tbran
Guest
one is lOW pressure, the other is HIGH pressure. If the pressure gets too low or high the circuit is broke and the compressor is declutched. Ususally 20-35 lbs breaks the low _ 375n usually pops the high switch. BTY we have found a BUNCH of systems on all makes converted to 134a. It is easy to overcharge 134a. One doesn't clear up the bubbles in a sight glass as in R12. A rule of thumb is at mid throttle the low side should be less than 20n and high should max at 150n plus the outside temp. (90 degree day = 240n) To check out the thermostat turn the fan to lOW speed, close the door and set to MAX recirculation of air and watch the low pressure. lP should come down to 5-6 lbs before the thermostat kicks out the compressor.