Ac compressor cycling - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 05-14-2014
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Ac compressor cycling

So now it's warmer, the AC is blowing cold, but the compressor is cycling on and off very frequently. Put a refill can in it, 10oz, and still the same. The gauge flucuates to ~45 off and 25 on. Do I just need to keep filling or something else going on?
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Old 05-14-2014
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The air gap on the AC clutch might be getting to big or the coil is getting too weak.

To test the coil you need an OHM meter, set it for 100 OHMs remove AC wires from coil/compressor, test compressor contacts, should be about 4 ohms.

When power is passed through this coil it becomes an electro-magnet this pulls in the metal Clutch plate and causes compressor to spin with the pulley.
The "air gap" is the space between coil and clutch plate, it should be 0.02-0.03 when it gets larger the coil can't hold the clutch plate very long, so you get cycling on and off.
Or if the coil gets weak the same thing happens.

Good video here on checking and fixing the air gap........and it is free


You can also check if the voltage on the coil wire is turning on and off, remove the connector again an start engine, turn on AC and check if voltage for the coil is steady, if it is switching on and off then you could have a bad pressure switch or..........

Last edited by RonD; 05-15-2014 at 02:31 PM.
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Old 05-15-2014
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Thanks, lots of good info/tips!

Compressor reads ~3.5ohms, gap is about .035-.040.

But if I run AC or Max AC AND Max fan, the compressor runs non-stop (at least 5-6min straight); it only seems to cycle quickly in the low fan setting, about 15 seconds on, 15 off, repeat. Normal?

It was reading about 37 and dropped to 30 psi during the long Max AC test and stayed at about 30.

When the compressor was disconnected or the truck off, psi went to ~90, is that normal? (Did I over fill?)

Bryan
99 3.0 155k
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Old 05-15-2014
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AC clutch reads OK

PSI on the low side will always go up with system OFF, ignore that.

Test low pressure with engine running and AC set on max, I would add a bit more, 35-40psi on long term test would be better.
Low side switch will cut out around 20psi
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Old 05-16-2014
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I had a problem with the AC cycling at idle. The shop said it was low on Freon. They charged it and the problem eventually came back. They checked it again and decided it was a defective AC clutch relay. That still did not totally resolve the problem.

I ordered a new pressure cycling switch and installed it. The AC is working great now. It also appears to have solved a problem of the AC icing up and stopping air flow after running for an hour or so on long trips.
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Old 05-25-2014
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Icon3

Mine 'clicks' on & off all the time.....I'm going to check the 'air gap' tomorrow!

Last edited by RandyinCCTX; 05-25-2014 at 12:15 AM.
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Old 05-28-2014
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My AC turns on and then blows cool not cold , but after a couple of minutes the air stops coming out. I can hear the fan running but the air just stops coming out of the vents and then it will start again but only for a minute or two. What do I need to check ?? PLEASE HELP...

Last edited by JimRickard; 05-28-2014 at 08:55 AM. Reason: clarification of question
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Old 05-28-2014
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Well the AC needs to be re-charged if it only blows cool not cold, but it could be the Blend door is not moving all the way so cold air is being mixed with warm making cool.

This Blend door issue could also be why the air stops blowing out the vents then starts again.

This is a video of changing the Blend Door actuator(motor), this motor is controlled by the Temp **** on the dash, this may or may not be the issue, the Blend Door itself may be loose, so not able to control air flow reliably.
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Old 05-28-2014
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Thank you for the info. I really appreciate the help.
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Old 05-28-2014
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In addition to what RonD stated above, when the air stops coming out the dash vents, put your hand over the defroster vent outlet on top of dash and see if the air is coming out of there.
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Old 05-29-2014
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No, I dont feel it at the dash vents but I hear it blowing, I almost want to say I feel it getting cold on the floor but it is not coming out those lower vents either. any suggestions?
Thanks
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Old 06-06-2014
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Yes, the air keeps blowing cold but moves from the dash vent to defroster. Do you know what it it causing this?
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Old 06-06-2014
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Google: ranger blend door fix

This is a common issue, there are a few videos on it and several fixes.
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Old 06-06-2014
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Air blowing to the defrost vents is the default. If you are getting no vacuum to the selector switch, you get air to the defrost vents. That is how later Rangers work anyway. I think yours should be the same.

Check the vacuum line going to the selector switch to make sure it has vacuum when the engine is running. If not, a vacuum line could be damaged or disconnected. Your vacuum reservoir could also be damaged or the check valve in not working. If you have vacuum to the switch, your selector switch may be damaged.
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Old 06-06-2014
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Thank you
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