2016 Limited AC Compressor Won't Engage Except When Jumped

[CDW6212R]

Oh boy, who has a picture of the engine bay to show where they are?

The AC lines have the pressure switches in them. Without a picture or diagram, the compressor is usually the place to trace the lines from. On each line if you follow it will be a small device with an electrical connector going to it, two wires. The lines go into the firewall of AC box outside of it, or the drier back there, the evaporator(or two) are inside the dash etc. The AC signal/trigger wire is going from the dash AC controls, through the firewall, to each pressure switch, and finally to the compressor relay which you have been working at. Somehow that signal isn't reaching the relay, or the AC control isn't producing the proper signal.

Someone with experience with the AC on the 5th gen's might chime in soon, with details about where the components are. A shop manual has everything of course, but people hunt on forums to solve problems they don't want to pay big money for a manual, or go to the dealer either.

 

[runningonfords]

Oh boy, who has a picture of the engine bay to show where they are?

The AC lines have the pressure switches in them. Without a picture or diagram, the compressor is usually the place to trace the lines from. On each line if you follow it will be a small device with an electrical connector going to it, two wires. The lines go into the firewall of AC box outside of it, or the drier back there, the evaporator(or two) are inside the dash etc. The AC signal/trigger wire is going from the dash AC controls, through the firewall, to each pressure switch, and finally to the compressor relay which you have been working at. Somehow that signal isn't reaching the relay, or the AC control isn't producing the proper signal.

Someone with experience with the AC on the 5th gen's might chime in soon, with details about where the components are. A shop manual has everything of course, but people hunt on forums to solve problems they don't want to pay big money for a manual, or go to the dealer either.

There's a switch I think on top of the condenser on the passenger side, the only"thing" with wires on it over there on the ac line. Is the low pressure switch integrated into the compressor? I will look later on in my knock off service manual for you.

 

[CDW6212R]

The LPS is usually near to the drier, on the line going to the compressor. The HPS is often close to the compressor, on the other line, to the condenser.

Look below, this is what the high pressure switch looks like on the 97-01 SOHC 4.0 V6's. I don't have any good pictures to show any other engines, this is from my 99 truck. This HPS is behind the compressor in the bottom right of the larger picture. You can barely see the back of it, and the two wires going to it. This just shows you what the LPS and HPS ought to look like, the size and shape.

 

[Swifty Morgan]

I really appreciate all the help. Do I need a $180 Helm manual, or will a cheaper manual get the job done?

 

[CDW6212R]

If you are keeping the vehicle for a while, buying a manual is a good idea. You can buy the cheaper brand type at parts stores easily, faster than the more in depth OEM or DVD copies of them. I've liked the DVD's better for use on a computer, but they aren't always easy to search through(some may be, I've only owned two brands/types).

I'd look online first to see if search words can find you what you are after, like the "AC low pressure switch Explorer 2016." Searching online can find most things, but the vast results that are unrelated are aggravating.

 

[runningonfords]

There's only one pressure transducer on these systems. Its where I said it was before, on the top of the condenser, passenger side, number 8 in the picture below.

 

[Swifty Morgan]

Okay. Thanks. I tried to bypass or activate that, but I didn't get anywhere. Now that I know for sure that it's a pressure switch, I'll try again.

It has three wires. No idea what they do or what the voltages are supposed to be. Maybe I can find an explanation online.

 

[CDW6212R]

Check with an ohmmeter from the AC clutch power wire to those wires, one should read zero when the switch is "open." Tracing that circuit back to the dash AC control should find the fault or break in the circuit.

 

[runningonfords]

I'm confused, how have you ruled out that the pressure transducer switch isn't the bad item here? I don't understand how you've arrived at a wire fault as the definitive problem. Not being condescending, I just don't follow and want to understand. I'd go buy a pressure transducer and swap it in (you can do this without evacuating the system) and see if it works ($25 online). If it doesn't, send it back for a refund.

 

[Swifty Morgan]

I'm confused, how have you ruled out that the pressure transducer switch isn't the bad item here? I don't understand how you've arrived at a wire fault as the definitive problem. Not being condescending, I just don't follow and want to understand. I'd go buy a pressure transducer and swap it in (you can do this without evacuating the system) and see if it works ($25 online). If it doesn't, send it back for a refund.

I haven't ruled it out. I'm trying to test for it. Thanks for the info on replacing the pressure sensor. I was afraid it would release the gas.

 

[runningonfords]

I haven't ruled it out. I'm trying to test for it. Thanks for the info on replacing the pressure sensor. I was afraid it would release the gas.

Don't take my advice about removal/replacement as gospel truth. It says as much in my book, but I'm not responsible if you don't check for yourself about the schrader valve on the pressure switch on the 2016. That **** is under high pressure and can absolutely blind or kill you!!! You're on your own, beware!

 

[Swifty Morgan]

Okay, thanks for the encouragement. I assume I will get some indication when I start to loosen it.

 

[Swifty Morgan]

The high pressure switch is fine. I bypassed the relay. With the switch installed, the AC works. Remove it, and the clutch stops.

I checked the voltage across the relay solenoid sockets. It's 2.5 V, regardless of whether the AC is on or not.

So here is a list of things that are okay:

1. Refrigerant level
2. Clutch
3. Pressure switch
4. Relay
5. Fuse

No "on" signal is going to the relay, so what's the cause?

 

[runningonfords]

The high pressure switch is fine. I bypassed the relay. With the switch installed, the AC works. Remove it, and the clutch stops.

I checked the voltage across the relay solenoid sockets. It's 2.5 V, regardless of whether the AC is on or not.

So here is a list of things that are okay:

1. Refrigerant level
2. Clutch
3. Pressure switch
4. Relay
5. Fuse

No "on" signal is going to the relay, so what's the cause?

What is the temperature outside?

Is it supposed to be 2.5 V? I thought I seen a video of ford ac relay stuff when doing mine and 5.0 V was mentioned about the relay?

I can look at the wiring diagram when I get home later. Also, the $15 eBay service manual is all I have and it's actually for 2012 model year but works fine for my 2014. It looks like there's one on eBay for 2016 for $25 instant download. Have to use acrobat reader to read it with clickable links.

 

[Swifty Morgan]

I don't know what the voltage should be, but it's 2.5 regardless of whether the AC is on, so the required voltage has to be higher than 2.5.

The only bookstore here has no manuals! Amazing. I may just pop for a Helm manual.

 

[runningonfords]

I don't know what the voltage should be, but it's 2.5 regardless of whether the AC is on, so the required voltage has to be higher than 2.5.

The only bookstore here has no manuals! Amazing. I may just pop for a Helm manual.

I'd go out on the limb of speculation a little further and say that the evaporator temperature sensor could be malfunctioning. The compressor I think won't turn on when the evap is at 32 to prevent ice on the evap. It's why I asked what the outside temperature is where your located. If that sensor is toast, it could be causing your problem. Is also behind the dash, might be a real ******* to replace.

What temperature is it outside where you're at?

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[Swifty Morgan]

It has been hot here; 90 at most.

I am going to check the cabin air sensor. The evaporator temperature sensor (thanks, Ford) can no longer be replaced as a single part. It's a $750+ job.

 

[runningonfords]

It has been hot here; 90 at most.

I am going to check the cabin air sensor. The evaporator temperature sensor (thanks, Ford) can no longer be replaced as a single part. It's a $750+ job.

Yeah I thought it's integrated to the giant evaporator, orifice, sensor mess under the dash. I've seen the YouTube video where they do that job, everything in the front dash and center console has to come out. Sorry if that's what's wrong, that sucks. Some YouTube videos about bypassing the evap sensor on a Lincoln zephyr seem like you might want to look at them. Worked for him.

If the dash temp display is showing 90F degrees then the ambient sensor is probably fine.

 

[Swifty Morgan]

I didn't check the ambient air sensor, since it was giving reasonable readings. I checked the cabin air sensor. All I was able to learn was that it had a resistance of 26K ohms, and it decreased when warmed. I have no idea what the resistance should be.

I have seen the bypass video. The question is this: what costs more? Replacing the evaporator mess, or bypassing the sensor and causing whatever damage may result?

 

[runningonfords]

I didn't check the ambient air sensor, since it was giving reasonable readings. I checked the cabin air sensor. All I was able to learn was that it had a resistance of 26K ohms, and it decreased when warmed. I have no idea what the resistance should be.

I have seen the bypass video. The question is this: what costs more? Replacing the evaporator mess, or bypassing the sensor and causing whatever damage may result?

Glad you understand what the bypass would do and the potential "cost". Pricey compressor. You could do it quick and see if it fixes your problem. Then actually fix it when you have time/money. Not sure if the prongs on the harness are the same as the video.

If you leave it bypassed then the system won't know the actual evap temp and won't cycle the compressor off when it's actually cold as all hell. This could really get freeze up quick, but depends on other things like how hot the air is, etc. Tough to say, I've never had a frozen evaporator.