Heater Temperature Full On or Off

Results 1 to 7 of 7
  1. #1
    CelicaSupra.com Member supraz's Avatar
    Join Date
    Jun 2003
    Location
    Vancouver, BC Canada
    Posts
    825

    Heater Temperature Full On or Off

    We took my wife's 84 out today and found a really odd issue.

    Heater Control Panel.jpg

    We found the air coming out of the dash vents was getting really warm. If we put the temperature knob fully left (20 which I assume is Celsius on Canadian cars) cool air would come out. Any position to the right of this and the air would get hot.

    I found that with the air flow control set to the full left (vents only) or to the full right (Defog) the temperature control worked properly. As I moved the temperature knob from left to right the temperature would go up in a linear fashion.

    With the air flow control set to blend (foot well and vents) or footwell only, the air would be cool when the temperature was set to the left side and full hot at any other position.

    Can this be the air blend flap not working in these positions? I have quickly looked at the TSRM and can make no sense of it.

    If the behavior was the same in all air flow positions I could understand a DVV problem, or ambient light sensor or ambient air temperature sensor.

    Before I haul the dashboard apart has anyone seen behavior like this?

    Any words of wisdom would be appreciated.

    Dale
    Black 1983 P Type 5 Spd, Cloth Interior, BBK,HRE 17" Wheels, HKS Exhaust
    White 1984 P Type Auto, Leather Interior, Sunroof, Digital Dash

  2. Remove Advertisements
    CelicaSupra.com
    Advertisements

  3. #2
    CelicaSupra.com Member supraz's Avatar
    Join Date
    Jun 2003
    Location
    Vancouver, BC Canada
    Posts
    825
    Well, the plot thickens.
    Last night I went outside to have another look at the symptoms and now the temperature is high on all settings.
    Then I tap the throttle and the alternator light comes on. At idle the alternator light is off.
    I go out again tonight and the battery is at 3.3V. I throw in another battery and it starts to drop from 12.7V to 12.2V in 2 minutes. I start the engine and the battery voltage is at 18V. I've blown a Voltage Regulator.

    I'm now wondering if the heater problems are due to the voltage being off.

    I've got another alternator coming in and will look at the temperature control issues once I've replaced that.

    Dale
    Black 1983 P Type 5 Spd, Cloth Interior, BBK,HRE 17" Wheels, HKS Exhaust
    White 1984 P Type Auto, Leather Interior, Sunroof, Digital Dash

  4. #3
    CelicaSupra.com Member SupraFiend's Avatar
    Join Date
    Mar 2003
    Location
    Vancouver, BC
    Posts
    10,042
    yeah you're symptoms are a little weird, definitely get that regulator working right first. Confirm your meter is working right too, I've had more of those fail on me then Toyota voltage regulators (I've had them fail, but usually its the caps).
    Black 86 mk2 Project Car
    New SDR 86 mk2 Daily User, Highway Cruiser AND Parking Lot Abuser in the works!

  5. Remove Advertisements
    CelicaSupra.com
    Advertisements

  6. #4
    CelicaSupra.com Member '82supra's Avatar
    Join Date
    Aug 2009
    Location
    Nova Scotia
    Posts
    3,795
    Check the water temperature switch, similar problems if lines A/B are reversed or valve malfunctions.
    Hidden Content
    DreadBull

  7. #5
    CelicaSupra.com Member supraz's Avatar
    Join Date
    Jun 2003
    Location
    Vancouver, BC Canada
    Posts
    825
    Well, the problem is gone.

    After doing some charging system work I warmed the car up and confirmed that the problem still existed.
    As per my last update, temperature is high on all settings of temperature setting and air flow direction setting.

    I pulled the rear part of the interior console and confirmed that the In-Car Temperature sensor was plugged in. I unplugged the connector and measured the resistance of the sensor which was 2.134 kOhms which translates to about 13 Degrees C which seemed about right. I plugged it back in and started the car up. It was still blowing hot air so I cycled the temperature control slider back and forth in case the resistance on the slider was intermittent.

    After thinking patriotic thoughts of the Queen and her Corgis for a while (Hey, the Queen is the monarch of Canada too you know), I brought the temperature slider down to the left side of the temperature range and moved the air flow control through all the settings and viola!

    It's now working. The temperature seems to be linear with the movement of the temperature slider. The higher the temperature setting, the hotter the air. The air is cold at the left side of the temperature range switch.

    I don't know if it was a poor connection on the In-Car sensor cable that I fixed by replugging or if the wiper contact on the temperature slider was open circuit and sliding it back and forth wiped it clean.

    Personally, I think it was the patriot thoughts! After all, how many 85 year old heads of state jump into an Olympic stadium and pull low? You may also not have noticed, but after the Queen and James Bond opened their chutes, there were three tiny little parachutes that followed them that were the Queen's 3 Corgis, Monty, Willow, and Holly. Don't mess with the Queen!

    https://www.youtube.com/watch?v=gfQY-YxX3CM

    Anyways, the temperature control is alive!

    Dale
    Black 1983 P Type 5 Spd, Cloth Interior, BBK,HRE 17" Wheels, HKS Exhaust
    White 1984 P Type Auto, Leather Interior, Sunroof, Digital Dash

  8. #6
    CelicaSupra.com Member SupraFiend's Avatar
    Join Date
    Mar 2003
    Location
    Vancouver, BC
    Posts
    10,042
    lol

    also, cranky old electronics. Mine does this sometimes too actually. Flicking the temp switch back and forth a bunch, eventually it starts to blow cooler air. Same with my cruise control, it likes to randomly stop working till like the 5th time I've flicked the set switch and toggled the system back on and off, then its fine till next time.
    Black 86 mk2 Project Car
    New SDR 86 mk2 Daily User, Highway Cruiser AND Parking Lot Abuser in the works!

  9. #7
    CelicaSupra.com Member Zerodrag's Avatar
    Join Date
    Mar 2003
    Location
    SoCA
    Posts
    460
    I think it could have been the slider contacts. I vaguely recall I had a similar issue at one point. I ended up spraying a crap-ton of that DeoxIt stuff into the slider area while moving them back and forth which seemed to have resolved the issue.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts