A/C low pressure sensor/switch location

KTHEBUM

MEMBER
2010 FORD ESCAPE
2.5L
4 CYL
2WD
AUTOMATIC
150,000 MILES

Where is the A/C low pressure sensor/switch located, and can it be replaced without opening the A/C system? I just replaced most of the major components in my A/C system, drew a vacuum, and attempted to add refrigerant, but the compressor clutch wouldn’t engage even though the low side was above 30 PSI after I added some refrigerant. Compressor/clutch are brand new and I confirmed the electrical wiring/attachment to the compressor work (tested the relay and also bypassed the relay for a few seconds just to confirm the compressor/clutch would engage - it did). So it seems some kind of sensor is preventing the PCM from allowing power to go to the compressor clutch. Wondering if it’s just a bad low pressure switch. If you have any other thoughts about what the problem could be I am all ears!

Monday, April 27th, 2020 AT 9:52 PM

5 Replies

ASEMASTER6371

MECHANIC
52,796 POSTS

Good morning,

There is a 3 wire pressure sensor I attached for you to view on the dryer. That is the pressure sensor.

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

You need to verify a 5 volt reference signal to the sensor with the AC in the on position.

There are also 2 fuses you need to test for power on both sides as well to be sure power is being sent to the relays.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Are you using a machine to install the Freon?

I attached a wiring diagram for you to view of the system.

https://www.2carpros.com/articles/how-to-check-wiring

Roy

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Tuesday, April 28th, 2020 AT 3:57 AM

KTHEBUM

MEMBER
16 POSTS

Thank you. Is that the only pressure switch on the whole system? I thought I saw somewhere that there may be another low pressure switch somewhere by the lines to/from the evaporator, but it's hard to find good information. The dryer is brand new and I think it included a new sensor obviously that's no guarantee that the sensor is working, though.

I am not using a machine to install the Freon I was just using a can hooked up to manifold gauges.

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Tuesday, April 28th, 2020 AT 7:43 AM

ASEMASTER6371

MECHANIC
52,796 POSTS

Yes, it is. Verify 5 volt reference voltage to the sensor. It sends a signal from the sensor to the ECM and that signal is converted into a pressure reading for turning on the compressor.

Roy

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Tuesday, April 28th, 2020 AT 7:47 AM

KTHEBUM