Question about 2002 Ford F250 Super Duty SuperCab

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A/C compressor clutch won't engage, system won't cool

Checked voltage to clutch but has none (meaning the controller is not sending the signal ok), the cycling pressure switch on the low side is open with the engine off, and open with the engine running, I removed it and still checks open, not sure if it its the normally open type or normally closed type. If I jump short the terminals to the low pressure switch, then the compressor clutch engages........... The high pressure limit switch on the high side (on top of the compressor is closed with engine off and closed with engine on and AC running. Blower motor runs fine in all settings, but blows hot air only. makes little temperature difference when set to AC setting. QUestion is...... Is the low pressure switch the normally colsed type? and .......what's the normal reading on the high pressure side of the line? I have an A/C manifold set to check both pressures. thanks for any inputs.

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  • borntobelong May 25, 2009

    I recharged the system and the compressor began running (now the clutch engages), before that, I verified the cycling switch by removing it and using compressed air to test it, and it does close at around 40 PSI, so it's ok. now that the system is recharged compressor runs, but the air in the cabin still comes out hot. even at AC max. I did fix a broken vacuum hose that goes to an actuator, which shuts off the outside air into the cabin when AC is set to max, but that did not help. I tried recharging the system to get it to the appropriate charge but even with the compressor on, it will not take in anymore gas (pressure still reads less than green area on my gauge). Can anyone get me some insider ideas as to how to make the system accept more gas up to the right pressure? thanks.


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Your system might be low on freon. Get a kit with a hose that has a gauge on it so you can see if you are in the "Good" range. The cycling switch won't close unless there is enough freon in the system. You can temorarily jumper the connector for the cycling switch to see if the compressor will come on. If it does, you are low on freon for sure. Do not let the compressor run for more than 15 - 30 seconds with it jumpered.
report back results.

Posted on May 21, 2009

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Sounds to me like its simply ran out of gas!, get the system inspected, the clutch wont engage if there is no pressure in the system, hence the switch problem.
Get it recharged and check for leaks, vehicle with air con will loose around 50grams per year from normal usage, if its been years since it was check it could simply just need recharging.

Posted on May 21, 2009

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HVAC Compressor Controls Circuit Description
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