bigirishlt1

iTrader: (9)

where is the Compressor Mounted High Cut-Out Pressure Switch part number 20055 located. it says compressor mounted but i cant find it. i got the other switch swapped now i need to change this one out so we can recharge the system.

Stepside

On my '07V; There is a high pressure switch about 5 inches behind where the low pressure fill port is.

The high pressure line runs, parallel to and underneath, the low pressure line on the left (drivers) side, -- ?,not near the compressor . . hmmm, maybe different for yours.

bigirishlt1

iTrader: (9)

Looks like this one? http://www.amazon.com/gp/product/B000C9C7AU

I got that one replaced still didn't fix the problem. Here is the other one that I have and can't figure out where the hell it goes.

http://www.oreillyauto.com/site/c/de...2012&ppt=C0053

The compressor just will not cut on. "service ac system" comes up on the nav screen. I used a little handheld code reader to reset the computer after we put the new sensor in, vacuumed the system out and put new freon in. And still the same thing it will blow for a second and then the service ac comes back up.

DMM

Think that is the only high pressure sensor in the AC system. What is the DTC and what are the pressures?

Stepside

Are you hooked up to the low pressure side starting the charge?
The old systems required that you bypass the low pressure switch in order to get the compressor running.
The newer system do not work that way. You just hook up to the low pressure side with the refrigerant and the compressor 'kicks-on' and it takes the charge when controls are set to defrost & max cool. Nothing to bypass.

X715453

Pretty sure you can by-pass the switch, if not probally try getting as much in as possible, through the high side, with the engine OFF, and placing the can in some warm, not hot water.

DMM

It is not a simple on/off switch, it is a sensor. Not so easy to bypass.

bigirishlt1

iTrader: (9)

The code reader I have is just a piece of junk walmart one. It will not read any codes unless it sets off the check engine light no abs codes or anything like that. I was going to take it to a shop and have them hook it up to their diagnostics machine if i cant figure it out soon. The static pressure is around 80 psi

Stepside

80 psi on the high side?
Should be a minimum of 91 psi.
Low side should be 21 - 32 psi

kevm14

Well since the system isn't running, 91psi at the high side is 91psi at the low side, which is pretty normal. Sounds like it's charged up.

bigirishlt1

iTrader: (9)

Just changed out the compressor and I'm still getting the service ac system on the screen!! What else is there to do? I'm fixing to give up and take it to the dealership.

LS2duc

iTrader: (1)

went through same BS as you for almost a month. Broke down and went to GMC dealer near me. They found a frayed wire, looked like it had rubbed againsts a Maggie pulley possibly? way in the back and almost at the bottom of the firewall. $1.87 part, $450 for labor!. Im going back there today my 2006 with 5K miles power seat will recline, wont move forward unless you push it whith your hands. Motor under seat sounds way F'd up. Service manager said "ive never seen this failure in 30 years of working on caddys!" Wish me luck... and good luck to you also. Sometimes you just gotta break down and go to the dealer. My "speed shop" gets $105 hour, GMC dealer $82, and a whole lot more experience with this type of problem. Took a 300 mile trip saturday 85 degrees out-theres NOTHING like a CTS-V top of the line A/C unit working up to speed. Had to keep turining the damn thing OFF it go so cold!

RADEoN

iTrader: (12)

did you clear the codes by chance? I'm fairly sure the A/C code won't go away until it's cleared.

Also, I had a broken wire from my high pressure switch. Traced it down to the back of right where it connects into the other harness. I just dug into the black wire mold, cut the wire, and soldered some new wire the whole way back to the sensor, and has worked like a charm ever since.

bigirishlt1

iTrader: (9)

RADEoN i should have listened to you and taken a better look at the wires i looked at the harness but didn't look too closely at the sensor it self. thats where mine was busted. the cadi dealership charged me 70.16 for about a 40 dollar part, 220 dollars in labor and i don't know how they managed to use 10.64 in shop supplies. they wanted to charge me another 110 to fill it up with freon. told them hell no, pulled the can out of the trunk filled it up and drove off with the air blowing nice and cold. it feels so nice to have it working. i love the way the black interior looks but damn was it hot without any ac. I should have just taken it to the dealer in the first place. instead of replacing everything, at least i have a spare compressor now. thanx for all the help guys.