A/C system advice (compressor doesn't spin up)

Automotive
#1

So my 2010 focus stopped blowing cold at the end of May and after some home diagnosis I found there’s freon in the system so a leak is very unlikely, but the compressor isn’t spinning up. A friend suggested I replace the a/c pressure switch just as a cheap check to see if it was bad, but I found out some Fords have a special valve there to close the system once you pull out the pressure switch and others don’t, and I don’t know if mine has it.
I want to just take it to a shop, but the ones around me seem a but shadier after new management, and one a friend recommended is a half hour from me. So I’d like a bit of advice as to how y’all would proceed.

Thanks in advance

#2

If the compressor has a clutch, the clutch coil could have burned out. That happened to our Honda. Thankfully it was replaceable without cracking the system open.

To diagnose, use a multimeter to check for voltage at the coil wiring connector. If there is voltage, check continuity on the coil itself. It should show something other than an open circuit.

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#3

How do you know how much freon is in the system? Is the pressure appropriate for that refrigerant liquid at that temperature? Even if it is, you still don’t know if you have a full charge, or just an ounce or two left.

Once there is no more liquid in an automotive system, you can still have pressure, just not enough to turn on the evaporator pressure switch. And most of the time, when people are taking on cooling problems, even with a leak, the system has not gone down to zero pressure. Fast leaks are generally rare.

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#4

Thank you both for the advice, I happened to talk to my neighbor this morning who recommended their shop of choice, so thankfully I have some piece of mind handing it off, now to just wait and see

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#5

Just as a point of reference, when our Honda clutch coil went out I bought a replacement on Amazon for less than $50. It wasn’t this exact one but was similar. I’m sure it’s available for many cars.

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#6

I am not a fird focus guy, but you might want to investigate weather of not the electric fan for the ac condenser is working. If not the ac will not work.

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#7

Mechanic did a basic ac service of capturing what was in the system, pulling a vacuum, holding it to check for leaks, and then filling to spec. After that it worked fine, so he told me he also added a uv dye and to come back if it acts up again. He said under or overfilling, as well as those stop leak cans can mess things up, I told him I had used such a can, but that was years ago when the o rings failed and it’s been serviced since with some key components like the condenser or evaporator (struggling to recall) replaced since

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#8

No explanation of why the compressor didn’t “spin up”? Low Freon won’t keep your compressor from spinning.

#9

Yes, it will on most fords. Instead of an expansion valve, they have an accumulator pressure switch that turns off the compressor before the evaporator pressure gets low enough to freeze up. So once the system runs out of liquid, it doesn’t take too much loss before the switch does not see enough pressure to turn on the clutch.

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#10

Low freon (low pressure switch) as Kbraby said or an over pressure switch will also kill the signal to the compressor clutch - protects the compressor & no one wants to throw the only belt driving the engine accessories due to an air conditioning problem. Depends on the system.
The bucket of shyte Honduh Element I have had a an ac clutch engagement problem the other day - but was due to the condenser fan pulling too many amps and killing the signal to the clutch.

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