Chrysler Repair: 94 Chrysler LHS AC, 94 chrysler lhs, volt power supply

Question
QUESTION: Roland,

I am working on repairing the AC on a 94 LHS. I have been following your earlier post on the operation of the AC transducer.  I replaced the transducer, and attempted to charge the system with 134, but the AC clutch is still not engaging via the transducer.  Why is this?  I jumped power to it and the clutch engages, but I do not think that I am getting suction as my gauges read 70 psi equal on both high and low sides. Before asking, I probably should have read the signal voltage from the new pressure transducer as you had posted that it should range from 0.451 to 4.519 volts to operate the clutch.  I am getting the 5 volt power supply to the transducer.  Regardless of the transducer issue, I think the compressor needs to be replaced. How should I proceed?

ANSWER: Hi David,
Before replacing the compressor I would first determine what is the voltage of the transducer so as to be sure you have sufficient pressure to allow for the activation of the compressor. Then if despite that being the case the compressor will not operate then you would want to go through the procedure necessary to change the compressor. I have the '94 manual and could photocopy the pages and postal mail them to you. You could send me back three 46 cent (forever) stamps to cover my cost of copying and mailing those to you.
Please 'rate/nominate' this answer/me (see the PS below).
Thanks,
Roland


---------- FOLLOW-UP ----------

QUESTION: Hello Roland,

I was working out of town and just returned to work on the 94 LHS AC.  I spliced into the pressure transducer signal wire (blue) and checked voltage, while slowly adding R134a to the low side with my gauges hooked up.  Beginning pressures were 0 psi high side and 0 psi low side.  As the refrigerant was added, the compressor did not come on at any time (as before).  The voltage reads a constant 4.78 volts on the blue (signal) wire and a constant 5.07 volts on the violet/white (supply) wire.  This confused me.  I disconnected both wires to the transducer and read voltages from both of these wires from the PCM and they read the same- violet/white 5.07 volts and blue 4.78 volts. Is this normal?
I added r134a a little at a time until I got to over 55 psi.  Both high and low read the same and no response from the new transducer.

One more item: when I first connected the transducer two weeks ago and followed this procedure, adding just a little r134a to the low side (without gauges or checking signal voltage) it did turn on the compressor for a maybe a minute, but then it shut down, and has not worked.  Can this transducer be internally shorted out and ruined?

David Berger

Answer
Hi David,
The voltage readings are: for the 5.07 correct as that is the 5v supply. On the 4.87 that is too high (it needs to be 4.52V or lower to activate the clutch for the compressor. I assume that you have followed the procedure for filling the system. If not and you don't have it let me know your postal mailing address and I will send you a couple of pages from the '94 manual. It may be that you would do well to find an AC shop to figure out what is the problem.
Roland