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Heater Core??

Discussion in '80-Series Tech' started by 3sacrwd, Feb 10, 2004.

  1. 3sacrwd

    3sacrwd

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    Seems like my heater doesn't get too warm in the wintertime...Could it be a clogged heater core? The auxilliary heater does get pretty warm, but the main heater stays pretty close to luke warm. The engine heats up to normal temp. I tried to tape a lrge piece of cardboard over the radiator, but that didn't get it any hotter any faster. I would hate to have to pull the heater core unless it will do some good. Thanks for the help.
     
  2. Rookie2

    Rookie2

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  3. 3sacrwd

    3sacrwd

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    Thanks R2,

    I will check my switches, but it seems that everything is moving around all right The heater under the Passenger seat heats up well, but just coming out mediocre at the vents.....I did a search on "Heater Core", but missed the one you sent. Thanks for the help. By the way, what does FSM diagnostics mean??? I spend more time trying to keep my 87 Vette up and running then the TLC. ........"Squeeky wheel....etc." :-\

    Thanks
    Kevin
     
  4. IdahoDoug

    IdahoDoug

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    Kevin,

    What year, what country, what model, etc? Also, what do you mean by "main" heater and "auxiliary" heater. Finally, are you saying you have a heater under the passenger seat??? Huh?

    DougM
     
  5. 3sacrwd

    3sacrwd

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    Sorry, I updated my profile to reflect the correct information.........The heater under the passenger seat blows air into the back middle seat area.......I did
    not think that this was that unusual.........Sorry for the "newbie" questions...we all gotta start somewhere. Thanks for the help.
     
  6. PHAEDRUS

    PHAEDRUS

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    3sacrwd
    couple things to check out first.
    1. heater flow valve. this is located on the firewall right behind the number 6 cyl. if you follow the two hoses down the side of the mighty 3fe you will see it. pull this off and make sure it is opening and closing fully. if so go on to step 2.
    2. remove the hose from the mixing valve to the firewall, alos remove the output hose from the firewall back to the coolant res. grab your garden hose and see what comes out of it. I highly recomend after doing this you have the cooling system flushed to get rid of any deposits anywhere else in the system. the heater core is a low spot in the cooling system so goo likes to collect there.
    3. if 1 and 2 dont get you set right step three is to go into the core. I would try at least 1 and probably 2 before I go seating the heater core.
    as to the second row heater I dont beleive this has a mixing valve on it at all. if memory serves this is a constant hot line out. I think with your symptoms it is probably the valve on the firewall but I include the others just in case this doesnt fix it.
    Dave
     
  7. 3sacrwd

    3sacrwd

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    Thanks Dave,

    I will give it a try when it warms up a bit here. I will let you know my results.

    Thanks again for the help.
     
  8. 92Cruiser

    92Cruiser

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    My 92 had very little heat the first winter I had it. I replaced the thermostat and she burns my toes now. FYI on your 3FE, if you do replace it yourself you only have to drain a few inches of coolant out of the radiator. The thermostat sits pretty high up.


    Brian
     
  9. PHAEDRUS

    PHAEDRUS

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    Thanks brian I totally spaced that aspect.
    3sac no problem i had the same issue on my 87 mini truck and the flush solved it.
    back to the issue at hand if your coolant is anything but bright red or bright green flush it the 3fe is great but the cooling system is a bit finicky.
    Dave
     
  10. IdahoDoug

    IdahoDoug

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    Kevin,

    I'm still lost here but will try again for humor's sake:

    "What do you mean by "main" heater and "auxiliary" heater.  Are you saying you have a heater under the passenger seat?"

    The reason I'm trying to find this out, is I believe you do not have a heater under the passenger seat. I think you're referring simply to the hot air vents that come out under the passenger and driver's seats to provide 2nd row heat. If these are hot, you do not have a heater core problem, a blocked line to the heater core, or a blower problem because these vents source their heat from the same place as the dash vents you're complaining about. This may be a completely normally operating system that Toyota designed to put more BTU's into the lower part of the interior than the upper part of the interior. A poor thermostat may cause this difference to be more than normal, however.

    In the absence of any input on your part, I will assume you have a factory rear heater, which puts air out the vents at the bottom of the center console's rear edge and has a switch at the lower dash center (Hi/Low). Correct?

