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

pfeilmayer

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Ford Focus MK3, 2015,1.5 TDCI,120ps
#1
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.
 

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Handy Andy

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#2
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?

1654736387086.png
1654773541769.png


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.
 
Last edited:

Handy Andy

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#3
Further analysis - looks like you BARELY have enough pressure - it may not be enough to turn the unit on.

1654826776766.png

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.
 
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Ford Focus MK3, 2015,1.5 TDCI,120ps
Thread Starter #4
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 !
 

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