Automotive Air Conditioning Information Forum (Archives)

vcsmike on Wed September 17, 2014 11:25 PM

Year: 1973
Make: Alfa Romeo
Model: Montreal
Engine Size: 2.6
Refrigerant Type: R12
Ambient Temp: 95
Pressure Low: 35
Country of Origin: United States

I am having a difficult time finding this part. It is a simple pressure switch that threads into the low side manifold on a Tecumseh compressor in my case, but I've also seen the same switch on York compressors of this era. The wire from the A/C temperature rheostat connects to one side of the switch, & the other side of the switch goes to the compressor's coil. It's 3/8 24 male threads.

I have a full charge of refrigerant, yet the switch has very high resistance. So the clutch will not engage consistently. The system performs fine if I bypass this switch, but I don't want to leave the system this way as the pressure switch is the only thing that will protect the compressor in the event of refrigerant loss, which is a very real possibility on such an old system.

Everything I've found that would thread in it's place is a binary switch intended for the high side. Any guidance as to a source for this switch would be greatly appreciated. I will post a photo of the switch tomorrow.

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Michael Keith
Vintage Car Solutions
Houston, TX

mk378 on Thu September 18, 2014 8:59 AM

Can you relocate the switch to the high side? A HPCO function is good to prevent loss of refrigerant from blown hoses.

Edited: Thu September 18, 2014 at 9:01 AM by mk378

vcsmike on Thu September 18, 2014 10:15 AM

Unfortunately not. This is a collector car, & originality is paramount.

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Michael Keith
Vintage Car Solutions
Houston, TX

vcsmike on Thu September 18, 2014 12:07 PM

Here is a photo of the switch in question. It is toward the upper right. It has two spade connectors, although only one can be seen in the photo. This particular compressor is a Tecumseh, but I have seen this same setup (pressure switch on the low side manifold) on a number of Yorks used on European cars in the early & mid 70's. In fact, I have a 73 Alfa GTV with a York compressor in the shop right now with this same pressure switch. It seems commonplace, & I'm surprised that I'm having such a hard time finding it. However, I upgrade most of these cars to rotary compressors, & as such, I'm usually not having to deal with this switch. However, because of the packaging of this particular car, that is not a possibility.



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Michael Keith
Vintage Car Solutions
Houston, TX

Edited: Fri September 19, 2014 at 1:59 PM by Automotive Air Conditioning Information Moderator

bohica2xo on Fri September 19, 2014 1:54 PM

3/8-24 low pressure switch:

3/8-24 low pressure switch from AMA

B

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"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.