerant pressure sensor bypass?

Post by teuski » 09 May 2016, 16:43

I had my '96 Safrane's aircon filled but it still doesn't work. At least there weren't any major leaks and the machine decided it was ok to refill.

The AC text appears on screen when requested, but when it's warm enough for it to start there appears "service" text too and the compressor never engages.

My CLIP tester gives "circuit open" faults on "refrigerant pressure sensor circuit" and "water temperature sensor circuit" which i can't just erase. The injection ECU has correct water temp and my gauges work too.

The pressure sensor is of 3-wire type with red, black and yellow(?) wires. Should i have something measureable on the open connector? Is there a way to try bypassing the sensor to see if it makes a difference?
Is there a way to measure the sensor itself? Looks quite challenging to get probes on the pins...

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Re: Refrigerant pressure sensor bypass?

Post by spider » 11 May 2016, 09:18

I'd expect it to be a variable sensor rather than a simple 'switch' type.

You should be able to get a resistance reading from it at least, even with the connector unplugged just measuring the resistance (may have to try combinations as its three pin)

The compressor won't engage if it thinks there is not enough refrigerant pressure to prevent damage.

You've had the multiplug off to check its not just got a bit of corrosion in it yes ?

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Re: Refrigerant pressure sensor bypass?

Post by xantia_v6 » 11 May 2016, 13:20

Try setting the system for defrost, as that should automatically bypass the water temperature sensor to narrow things down a little.