2011 mustang 3.7 a/c compressor not engaging

[Manny003]

I have a 2011 Ford Mustang 3.7 the ac doesn’t engage. I replaced the low pressure switch, relay, and control unit. Also charged the system and gauges reading on point. I checked the ground on the low pressure switch and I have good ground, but no power going to it. If I jump the relay the compressor does kick on. All fuses and relays are good. I’m not sure where to go from here. Is it possible the computer is damaged?

 

[Juice]

IIRC, there is no low pressure switch on 11-14s. So you must be talking about the high pressure switch on the compressor discharge line. Going from memory, the 3 wires are: 5v, signal ground, and signal return. So no power at that sensor might be the pcm.

 

[Manny003]

I charged the system with freon it’s not over or undercharged, replaced low pressure switch, a/c control, and relay (fuses are good). If I put the relay on and leave it up a bit and put ground to a pin the a/c compressor kicks on. I check power to the low pressure switch no power but I have ground. Not sure where to go from here. Possibly the computer?

 

[Juice]

I would scan for codes and check circuits involved for continuity before buying parts.

 

[Iceman62]

Or...the compressor simply sh@t the bed & needs to be replaced. Could pull one fm a salvage yard & see if that's the case.

 

[13v6]

Check out this video from Scotty

 

[86GT351]

Maybe this will help for electrical

 

[86GT351]

 

[86GT351]

 

[Juice]

Or...the compressor simply sh@t the bed & needs to be replaced. Could pull one fm a salvage yard & see if that's the case.

How? He bypasses/jumpers the compressor and it kicks on.

 

[Forty61]

I charged the system with freon it’s not over or undercharged, replaced low pressure switch, a/c control, and relay (fuses are good). If I put the relay on and leave it up a bit and put ground to a pin the a/c compressor kicks on. I check power to the low pressure switch no power but I have ground. Not sure where to go from here. Possibly the computer?

I haven’t bothered to look over the schematic on my phone but if you jump that relay do you then have power at the pressure switch? If the relay is what powers that switch then work back towards what kicks that relay on. If the switch is a required input to kick on the relay then work from the switch back and see where you’re losing your power.

 

[eighty6gt]

I like Scotty's idea! That guy is a maniac! Just leave it on until it blows up!

 

[07gts197]

What are your pressure readings? I’m guessing you are jumping the pressure switch to get the compressor to engage while taking the reading.


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[Iceman62]

How? He bypasses/jumpers the compressor and it kicks on.

Just a stab in the dark...we had similar situation w/ son's 1st car (Chevy Crapalier) and ended up pulling a compressor (u-pull-it) and it magically worked from there on. Don't know if it's something internal to the unit w/ Fords, but it would rule it out & then he'll have spare f/ next AC fail.