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High pressure switch on R134a conversion...

mckpaul on Fri October 05, 2007 5:56 PM User is offlineView users profile

Year: 1984
Make: Chey
Model: C-10 Pickup
Engine Size: 305
Refrigerant Type: R134a

I know the high pressure switch is required on a R134a conversion, at least it is on mine since I don't have on in the system already. I noticed the "T" fitting kit that ackits sells says that the switch is for both low and high cut off.

Does this "T" fitting get installed on the high side service port? If so, is it safe to assume that this one switch on the high side does the job of the low pressure cutoff switch on the accumulator as well so I no longer need that one? Or should I leave the existing low pressure switch on the accumulator in the circuit as well?

Have no problem understanding or doing the wiring, but need to know if the new switch is an addition to the circuit, or basically a replacement for the old switch just in a new location.

Thanks - Paul

Chick on Fri October 05, 2007 7:41 PM User is offlineView users profile

it's a "one switch" fit all type of fitting, since it's used on CCOT systems as well as TXV system that don't have a cycling switch. But don't do away with the cycling switch, as it is different than low pressure cutout..Just wire it in and you'll be fine..The low pressure switch will shut the compressor when the system pressures are to low (like a leak) while the cycling switch serves another purpose...

Email: Chick


Freedoms just another word for nothing left to lose

mk378 on Mon October 08, 2007 9:42 AM User is offline

Cut one of the wires to your existing cycling switch and splice one of the wires from the new switch to each of the cut ends. Now the two switches are in series so when either one opens, the compressor will stop. You need both active.

Some GM R12 systems were equipped with a HPCO switch in the compressor. If there is an electrical device in the back of the compressor opposite the pulley end, that is a factory HPCO and you don't need to add one.

mckpaul on Mon October 08, 2007 12:19 PM User is offlineView users profile

Thanks for the input. My high pressure port is on the passenger side down low (that line is attached to the frame), and it's not all that far from the accumulator, so I can install the new switch here and easily route the wires to the existing low switch and series it in, and run both swithces.

My current old compressor doesn't have a switch on the back, I don't even think it has a plugged hole for a switch. However, I am going to be replacing the compressor, so if the new compressor has a plugged hole on the back for a switch, it would be nice to put a high pressure switch there instead of on the high pressure port on the line, since I could easily series it in to the comperssor clutch wiring right there. But since my truck didn't have a high pressure switch there to start with, would it be difficult to find a switch to go directly on the compressor? Guess it would need to be a "kit" type switch as well since I'd need the connector and pigtail. Are those available, or am I better off just going with the "T" fitting kit on the high pressure port?

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