Confirm that AC Pressure sensor is the culprit

[JRL1500]

New member, first post.

Just bought a 2009 Nissan Rogue S AWD for my son, 145K on the clock. Decent little car, doesn't have to be great, he only lives 2 miles away from work, but it DOES need to have A/C...we live in the Deep South. Full disclosure, bought the car knowing the A/C wasn't working, but believe it's a reasonably easy fix.

Before purchase, pulled a vacuum on the car with the automated system we have at work for truck maintenance. Vacuum held fine. Refilled the system with the prescribed amount, hoped the system was just low, no luck, compressor won't engage. Jumped it at the compressor and it engaged, car blows cold, so know compressor is good. Tested IPDM, you can hear the compressor "clunk", which I assume will rule out all fuses and relays. Not sure if that rules out the amplifier or not, honestly, first time I've heard that term used with an A/C system. Panel lights come on, A/C light illuminates on the panel, assuming we're good there.

I read through the posts I could find here, my guess is the pressure sensor in front of the radiator is bad. Full disclosure, they replaced the radiator before I bought the car, so literally JUST now thinking they could have damaged the harness. Helps to type it out sometimes.

Based on what I've said so far, is Pressure Sensor the way to go? Feel like the rest of the system has checked out, but was hoping to get a second opinion.

Thanks all!

[VStar650CL]

The pressure sensors are pretty easy to test (although getting at them to test can be a chore). They always flatline at 0V when they fail. The ECM is what reads the signal, so if you have a scanner which will support streaming the A/C pressure, just have a look at the voltage. Static pressure should be around 1V, and a good sensor will never read 0V. Even when the system is empty, you'll get something like 0.1V. If you need to test it with a voltmeter, back-probe the middle wire (Yellow) with a small safety pin or t-pin. To check power, with the connector loose and the key on you should show 5V between Blue and White and from Blue to ground. If you read 0V on both then the power wire is compromised, if Blue reads 5V to ground but 0V to White then the ground wire is compromised. You can find complete info on the A/C control system here:
https://www.nicoclub.com/service-manual ... %2FHAC.pdf

Two other things which can cause compressor no-op are the Ambient temp sensor in the grille and the Intake temp sensor on the evaporator. If either one goes open-circuit (5V reading) the HVAC will think the car is in Siberia and won't let the compressor turn on. The Ambient is easy to check, it's the outside temp reading in the cluster. IIRC the Intake sensor connector on the gen1 Rogues is on the glove box side of the HVAC. The easiest way to check that is to short the signal wire to ground and see if the compressor kicks on (0V tells the HVAC the car is in the Sahara).

[JRL1500]

Thank you!

So, sounds like the last two sensors are super easy to check. If car reads ambient temp on cluster, then that one is good. If shorting intake temp sensor to ground engages clutch, then it's bad. Those seem easier to check first before getting to the pressure sensor.

I don't have a scanner that will read that data, one of the Techs at work does. He'd checked it initially (pre-purchase) and said that he didn't see any issues with fuses and relays. That's what lead to us thinking maybe it was low pressure. I'll see if that's something he can read before trying to manually probe the pressure sensor.

[VStar650CL]

The Intake sensor is easy to check but not so easy to fix, the connector is external but the sensor itself is stuck to the evaporator fins and requires removing the HVAC box to change. The car has a TXV Valve so it's usually okay to just short it permanently, but if you start getting evap freeze-ups on humid days then you'll need to bite the bullet and change it.

[JRL1500]

On the ambient temp sensor, do all the trim levels have that? Thought I'd read elsewhere on this forum that the SL had the ambient temp sensor but on the S, the connector was there but it wasn't shipped with a sensor.

[VStar650CL]

If it doesn't show up on the dash display then it doesn't have it. The cluster software is different on ones that don't have it, so if there's no display then there's no sensor either.

[JRL1500]

Posts in this forum helped me troubleshoot the basics, pointed me in the right direction, and VStar650CL filled in the specifics. That sent me looking for the Pressure Sensor at the front of the radiator, which now that I think about it, the seller mentioned they'd just replaced... I went looking for a wire that they may have hit/cut, instead I found that the shop hadn't plugged the sensor back in. Snapped it down, A/C is working!

Huge thank you VStar650CL and this forum in general!

[VStar650CL]