# 69 A/C question



## dan woodland (Jul 24, 2013)

Hi all,

My A/C system (R12) all original except compressor and Heater activated vacuum valve is always on no matter what setting I have on the dash... Heat, cool, etc... this makes the system ice up... and stays iced up.

Question: is the A/C system compressor supposed to be on all the time no matter the selection on the dash? If not what is the issue and how do I fix it?

Thanks in advance, as always any help is appreciated.

Dan


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## tjs72goat (Jul 20, 2017)

I read in another post the new compressors run all the time and will ice up. There is another part that is added to the system to prevent that. Not sure what it is.


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## 1968gto421 (Mar 28, 2014)

Dan, most A/C compressors have an electric clutch on the front driven by the fan pulley and the clutch is activated when you turn on the A/C by dash controls.Could the new compressor be lacking the clutch or nor wired up? IMHO


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## Montreux (Mar 8, 2009)

No, the compressor should not be on all the time. It should only be on in A/C positions (two furtherest right positions?)

There is an open switch (contacts that look like ignition points on the end of metal arms an inch or two long) on the dash controller that sometimes sticks. Surf eBay to get a look. If you can’t get the factory switch to work, you can add an underdash switch to control the compressor. This will allow you to run the compressor on defrost to defogger the windshield like a modern car. 

Meanwhile, you can simply unplug the clutch wire at the compressor. 

Also, system should not be freezing up. Low side pressure is too low. Maybe just needs topping off, or there may be a restriction in the valve.


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## dan woodland (Jul 24, 2013)

Thanks Gents. I'll have to investigate further.

Yes, it has a clutch. I was thinking the same thing Montreux. I was in the dash quite a bit for the restore. The original unit worked correctly so it could also be the low pressure you mentioned.


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