I did some research and with some people's help, I think my AC pressure sensor/pressure switch doesn't work properly. When I try to turn on AC I see the light come on but it doesn't give me cold air. I checked and saw that the clutch doesn't get engaged. I recently did ac recharge and when I bypass AC compressor AC works perfectly. I left it on for like 15 min and it was giving me ice cold air. So we know air compressor works just fine. I also checked the relay and put it different fuse it didn't change anything.

I think I will just replace the AC pressure sensor on 2007 Buick LaCrosse. Before that do I need to do anything else? Simply unscrew and screw the one and give it a try?

  • Since i see an internally controlled (mechanical control valve, the little colored dot under the compressor's head) Delphi CVC compressor when i Google for the compressor of that model year, rest assured that you have the correct refrigerant charge if you're getting ice cold air. Also, the clutch would stop engaging only if the static pressure (the pressure in the system with the compressor clutch off) got below a very very low value (usually around 40 psi).
    – Al_
    Apr 18, 2019 at 21:29
  • I took the shop to evaluate and recharge AC two days ago.
    – Sami
    Apr 18, 2019 at 21:34

2 Answers 2


You need to be totally sure the pressure switch/sensor port has a Schrader valve. You don't want to vent refrigerant into the atmosphere and also accidentally vent it where you don't want it to vent (it gets incredibly cold when it evaporates, believe me; also, the PAG oil that would spray together with the refrigerant is nasty stuff).

I highly recommend you let a professional equipped with a refrigerant recovery machine handle all of this.

Anyway it's always good policy to disconnect the battery everytime you tinker with electrical stuff (fuses, relays, sensors, et cetera). But, again, the real problem is the refrigerant.

  • Thank you so much Al_. I really appreciate your time. I will take the shop again next week.
    – Sami
    Apr 18, 2019 at 21:35
  • Does Air Conditioning Schrader Valve need to be replaced as well?
    – Sami
    Apr 18, 2019 at 21:47
  • @Sami They tend to develop leaks, so it's a good policy to replace them whenever you get the chance. Provided the pressure sensor port has one, however.
    – Al_
    Apr 18, 2019 at 23:32
  • So I replaced the ac pressure switch but my problem still exists, any other ideas?
    – Sami
    Apr 23, 2019 at 1:45
  • @Sami Oh well, it has to be an electrical problem then. I think you have to check the harness.
    – Al_
    Apr 23, 2019 at 22:07

Thank you everyone, the problem has solved. It was the low ac pressure switch, not high-pressure switch

  • What compressor do you have out of curiosity? If you have two switches instead of a single transducer then it's unlikely it's the variable displacement compressor i thought you had...
    – Al_
    Apr 29, 2019 at 22:59
  • 1
    I dropped my car the shop and he called me saying that the problem was ac pressure switch and I told him I already replaced that part then he said it should be another pressure switch and they will change and ac will work just fine. I went to pick up my car and they told there is only one pressure switch and the problem is something else. I posted here before I picked up my car.
    – Sami
    May 2, 2019 at 17:17
  • 1
    He also said it is a wiring issue in the fuse block. Tested power to the ac solenoid and fuse, but no power in between. They couldn't fix it so I will take the car to the dealer. I hope it is not crazy expensive to fix.
    – Sami
    May 2, 2019 at 17:19
  • Sounds like i was right in my belief that you had the variable displacement pump. Oh well, good luck. Wiring issues can potentially be a pain in you know where.
    – Al_
    May 4, 2019 at 11:25
  • Yep, you were right! Since the local shop said he can't do it I took my car to the dealership and, they told me I have to replace the fuse box for 800 dollars :) She was like the part is 500 dollars. I will go to pick and pull and get the fusebox for 15 dollars and replace it bymyself.
    – Sami
    May 4, 2019 at 17:42

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