Focus Mk3, 2015, 120ps, Diesel, (AC not working), AC compressor won't engage

[pfeilmayer]

Hello

Patient: Ford Focus Mk3, 2015, 120ps, 1.5 diesel
Symptoms: AC does not work (does blow cooled air), compressor and fan do NOT turn on.

What I've done so far:
1. Diagnosis. I have NO error codes on the car, none whatsoever.
1a. I also read the information in real-time, the video with the data will be posted in a link below.
2. I checked ALL the fuses in the 3 fuse panels: under the hood, in the passenger compartment, and in the trunk. I have NO faulty fuses!
3. I checked the pressure in the installation, and the pressure is correct, KOEO with AC off, and the pressure is identical on the HI and LOW sides (18 deg. C, +-30 PSI).
4. I replaced the pressure sensor (the fastest part to change so I have no other doubts regarding the sensor). Conclusion: the old pressure sensor is either good or the new one is defective. Probably both are good
5. I optically checked the 2-pin plug that goes into the climate compressor and the harness and I did not find any broken cable, eaten, cut, etc., under the car!
6. I measured if the compressor receives voltage. Here I discovered the first bug: NO, the compressor, on that 2-pin plug, does NOT receive voltage, although according to the button pressed and confirmed by the diagnosis, the command to start the AC exists!
7. To rule out the compressor/electromagnet, I fed the compressor directly, with other wires, from the car battery, and immediately the electromagnet/clutch engaged and started spinning.
- Problem 1 for point 7: The fan still does not turn on
- Problem 2 for point 7: although the clutch/electromagnet/compressor is powered directly, the car does not cool down, only normal air enters...
- Problem 3 for point 7: Even though the compressor is powered, the pressure on the HI and LOW remains relatively the same. Theoretically, once the climate is on (the compressor is running) the pressure on the LOW should drop to 0 and the HI should rise. NO, they remain the same

Other info :
8. With Forscan and Launch, the reading at "x1000 CACRP" is 399.0, with slight oscillations up to 401.0 (expressed in kPa). Ist the same when I have the engine off (Key On Engine Off) or with the engine running and if I'm not mistaken even when the engine is on and the AC is "on". („on“ meaning that it is set to a minimum temperature, set on auto or manual with maximum speed and the AC button pressed ...
9. The Pressure Sensor voltage is about 0.82V - 0.88V as shown in Launch and Forscan

What I haven't been able to test yet: relays. I'm going to get a relay tester and check those too.

I have no ideas left. I ask if anyone knows something, can give me an idea or if anyone has some experience, please give me some advice. To shorten the list of tips: NO, I won't go to the service, I won't go to the dealership, I prefer to remove all the AC from the car than to go to the service! 😄

Thanks in advance to everyone who takes the time and actively and positively contributes with any idea to solve the problem!

Info, pictures, and videos can be found in the attachment and in the links below:

Diag Data Stream https://www.youtube.com/shorts/obK4-gSmNP4
Diag Data Stream 2

Refrigerant Pressure

(important to mention: here I was powering the compressor/clutch externally with 2 wires directly from the car battery)


Additional info but I don't think it's very relevant: 2 years ago my climate radiator was changed under warranty. Somewhere it had a hole where the coolant was lost. As can be seen from the pressure test, I did not lose any pressure and it does not seem to be a problem.

 

[Handy Andy]

There are two things here...

Relays being checked - are you able to understand their "pinout" diagram.

Referring to the set of contacts that the relay closes - dead shorts - to turn on the FAN?





The only reason this is coming up, is to check the WIRING to the RELAYS - make sure the Fuses in that old bird work and are still viable - not as a simple colored jumper with numbers like 5, 10, 15 or even 25 - but as a working part of a circuit.

So, if a simple jumper across terminals 3 and 5 as shown above (yours may vary and understandably may have extra contacts that allow to BYPASS or function to power a device in the RELAXED state that shuts off when the relay clicks to the new set of contacts to engage and send power elsewhere. (Starter solenoid - for example - of this condition) ) Done with the engine running and to keep it simple - the climate control is also engaged to show AC - which brings up another point does the AC light on the switch even work? IF not - there are issues that go even deeper - it's the Tell-Tale that spells doom, then, there is something truly wrong with it.

Per above - Shorting 3 to 5 - should bring up the fan - if that doesn't - then further investigation and even ohmic checks for the wires to POWER the fan need Battery and Ground - the RELAY? Only needs Power from the HARNESS (12V) (low current demand) but needs the PCM or BCM to sink the power from the coil to operate. So if you verify the FAN works - the Relay or it's "trigger" wiring is suspect - this includes the PCM and or any place that shares and sinks current to engage the relay for that higher current fan.

