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Low side clutch cycling switch questions

rt707 on Thu August 20, 2009 8:42 PM User is offline

Year: 79
Make: Ford
Model: Ranchero
Engine Size: 351
Refrigerant Type: 134a
Country of Origin: United States

Hello everyone. I have a 79 Ranchero that i totally rebuilt the whole A/c system. New paralell flow condensor, rotory compressor, all new hoses, expansion valve and POA/STV eliminator. Works awesome as long as the compressor is engaged, low side switch cuts out at 22 PSI but doesnt cut back in until 43-44 PSI. By the time the compressor cuts back in the air coming out the vents is 45-50 degrees. Its very annoying to be driving around town having the vents go ice cold then cool and back again to ice cold. For now I adjusted my switch down to 15 PSi cut out but I know I will eventually run into evaporator freeze up. Funny thing is that it still cuts out at 43-44 PSI after I adjusted it lower. What I was wondering is, does anyone know of a switch with closer "on-off" pressures? Such as off at 22 on at 32 or something like that, I understand that with this type of switch the temps will vary a little but a smaller variance would be much nicer. I thought maybe a low pressure switch off of a newer vehicle that uses 134a like a General motors product in the 95 up range. What do you guys think? Thanks in advance for any and all help.

mk378 on Thu August 20, 2009 10:42 PM User is offline

Forget the POA eliminator. Ideally, use the valve like stock, they work with R-134a. If you can't procure a working POA valve, fit a temperature switch to the evaporator. Leave the "POA eliminator" in line but don't hook up the switch. Bottom line is don't try to cycle a TXV system on pressure.

rt707 on Fri August 21, 2009 3:04 AM User is offline

Thank you for your reply. I kinda figured that was the answer to my problem. If I were to use a temperature switch do I have to put it in the fins of the evap or can i attach to the outlet tube and insulate it? Also, where I can I buy a temperature switch? Thanks for your help.

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