Aircon pressure sensor?

[mikepday]

Just got the XC70 (p2 2004) back from being re-gassed..... and its still not working.

Fitted a new Condenser and Drier, last week, as it looked like it might have been the culprit. Finally got it gassed and they said "yeah it blows nice and cold, we checked it for leaks, and its fine!"
on the drive home, it felt as though their "blowing cold" was just atmospheric temperature, (6 degrees outside on the dash). compressor clutch doesn't engage either.
stuck it on VIDA and still it shows ECM5000 'Aircon pressure sensor line pressure too low.'
Tested the value and it reads absolutely constantly Zero.
double checked I've refitted the cable to the sensor......and I had.

so now its either
1: lost ALL its pressure on the drive home (no obvious leaks though)
2: they didn't pressurise it .... who knows
3: faulty sensor?

any thoughts? does that sensor part #8623270 tend to fail?

should I be swapping it out? can I test it once its out?

Mike.

[Carlosos]

Originally Posted by mikepday

Just got the XC70 (p2 2004) back from being re-gassed..... and its still not working.

Fitted a new Condenser and Drier, last week, as it looked like it might have been the culprit. Finally got it gassed and they said "yeah it blows nice and cold, we checked it for leaks, and its fine!"
on the drive home, it felt as though their "blowing cold" was just atmospheric temperature, (6 degrees outside on the dash). compressor clutch doesn't engage either.
stuck it on VIDA and still it shows ECM5000 'Aircon pressure sensor line pressure too low.'
Tested the value and it reads absolutely constantly Zero.
double checked I've refitted the cable to the sensor......and I had.

so now its either
1: lost ALL its pressure on the drive home (no obvious leaks though)
2: they didn't pressurise it .... who knows
3: faulty sensor?

any thoughts? does that sensor part #8623270 tend to fail?

should I be swapping it out? can I test it once its out?

Mike.

If it says faulty sensor and the system isnt working is that the first thing to rule out? New sensor then take it from there? Problems like this can be a pig but you’ll sort it.

[stuart bowes]

it may well be the sensor, but point to note, it doesnt say 'faulty sensor' it says reading too low. which could mean pressure is low for other reasons.

I'm not saying it's one thing or the other but always bear in mind fault codes are often just general indicators to point you in the right direction

also you may have fitted the connector correctly but was the cable damaged or a pin dislodged maybe, is there a way of testing the sensor with volt meter set to ohms perhaps, these are the questions I would be asking first

[mikepday]

I know what you mean re DTC codes Stuart, thats why initially I replaced the condenser as that looked like it was going to be the culprit, it had become very tatty after 147000mls in the air flow and system was showing 'ECM 5000' "too low" on VIDA.

however, as I believe the limits for the PX sensor are .2v-5v and 'too low' means that it has next to no pressure in it. I can't remember what the scale read in KPa when I ran the test.

i'd love to know how to test the switch/sensor but electrics are not my Forté.
I do possess a multimeter, but i'll confess to only using it for DC voltage and continuity testing. I do know the sensor has 3 pins one of which must be to ground....... so any clues anyone?

Mike.

[mikepday]

quick thought.

DTC code reads 'signal too low'

it is a 5Volt sensor that measure pressure therefore I presume it delivers its pressure reading as a variable voltage because it's an electric sensor.

therefore one pin is ground one pin is power and one pin is pressure defined output signal? am I right?

can I short two of the pins on the plug to trick the system into believing it has pressure sensed from the sensor?

[stuart bowes]

Sorry it seems I might have been wrong about testing resistance:

a bit more info here

https://www.matthewsvolvosite.com/fo...ic.php?t=39041

but I suppose that doesn't really help if you're not sure pressure is actually good or not.

maybe pop back to the aircon guys or give them a call and ask if they don't mind just double checking for you or showing you the pressure on their gauge

fingers crossed someone with more knowledge will come along with some other suggestions