2011 Fiesta AC issues

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Hey guys- I'm working on the Fiesta that is blowing warm air.

I had it for another concern a little while ago and while on the test drive, I noticed that the cold air would come and go- typically with acceleration, kinda like the WOT cut out. Any way, customer didn't mention it as a concern, so I left it alone. A few weeks later she calls me saying that it's not working and that they added some refrigerant. So the first thing I did was vac it down and recharge with the correct amount- seemed to work ok. Well, she called me again stating that it went back to not working again. With the gauges on it, not running I saw 375psi on the LOW side and I think 75 on the high side. Running at idle, I'm seeing around 400psi on the high side and around 35 psi low. Raising the engine speed brings the high side down to around 300 or a bit more and the low up to 75-80 psi. All values are inside a climate controlled shop at 71*F and low humidity.

Any ideas? Stuck/sticking expansion valve?
 
No way can you have 375 on the low side. The evaporator would have exploded long before that pressure. Sounds like the hoses are swapped on your gauges or machine and the cooling fan is busted.
 
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Originally Posted By: The_Eric
With the gauges on it, not running I saw 375psi on the LOW side and I think 75 on the high side.


If the system is off and stabilized the low and high pressures should be about the same, and should follow this chart (assuming R-134a):

Temp+Pressure+R134a1312314815.jpg
 
Ok so I had a derp moment... I glanced at the low side gauge and saw that it was swung all the way around past 120psi, then saw the 350 on the gauge and didn't make the connection. So it goes 0-120 psi in incremental graduations, then a black line with Retard on it then 350. I just saw that and missed the rest.

Still, the point remains- high pressure and no cooling.
 
Originally Posted By: Chris142
Is the cooling fan working?

That is a good place to check. I had one that I was repairing where the fans weren't operating, and the symptoms were similar. It produced so much pressure the relief valve kept actuating.
 
There was a thread on here recently about a super high mile 2011 Fiesta. One of the repairs was the radiator cooling fan.

Thread

Originally Posted By: FutureDoc
Many would be "trade it in before it blows up" types of repairs:
Its clutch packs were replaced twice, at 347,000 and 545,000 miles. (Actually, the second time,]it proved much quicker and no more expensive to go ahead and replace the entire transmission with a nearly new, Other repairs included the main computer, fuel pump (it was making noises, Mike didn’t wait for it to fail), throttle-body motor, starter, alternator, coolant-recovery tank, radiator cooling fan, HVAC blower motor, body-control module, and the A/C compressor (“it was getting a little noisy”). The horn also was replaced, with a four-note unit from a 1971 Cadillac.
Every year it got: 26 oil changes and tire rotations 2 sets of tires 1 set of struts and shocks. Timing belt and water pump (really every 9 months, Mike got the job down to four hours)


 
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Just a guess..

Wrong one, pressure control valve is what I was looking for but cant find an exploded view.
 
Last edited:
Originally Posted By: kschachn
Originally Posted By: Chris142
Is the cooling fan working?

That is a good place to check. I had one that I was repairing where the fans weren't operating, and the symptoms were similar. It produced so much pressure the relief valve kept actuating.


Yes.
 
Assuming the blend doors are working it can only be the compressor or expansion valve. Quote 'em both.
 
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