I've been having a slow leak on the system on my 2005 prius and had to add freon (without additives, seal leak, etc. - I did read about wrong oil type and/or sealant killing compressor) every 6 months or so (3 times so far). Until now, it was a trouble free process. Few days ago when I went to use AC, I got warm air. Put gauges on and didn't see a problem with pressure, the problem is different - Air conditioning compressor doesn't turn on. I bought mini vci and got DTC B1476. I tried diagnostics and successfully ran cooling fan. My static ac pressure is 40psi. I checked pressure switch and it's good = closed, tried to jumper it - no change. I disconnected inverter from compressor and tried both running climate control @ max cool and tried to give speed to compressor through mini vci, but inverter output voltage remained at 33V. I've signed up for TIS and looking through wiring diagram to see where is the signal for the inverter to supply voltage (200V) to compressor comes from. I was thinking about forcing this signal and measuring amp draw of the compressor. Any constructive input is appreciated.
Just clear the code and see if it comes back immediately, or if it works then. Compressor is 3-phase motor and inverter can detect problem faster than you can measure anything. So you can’t measure the voltage. I don’t think there is just wire to tell it to turn it on. You can measure resistances of resistance of coils in the compressor, and resistance between them and body. And if you know enough you could drive compressor with something else, or measure current, taken by compressor, if system lets you turn it on.
put some UV dye in it the next time you fill it. at least then you'll be able to find the leak. the dye is so bright, most times you don't even need the UV light to find it.
I will try resetting the codes. I will check resistance to ground on the compressor. I assumed there has to be a "run request" signal from ECU for inverter to apply voltage to compressor and speed demand signal or may be just speed demand signal. Thats what I wanted to check.
The first time I had a loss of pressure, I vacuumed the system, refilled and added dye. No traces yet.
