1. Frijjj

    Frijjj Member

    Joined:
    Aug 9, 2019
    51
    31
    0
    Location:
    Runcorn, UK
    Vehicle:
    2008 Prius
    Model:
    N/A
    It's cold in the cabin. No dash lights on 2008 Gen2 with 289,000 miles.

    It does get some heat after driving as the ICE warms up but it's never hot. It's just about ok with a thick coat on.

    The car has had the coolant flushed and a load of jelly like sludge came out of the heater core. It was initially blocked. Water pump, thermostat and new coolant all done about a year ago. I've got all the air out of the system using the lisle funnel and running the car.
    It does lose a bit of coolant but I can't find the leak. No pools under the car. I keep it topped up as the heating stops working totally when it's low on coolant.
    No mayo on the dipstick. I did find a little mayo under the oil cap. It has the cold start rattle so possibly the head gasket is on the way out.

    If the PTC heaters were replaced would that give me the extra heat that's missing? How do I test them to see if they are working?
    Any ideas appreciated
     
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    3,865
    3,807
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    Get a good thermometer that reads air temperature (not an IR thermometer) and a stopwatch or timer app.

    Position the thermometer in the airflow and start the car and the stopwatch.

    When the thermometer needle begins to move, note the time.

    Then let the car cool down again / next day:

    pull the fuse for the PTC heaters

    repeat the test.

    If the time-to-change is the same on both runs, your PTC heaters may need work. If it's faster with the fuses in, well... they're working great.

    In a normally working car you should see that needle twitch very quickly in response to the PTCs. It just doesn't move very far up because they are relatively small and weak- even at their best they only represent maybe 15% of the heating capability in the car.

    As with any car if you want instant heat, get an electric seat warmer. They can be added over top, or installed in your existing seat.
     
    Frijjj likes this.
  3. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    10,682
    7,840
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The PTC heaters make a very small contribution, one you can barely detect when they're working right. They max out at about 700 watts, or about half a hair dryer, compared to the roughly 5,300 watts worth of heat you get from the coolant when it has warmed up. They don't make the air out the vents feel noticeably warm.

    About the only way I can notice mine working is on a chilly morning with the windshield fogged; they do make a noticeable difference in when the glass begins to clear.

    If you use Techstream you can turn them on and off. If you have a DC current clamp over one of the supplying wires, you should see current flowing.
     
    Frijjj likes this.
  4. Frijjj

    Frijjj Member

    Joined:
    Aug 9, 2019
    51
    31
    0
    Location:
    Runcorn, UK
    Vehicle:
    2008 Prius
    Model:
    N/A
    Thanks for those. My Techstream is playing up (demanding a new code) so I will go with plan A
     
Loading...