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Mk4 Mondeo Air Conditioning Pressure Switch?


jeebowhite
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Hi guys,

So my air conditioning stopped working shortly after it was first regassed. I took it back today and the machine reported 3 and 40 as the readings. They topped it up a little and now the air con is coming out a little colder. He said it might be the pressure switch, but Google isn't returning any results for this.

Is it a switch or a sensor? And how easy is it to replace?

Sent from my MY SAGA C2 using Ford OC mobile app

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Anybody at all got any thoughts?

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Well, I phoned a garage, and they would want over £120 to diagnose the issue - I just dont have that money, so now is where the hard work begins. I guess I need to try and diagnose this myself, or find a way to get it checked out with minimal cost!

Does anyone have any tips on how to test the air con system (the self diagnostics shows no error codes!) so it looks like its a job for a man with a spanner!

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AC isnt really my thing but this is the little i know/ have heard -

As far as i am aware on the mk3 (and the mk4 is probably similar) there is a simple on/off switch pressure sensor if the pressure drops below a certain threshhold the AC does not come on at all

the pressure switch is in a "T" piece on the aluminium pipes - it has 2 wires coming out of it

I recon the switch is ok because if the pressure dropped below a working threshhold it would switch off the AC off completely and that is not happening

If the refrigerant has been renued and the system is holding its pressure then the chances are its the pump

Older models like the mk3 had a big, heavy-duty AC system that used a lot of engine power / reduced economy but when the AC was on and working properly it produced an icy blast down to low (fridge-like) temps

More recent models (ecoboost petrol, anyway) have smaller, lighter AC systems that only work down to 7 degrees C - this is for performance/ economy/ safety (eco)

I don't know about your car and how powerful the AC is supposed to be - perhaps other owners with the same model can help

If you need to get parts, other Ford models may use the same components

The temp control mixes the cold air with the hot air from the heater, so try turning the temp down (much) lower on the controls to cut the hot air to see if that works (eg put it at fully cold/ if you want 18 degrees set it at 7 or lowest)

The radiator fan comes on when the AC is switched on - if the radiator fan does not work, neither does the AC (i dont think this will be your problem, though)

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Thanks FOCA, the thing is, I do wonder if the switch or the wiring is the fault.

to recap, when he did a little "topup" on my last visit, I came out with a rather cool blast of air (not icy just nice and cold) the EATC was set to Lo (under 17 degrees) but after a couple of days again it stopped. if I set the fan to Lo on full power, I get a relatively warm air blast at me. Even after he topped up the gas and initiated the aircon, there was no reassuring thud of the compressor clutch engaging (perhaps refers to the issue? or perhaps its nice and quiet, I am unsure yet). Sadly, the Haynes manual makes no reference at all to this sensor, so I cant even locate it with the manuals help to take it out and do a resistance test).

The issue is without hundreds in my pocket to just diagnose it, I guess I need the best way of pinning down which part of the puzzle is the problem, but with no error codes to help, and no detailed information on the interweb, its almost like finding the missing piece of a completed puzzle, without being allowed to use any of your senses!

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How long is Aircon surpose to last as I've noticed mines needs refilling?

Sent from my HTC One X using Ford OC mobile app

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it can naturally disperse over the course of a year or two, ordinarily just enough so that it does work well, but of course over 2-4 years it can become unusable.

I have booked the car in, the guys who did the topup initially are going to do diagnostics for £30. Cheaper than most places I have found and if it is a leak I will be contesting with the seller to get that refunded along with the repair.

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I've had it 2 years and it's over 4 years now I'll speak to my son in law (mechanic) he owes me a big favor;-)

Sent from my HTC One X using Ford OC mobile app

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Lol I wish I knew mechanics who owe me lol

Sent from my MY SAGA C2 using Ford OC mobile app

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