    The reason for the confusion, is that I believe some older LandCruisers indeed did have a heater under the passenger seat, and it was referred to as an auxiliary heater for cold climates. HTH.

    DougM
     
  11. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    Doug,

    The 80 series vehicles have a "rear heater assembly" that is mounted under the RH front seat. It has it's own core and fan assembly. It is controled by the Hi-low switch you mentioned.
     
  12. Beowulf

    Beowulf

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    >> what does FSM diagnostics mean??? <<

    Kevin,
    FSM=Factory Service Manual. There is no substitue for the Toyota manual for your year model. There are some specific diagnostic tests for the heater. Step 1, step 2, step 3...
    -B-
     
  13. IdahoDoug

    IdahoDoug

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    Cdan,

    Thanks for the clarification - thought the rear heater was in the center console. So Kevin - compare the heat output of your front footwell heater vents (under dash venting into footwells) with the heat output of the dash vents you're concerned about. If the foot vents are hot enough for you, but the dash vents are not as hot, then you're getting plenty of heat out of the heater core. It may simply be that the dash vents mix too much fresh air on the way into the interior from the factory.

    DougM
     
  14. PHAEDRUS

    PHAEDRUS

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    Doug,
    to clarify a little further. I only know that this is correct for a 92 and will assume for a 91 as well but there is a rear row heater wich has its own core but is supplied by the control switch on the firewall. (I just went out and checked to make sure) SO..... if the heat output at the rear is higher than the heat output on the front the front heater core sounds like the likely culprit. I am not sure if there is an internal mixing valve in the heater body(other than the firewall mounted one) that would be suspect but more than likely it is the front heater core.
    Dave
     
  15. ppc

    ppc M Go Blue

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    There is an internal mixing valve. Earlier in the season when I replaced all the heater hoses and flushed the system I didn't finish it all before dark. I needed heat in order to drive it that night so I temporarily connected the hard pipe output of the PHH directly into the heater input without using the firewall valve. I was thinking that I would be blasted away with to much heat but I was surprised that I could control the heat just as normal. I’ve never paid attention to that valve to see if it ever is in a partly open state but I’m guessing not.

    The solution to the initial problem would lie in the innards of the mixing valve inside the front heater assembly.
     
  16. 3sacrwd

    3sacrwd

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    Thanks for all of the posts...Yes, I have the factory Heater under the RH passenger seat, which does have the Hi/Low switch on the dash. This heater gets hotter faster and puts out hotter air than the dash vents. So, does this have it's own heater core or not.....I only have a Haynes manual, not the FSM, and I dont believe it says it in there. I will check the heater valve and change the thermostat, and drain and replace the antifreeze this weekend. I will respond and let ya know if it helped at all.....Kevin
     
  17. IdahoDoug

    IdahoDoug

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    Kevin,

    Do a search on "flush" to get some useful tips on properly cleaning out your system - especially draining the block and not combining different coolant types.

    DougM
     
  18. CDN_Cruiser

    CDN_Cruiser

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    waaaaaaaiiiitttttttttt, late to the party again!

    See the post noted in this thread (my experience).

    If you are getting to op temp and rear heater is working, the first thing I would do before pulling any hoses, etc is check the cable coupling at the valve that controls the flow of coolant into the heater (sorry I don't have the FSM in front of me, so no official name). From the post noted above I think we're talking about the same thing - follow the hose at the very top of the firewall aft of the engine there is a valve in line with this hose that should have a pin on the bottom and a cable linked to this pin - I spotted the problem instantly when I opened the hood.

    In my case the cable had slipped off (a retaining clip had come undone). This is the cable that is linked (via servo? or maybe manual) to the temperature contol. So, despite moving the temp control to 'hot' it was still very cold as the valve was stuck in the closed position. All I did was manually open the valve (no tools, no removing anything) and - very hot air blowing in the cab.

    I hope this works for you!

    Cheers, Hugh
     
  19. ppc

    ppc M Go Blue

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    The valve which you are speaking of on the firewall controls the flow to both front and under seat heaters. Yes the underseat has its own core. The tubing to the under seat heater uses 3/8" tubing and the front heater is 5/8" which should provide a higher capacity. There is definitely a problem with the front heater and I would guess it to be something other than the heater core. You really need to read the factory service manual as the front heater contains three servo motors and about 10 dampers and to say the least is very complex.