Resetting the A/C screen

A while back a post was made about a Prime that had heated air blowing out the vents regardless of the setting. It was contagious. My 2017 Prime came down with the same affliction. The HVAC settings touch screen buttons didn't act right, no cool air, and the lower the temp setting the faster the fan blew (Auto-on) and the hotter the car got. It got even hotter with the gas engine running, because the heat pump compressor wasn't running at all.

I looked on youtube. I found a way to display the error codes on a regular hybrid Prius of the same generation. It involved, with the system off, accessory mode on, hold down the recirc & auto actual buttons while holding in the Power button. I tried it on my Prime with the touch screen "buttons." No codes displayed, but several of the touch buttons flashed on & off. Hmmm. Shut everything off, started up, and IT WORKED AS IT SHOULD!

Under the hood the low pressure suction line going to the compressor was nice & cold. Good. I borrowed refrigeration gauges from O'Reilly Auto Parts, and the pressures were just right, 30 psi for the suction and about 55 for the liquid line on this cool day.

The previous day's conversation with the dealership service writer will be in the comment box below.

 

When the problem got my wife's attention (didn't take long) I phoned the nearby dealership and spoke with a service writer. "Do you have a tech good with the Prime A/C system?"
He said, "Sure we do. I can get you in tomorrow (Saturday) morning." OK.

Took it in, told him that I though the problem was the control circuitry. I waited close to an hour, and the service writer came out and said that it needed a recharge of the refrigerant. I knew it didn't, because I had very briefly pushed down the core of the Schraeder valves in the service valves. Good sffft of gas from each.

I asked him what the pressures were. "I'll be right back," he said Waited. "They were 60 on the low side and 65 on the high side."
I said, "Those are the same (with minor gauge error). The compressor isn't running. It doesn't need a recharge with that pressure." (And you can't test much nor recharge with the compressor not running.)

Another wait. Then he said, "We can try a new compressor."
I said, "Just give me my keys back." And I left. They were just guessing. I'm not going to let them put in very expensive parts until they hit the right one, kind'a like the blind squirrel finding an acorn. The bozo forgot to put the dust caps back on the service valves. I'll ask them to mail the caps to me. Never forgetting that the service writer gets paid on commission, and the tech gets paid flat rate...no jobs, no pay.

I have a Universal reefer tech certificate for all types of reefer machinery. I've been doing reefer diagnostics and repairs since 1978 on units in size from water coolers to units with 500 hp drive motors. I've worked with several refrigerants...R-11, 12, 22, 502, and 134a in piston, centrifugal, and screw compressors. You can fill in the blanks with this fine old saying...You can't B.S. and old B.S'er.

 

The touch screen works for all other purposes.

The HVAC control screen crashed again, and I reset it again. I've an appointment with another dealership, and the trouble description is "the control screen won't start the heat pump."

Yes, the correct refrigerant amount is noted on a sticker under the hood, just over 1 kg. But if the pressures are normal for the temperatures then any deviation from the correct amount is not stopping the system from operating. If the not-running pressure was zero, it's a leak. If the system is cutting out on high or low pressure switches then the system has too much refrigerant (liquid filling part of the condenser) or too little (suction pressure is too low).