1986 toyota celica heating problems

I just purchased an 86 celica and I can't get the heat to work.I replaced the thermostat flushed the heater core and the fan runs on high only but it blows cold.The line going into the heater gets hot but the line coming from the heater stays cold. It is almost like it is not being pulled back by the water pump.Anyone know what I should do next........

Reply to
jpm7481
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If the line going into the heater core is hot where it enters the core and the line coming out is cold, there is a pretty good chance that there is a blockage in the heater core that flushing did not remove. If you want heat, you have to clear the blockage in the heater core or replace the heater core.

Check to make sure the system is properly bled and that there is a proper coolant mix. If straight water was used in freezing temperatures, there may be ice in the core.

Reply to
Ray O

When I flushed the heater core I hooked up my garden hose to the line before the valve and let it drain from the line on the coming from the core.It ran clear and showed no signs of any debris.If I let the car sit and run for a while the temp gets warm then goes cold very quickly.Do you still feel it is the heater core itself?

Reply to
jpm7481

You mentioned that the heater fan only runs on high speed, which is probably caused by bas resistors in the resistor pack. If the fan is running on high, it can suck all the heat out of the heater core. If the heater core gets warm and then cools rapidly even with the fan off, then the thermostat is probably stuck open, opening too soon, installed incorrectly, or is the wrong temperature range. Did you by any change remove the thermostat recently?

Reply to
Ray O

I just put in a new thermostat(correctly!) and new antifreeze(50/50).It just baffles me that the hot goes into the core but it is not coming out regardless if the fan is running or not

Reply to
jpm7481

When you installed the new thermostat, how was the spring oriented - is the spring up or down?

What is the opening temperature of the replacement thermostat?

Is the replacement thermostat OEM or aftermarket?

How is the temperature gauge on the instrument panel working? Does it read normal operating temperature or does it read cold?

Did the problem pop up after you drained and refilled the coolant?

Have you tried reverse flushing the heater core by disconnecting the inlet and outlet hoses in the engine compartment and sticking a hose in the heater core outlet hose?

When you flushed the heater core, did water pass through freely and did it come out clear?

Reply to
Ray O

The operating temp is always in normal range.The thermostat is installed correctly with fresh antifreeze.When I hooked up the hose to the core I ran it in the same direction as would go normally but saw nothing like dirt or chunks come out of it.It ran clear with water for about two mintues before I called it good.It did push out what seemed to be a correct amount of anitfreeze when the hose was hooked up.After replacing the antifreeze I ran the car until it was warm then felt the lines.The line going in was hot and the one coming out was cold like it was not being pulled out of the core by the pump.

Reply to
jpm7481

There is a metal tube coming from the back of the water pump that connects to the outgoing line from the heater core.Do you think that may be plugged or is that just wishful thinking?

Reply to
jpm7481

I asked all those specific questions because the answers could help me include or exclude potential causes of the problem, and because I do not know what your automotive experience or expertise is. I have seen incorrectly installed thermostats open and close to regulate engine coolant temperature properly but cause other problems, and aftermarket thermostats bring different potential problems.

It is normal for the heater core's outlet hose to be a little cooler than the inlet hose but it should not be cold.

I doubt if the water pump is the problem because the engine would overheat if it was not working.

Check to see if the heater core's return hose is collapsed, deformed, or kinked between the core and the engine.

If the hose appears to be OK, disconnect the heater feed hose at the water valve and disconnect the return hose where it enters the engine and see if you can flush water in both directions. I've seen stuff become lodged in the cooling system that only causes problems under certain conditions, which is why flushing in both directions may work.

Reply to
Ray O

Possible, but not likely.

Reply to
Ray O

I think I may have found the problem.the temp goes hot and then cold because the valve is opening then closing.I have actually removed the control panel from the dash and have it hanging by the wire connectors.When the temp starts to go cold I tap the control and it gets warm again.Not what I call an expert fix but at least I can get to work without freezing.You had mentioned a resistor pack.Where is that located in the car and is that something I can buy at an auto parts store.Again thanks for all the information.

Reply to
jpm7481

The blower fan is the fan that blows air past the AC evaporator and heater core. The blower fan speed is regulated by the resistor pack. Resistors reduce voltage by adding resistance to an electrical line, getting rid of excess juice by turning it into heat. The more resistors, the greater the voltage reduction, and the greater the voltage reduction, the lower the fan speed and the more heat is generated by the resistors. The resistor pack is located in the air flow out of the blower so that the air from the blower helps get rid of the heat generated by the resistors.

When the only fan speed is high, that usually means that the resistors have lost their ability to turn electricity into heat so all of the voltage reaches the fan. I doubt if you can buy a resistor pack at an auto parts store, but if you know how to solder, you can purchase the individual resistors at an electronics store and replace them. You have to look at the resistance of each resistor to find an acceptable substitute.

