Does anyone know what the correct behavior of the air conditioning system in a 2009 mk 7 fiesta should be?

Currently, doesn't cool as well as i'd expect it to after a full air-con service, the compressor clicks on and off every 30 seconds sending a large amount of revs through the engine, While it is doing this the pressure of the system changes as well, when it clicks off it drops down to 35 psi and then when it clicks on it jumps up to 45 psi and then gradually raises up to just above 55 psi, then clicks off and drops back to 35 psi. IT does this every 30 seconds. When the system is off the pressure is just below 55psi

Question is, is this normal behavior or should i be expecting to see something different?

How have you pressure tested it?

Doesn't sound Normal to me.. gradual changes maybe, but not that extreme/sudden

Whats the temperature difference between the ambient air temp in front of car and the outlet from vents in car at 2000rpm with fan on no3 speed air con on , recirc off ? Thats the first check to do .

How have you pressure tested it?

Doesn't sound Normal to me.. gradual changes maybe, but not that extreme/sudden

All ive done is put a pressure gauge onto the service port for the aircon, thats how i got the readings in my original post

Whats the temperature difference between the ambient air temp in front of car and the outlet from vents in car at 2000rpm with fan on no3 speed air con on , recirc off ? Thats the first check to do .

Only drops to about 15*c if the ambient temperature is 20*c and when the compressor switches off it raises back up

The problem with testing the car at revs like 2000rpm is that when the aircon is running its impossible to keep it at 2000rpm. When the compressor kicks in it forces the revs up to 2500rpm - 3000rpm and then itll click off and drop to 1500rpm andnthe gradually rise back to 2000rpm.

I see it as quite dangerous as it pulled me across a roundabout once when i let off the accelerator

Surely this behaviour isnt normal?

Got a couple of pictures, don't know if it'll help, Attached to this post. Theres a picture of the pressure when i checked it this morning before starting the engine. To take the temperature I'm using an Air-con temperature probe that you stick down one of the vents.

The picture called beforeTemp is the temperature measured this afternoon before running the aircon - the outside temperature of the car is around 22*c and the temperature inside according the the temperature probe is around 45*c.

I then set the Aircon running on fan speed 3, cool and without recirc and left it for a few mins, the temperature drops down to around 20*c and doesn't budge any lower (afterTemp picture), even after a 15-20min drive and it really doesnt make much of a difference to how warm it feels.

I also have a video of the pressure gauge going up and down if anyone wants to see that

How can you have 20c outside temp and 45c inside?? must be like unbearable !! Have you got manual temp control or electronic control? Even without air con on what temp you have outside should be roughly what comes out vents, all the fan does is blow it through

How can you have 20c outside temp and 45c inside?? must be like unbearable !! Have you got manual temp control or electronic control? Even without air con on what temp you have outside should be roughly what comes out vents, all the fan does is blow it through

First picture was when I'd just got In the car and started the engine so just had cool air on. It was so hot inside the car because the sun was shining on it, so it heats up inside as you'd expect until you put the fans in.

Either way though, the car doesn't cool as well as I'd expect. With this aircon issue it's actually cooler for me to drive with the windows open :-(

My question is for you guys, how does your air conditioning behave, and does the compressor cycle on and off? I miss counted in my original post, it actually happens every 10 secs.

That sounds better, so basically your not getting any cooling effet then if 20c outside and inside. If 20c outside you should be getting 8-10c out vents

Manual or electronic temp control?

Did you get a printout with aircon service saying how much refrigerant was removed and how much put back in,

Fiesta does cycle like you describe,

That sounds better, so basically your not getting any cooling effet then if 20c outside and inside. If 20c outside you should be getting 8-10c out vents

Manual or electronic temp control?

Did you get a printout with aircon service saying how much refrigerant was removed and how much put back in,

Sorry yes that sounds about right. And it is manual temperature control. Doesn't have climate control. The cycling on and off and pressure jumping up and down as well as it causing the engine revs to jump up massively only started after the service.

I didn't get a sheet, just an invoice. Had it checked at another garage and they told me the correct amount of coolant is in the system.

so asuming the correct amount of refridgerent is in system, that leaves the cooling fan or expansion valve. does the radiator cooling fan work? and does the expansion valve feel cold? thats next to bulkhead before going inside car.

so asuming the correct amount of refridgerent is in system, that leaves the cooling fan or expansion valve. does the radiator cooling fan work? and does the expansion valve feel cold? thats next to bulkhead before going inside car.

Radiator fan definitely works, sounds like a jet turbine, hard to miss Haha! And yeah the expansion valve goes really cold when the compressor kicks in but then when it turns off it warms slightly

can you access the pipes inside to feel for very cold pipe and warmish return pipe? cant think of anything else without seeing car and im too far from you.lol

can you access the pipes inside to feel for very cold pipe and warmish return pipe? cant think of anything else without seeing car and im too far from you.lol

Not too sure if i can to be honest, I only really know where the pipes are in the engine bay. I've got a video earlier of how the pressure changes when the car is idle and the aircon is running, see below. It does the same thing when the engine is revved up to 2000rpm but instead its between 35 and 55 rather than the 25 - 45 shown below -

https://youtu.be/ST8qgAtGgiM