There is also a DROPPING resistor (5.6Ω or so) to drop the voltage to slow down the rather noisy at high speed, fan so you can keep the engine cooler from the loading imposed on it from the AC system. This engages when the system is at normal temperatures and the outside air temp is also near comfort levels (above 50F) so the engine does not overheat and the COOLANT radiator is not sending heat to the condenser (outside heat exchanger) making it less effective.

Then you need to verify that even though the clutch is working - does the compressor even work?

Your gauges say otherwise - this may mean the compressor diaphragm that pumps this thru itself is shot - so it just vibrates the fluid in it - goes nowhere...

Lots of times the refrigerant has left the stadium and all that is left is the compressor oil used to lubricate it and provide sealing - only now that is all that is left.

 

[Handy Andy]

Further analysis - looks like you BARELY have enough pressure - it may not be enough to turn the unit on.



You might need to jumper the switch to see if you can "engage" the pump - but as I see it - it is engaged, just no VOC (the refrigerant) its not forcing a cooling - there is nothing there - verified by the HOT side only having a 2kPa increase

If I'm reading your scales right.

 

[pfeilmayer]

Further analysis - looks like you BARELY have enough pressure - it may not be enough to turn the unit on.

View attachment 6538

You might need to jumper the switch to see if you can "engage" the pump - but as I see it - it is engaged, just no VOC (the refrigerant) its not forcing a cooling - there is nothing there - verified by the HOT side only having a 2kPa increase

If I'm reading your scales right.

Hi Andy
Thank you for your input. I have checked the relays and they are ok. Regarding the pressure, I also have my doubts because if I read the pressure on the Gauge, on the PSI scale ... I have enough pressure (ca. 30 PSI) (I need between 25 and 35 PSI). But if I read the pressure with the diagnostic units (Launch and ForScan) I have about 399 kPa. And someone told me I should have 1400 kPa .... So I returned the Gauges and ordered new ones, somewhat more expensive, and after I receive them I'll red the pressure again ...
Have a great one !

 

[pfeilmayer]

Hi Andy,

Everything I did on the weekend is in the video below.
Please take a look: measuring pins from the relay, bypassing the relay with a jumper cable to power the compressor on, topping up the refrigerant, and replacing the sensor...

What I've done in the past few days:

 

[Handy Andy]

Ok, looking back to the Fiesta Thread, we had investigated the PRESSURE switch, located in the front, (you are facing the motor - in a '17 - the switch is located just below the and to the right of the Right side headlamp.)

Ford 6F9Z-19D594-AA
Switch - Air Condit.System - Vacuum



Are you able to locate your vehicles AC pressure switch?

This sensor - it's wiring snakes back thru the Right Headlamp harness - but if the wiring to it is bad, no AC no matter what...it's the cutoff switch. So you can try adding more FREON, but to me, you'll need to locate this pressure switch and do some voltage and continuity checks - the cutout switch if pressure is too low, you get nothing, too high? IT can damage the system. So I'd locate this switch and see if the CONTACTS work - as it this switch is a tri state one, so one terminal needs ground the other goes to the senders voltage source (PCM) and the third goes, returns to the PCM but shows "state" of Freon inside the unit.

So, verify voltage and one wire should show ground - you've got this far Good Job! Let's just hope is a bad wiring problem and just needs a little TLC.

​

 

[pfeilmayer]

Hi Andy
That pressure switch was replaced at step 4 (my first post). I may just named it pressure sensor.

"4. I replaced the pressure sensor (the fastest part to change so I have no other doubts regarding the sensor). Conclusion: the old pressure sensor is either good or the new one is defective. Probably both are good"

So, the pressure switch is ok. Both - new and old one

MEAT & DORIA: pressure switch, air conditioning
Article number: K52097
EAN number(s): 8033208222105

OEM reference number(s) comparable to original spare part number:

OEN 5044586 — FORD
OEN 5471192 — FORD
OEN BT4319D594AA — FORD
OEN HG1A19D594AA — FORD
OEN HG1Z19D594AA — FORD

 

[Handy Andy]

But are there any voltages to the switches?

Reasoning, they are one of the most exposed areas of the front bumper and trim.

You find the AC signal does exist, so then to me the wiring is more suspect

Another would be the expansion valve - that is located in the line that routes behind the coolant reservoir.

​

Wonder if that is broken.

Why? Little to none pressure gradient - that needled valve if its "dissolved" from oil and lack of freon - or broken - that line - its assembly - has to be investigated for finding it if it's still existing.