Reply to
Ray O

Make sure the resistors are constructed so as to handle whatever power you are asking them to dissipate. The tiny resistors that one finds used in low-power electronics, for example, tend to be good for only 1/10 to 1/4 watt (or used to be, back when I did a lot of that stuff). Resistors for "power" jobs should show very clearly what their rating is, fortunately.

Now to calculate the power handling. If the resistors are being wired "in parallel" (wire at one end tied to corresponding wires of all other resistors, with the same at the other end) then you should be safe in allowing for dropping the full battery voltage across the resistors; of course, in practice the fan will handle some of it. The watts dissipated by a resistor of R ohms when V volts are dropped across it are V * V / R. Do this sum for each resistor and it will give you the individual wattage ratings.

If the resistors are wired "in series", it gets more complicated than I think should be rushed through here. Parallel seems more likely to serve your needs.

BTW, large power resistors are often made to be bolted to a heat sink. It then becomes more of a construction project. Overall, it is probably best to try doing it as in the existing setup.

Ray can probably set yea/nay on this: maybe the shop manual says what the resistor wattage should be.

Reply to
Andrew Stephenson

Very good points! I was thinking more in terms of removing the bad resistors, taking them to an electrical supply store, asking them for suitable replacements, and re-soldering the replacements in the same location. Hopefully, the electrical supply store would know which replacements work.

Reply to
Ray O

Sorry, Ray - they're custom open wirewound nichrome resistance elements without any cases or markings, you aren't going to find any commercially available replacement parts to make one up.

If you knew the ratings for each section by measuring a good unit, you could make one up with several (guessing 10-Ohm to 25-Ohm range)

75W and 100W ceramic wirewounds, either the brown glazed vitrified or "sand bar" types - but the finished assembly will be paperback book huge. Will never fit through that itty bitty hole designed for a pack the size of an Art-Gum eraser...

To get the wattage density needed, it's designed more like an open electric heating element than a resistor - that's why it has to be mounted in the airflow right at the outlet of the blower motor. Even if the ductwork is partially clogged, the element will be cooled by the airflow turbulence churn zone around the blower wheel.

And you can't fix them, like the people who want to solder the breaks - most Nichrome alloys get brittle after they've been heated to operating temps, and always if they've been overheated past design temps, both of which are well above the melting point of soft solder. Silver brazing will take the heat for a temporary repair (if you can make it stick) but it's inevitably going to snap at another point.

Bottom Line: Go to the dealer parts counter, buy a new resistor pack, install it, and be done with it. It's not worth the time effort and heartache of reinventing the wheel.

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Reply to
Bruce L. Bergman

LOL! "Go to the dealer parts counter" is my usual response, I get "burned" when I stray from my usual practices!

Reply to
Ray O

I know, and I'm usually the one who says "If you can find a generic 'commodity part' that is OEM Quality and will fit and function properly, go for it!" - which is fine for batteries, tires, brake pads, hoses and belts.

The automakers don't make most of the specialized component parts themselves, they order them in bulk from various OEM specialty makers like Moog, Gates, TRW, Cole-Hersee, Briggs & Stratton (GM locks and switches) Monroe, Koni, Stewart-Warner, VDO, AUVECO (trim hardware), Nippondenso, Packard, Delphi, Autolite, Johnson Controls, Borg-Warner/York, Aisin-Warner, Buss, AEG...

But in this case, it ain't gonna work. You can spend $100 - $500 in parts and materials, and waste a hundred hours designing and installing a "bulletproof" resistor pack, and re-engineering the car to install it. Or better yet, put even more money and effort into a transistorized PWM DC motor speed controller, and save on the wasted energy through the resistor pack...

Versus spending (guessing $30) on a replacement factory resistor pack, and you can have it installed in 10 minutes. Done, and it'll likely last another 20 years.

If you were a dealer and sold a hundred resistors a year, it might make sense to track down the OEM maker who builds them for Toyota and order a case as needed - one layer of markup removed. Unless they're going for an obscene 200%+ markup, it's usually not worth the effort.

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Reply to
Bruce L. Bergman

I'm guessing closer to $60 on the resistor pack, but it is probably money well spent. In my experience, the folks who design Toyotas are pretty good at their job, and it is unlikely that I would come up with a better mousetrap for the same money.

Reply to
Ray O

There is a black plastic box mounted near the blower.Inside this box is three pieces that look like they have wound copper aound them.Is this the resistor pack that we are talking about? Thanks for all the info.It is of great help to me.I am what you might call a back yard mechanic but I don't try to rig things unless it is the only way to get by until the correct parts arrive.That is why I ask all the questions I can before getting myself into trouble.The last thing I need is to put the wrong pieces into this thing and have it do further damage!!!

Reply to
jpm7481

That sounds like the resistor pack if it is positioned so that the air from the blower fan passes over it.

Reply to
Ray O

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