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Running the Prius without A/C

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by SaxPriud, Nov 17, 2021.

  1. SaxPriud

    SaxPriud Junior Member

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    my 2006 Prius has a non-working a/c system due to a leak around the evaporator. I am thinking of driving it on cold days when I only need heat (sub 60 F max temps). What's the best way to accomplish this so there are very few codes and annoyances, while also 100% ensuring the a/c compressor doesn't kick on and burn out? I am reasonably well versed in DIY Prius repairs, have a BlueDriver ODBC reader, but others will also be driving this Prius. If a simple removal of a relay or fuse will accomplish this, that would be the best. From what I have searched, I didn't find a straightforward answer.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    I don't think you could run the AC compressor with no gas in the system it's smart enough to not turn itself on there's a switch and pressure switch and all kinds of nonsense Even if it's a heat pump if there's no gas in the system there should not be voltage at the clutch to engage the system now if water just flows through a heater core and there's just a fan that should work no matter You should be able to turn the system on enough to turn the temperature up to high or 80 or whatever and put the fan on even if the yellow light comes on on the AC push it and it should go off Even if that yellow light comes on the clutch shouldn't be spinning or the compressor should not be on because there's no gas present I do believe this is correct

    SM-A715F ?
     
  3. MickyMatter

    MickyMatter Active Member

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    At the MFD you can switch on/off the A/C.
    But with every time pressing "auto" A/C will be enabled, too.

    So there can be several customer parameters be set by your dealer or someone with the intelligent tester.
    One parameter is called "compressor mode" which is "auto" by default with the above described behavior.
    It can be changed to "manual". Then A/C off will be off until you manually switch it on again.
    Then you can use auto with automatic regulation of temperature, humidity, outlets and fan speed except the support of the compressor. (of course you can manipulate temp, outlets, fan speed by yourself) For heating this should work well, for cooling only if there's cool enough air outside.

    SM-G950F ?
     
  4. mr_guy_mann

    mr_guy_mann Senior Member

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    IF the A/C system is completely empty then a pressure switch will go open circuit and the controller will not turn the compressor on.

    The problem can be IF the system is low on charge, but still has 40-50 psi. That's enough to allow the system to function, but lubrication for the compressor might be compromised.

    You could unplug the 4 wire pressure switch on the high side line, but you would have to seal the open connector and switch or things could corrode.

    Posted via the PriusChat mobile app.
     
  5. Tombukt2

    Tombukt2 Senior Member

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    Let the last little shot of gas out to the Schrader valve maybe I mean you're talking a squirt possibly a tad more to make sure it doesn't kill my system and just have to be if it broken an accident getting smacked in the front end it would be deemed okay

    SM-A715F ?
     
  6. SaxPriud

    SaxPriud Junior Member

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    Thanks! It’s been low for 18 months. The car sat parked and was driven (only by me) once in a while to keep the batteries in use. I would turn off the climate system right away. I have gauges to measure the pressure and I can do so.

    From your comment and others it seems it’s all good as long as the Freon has been completely expended. Is that correct? So there are enough failsafes built in that the compressor won’t come on?

    On a separate note, I am planning on doing the repairs myself. I had not been worried about compressor oil, and was only planning on adding the Freon only once I replaced the evaporator. How would I check the oil?
     
  7. SaxPriud

    SaxPriud Junior Member

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    Thanks. I was thinking the same!
     
  8. ChapmanF

    ChapmanF Senior Member

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    Why not just unplug the pressure switch?
     
  9. Tombukt2

    Tombukt2 Senior Member

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    Interesting note I've noted lately my car will not turn off ice at stoplight if heat is on no AC button light on just heat car stays running at stoplight if I turn heat off at light car Ice imed off . Heat on no stop ... Must be a heat pump or such. The blower is 12 cold but compressor is HV. No Defrosts are on or lit ..?

    SM-A715F ?
     
  10. dolj

    dolj Senior Member

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    If it is cold out, it usually does that while the car is still warming up. Once it has reached stage 4 of the warm up cycle it should shut down the engine as required. Until that time you can shut off the heat while stopped, as long as you can do without the heat while stopped.
     
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  11. Tombukt2

    Tombukt2 Senior Member

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    Well given there's no temperature gauge I don't really have any idea I have plenty of heat coming out the vents matter of fact it's 28° outside I have to turn the heat down to like 74 or I'll burn up and die like right now I'm pulling up to the stop light I've been running the car oh I don't know 30 minutes plus I pull up to the stop sign here on the main road and the car is just sitting here running running running I pushed the heat but I pushed the heat button off the fan button off button whatever and the car immediately dies of course no heat's coming out the vents but I don't care I don't know what stage I'm at I do know that plenty of heat is coming out the vents The radiator feels reasonably warm The engine is reasonably cold as always and the bottom of the inverters about 110 somewhere around there

    SM-A715F ?
     
  12. donbright

    donbright Active Member

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    if you have a obdii dongle and torque app on your smartphone you can read engine coolant temp, inverter temps, motor-generator temps, catalytic conveter temps, etc etc, and also if you dig deep there might be more info about what its doing.
     
  13. Tombukt2

    Tombukt2 Senior Member

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    Well that's pretty much no codes and the car is running great so generally I just make sure that heat of the air conditioning is not on when I come up to a stop That's easy to do in the winter Not going to happen in the dead of summer so we're doing fine 40 plus miles to the gallon not going to worry with it on a 20-year-old car kind of foolish to me

    SM-A715F ?