Poor output from heater/defrost vents

[a.rogowicz]

I have a 1984 sr5 6-sp that i'm having issues with the heater/climate controls. Specifically the output from the vents. The blower seems to be working fine, i have separated the bottom housing from the blower and can feel substantial air flow, but from all vents it can barely be felt. the control cables, fresh/recirculation, warm/cool, and vent/heat/defrost, seem to all be in working order.

Any ideas? If anyone has a diagram of the inside of the heater control box, (the dampers, etc) that might help.

[Highlander]

Have you pulled the inlet off of the heater box (Passenger's side, Left, after removing the glove box), and checked that a) the cable is moving the flap to the open position, and b) that the heater core isn't all gummed up with debris?. You might also remove the cable from the heater control valve (in the engine compartment) and make sure that it is fully open.
My 85s have significant heating problems, my 83s were great about heating. Go Figure.
Archinstl had a thread on "Hotter heater hints" that you might do a search for as well

[ARCHINSTL]

The FSM available here has a section on the venting - but in the AC section at the end.
Also go to http://www.autozone.com/shopping/repair ... 5280052218; there are photos. Be sure to check out the AC section as well, as there are additional drawings of the system.

Similar to what Highlander mentioned, my then-new '83 had great heat, whereas my current '86 is, well, kinda tepid... I attribute that to at least several factors: The air has to blow through an AC cooling unit (none in the '83); the PO was a smoker and nicotine is presumably coating both the heater core and the AC evaporator; and just 22-years' worth of accumulated deposits. Does your car have AC?

As far as air flow - I always thought the '83 had better flow, even allowing for the above. It took a while, but after reading the OM again, and Typrus' (?) comments a couple of years ago, I realized that some air always came through the dash vents regardless of the control settings (and realignments); the way to increase flow to the floor or to the defroster vents was to shut off the flow to the dash vents by means of the vertical "dial" control.

Do keep us advised of your progress!
Tom M.

[Petros]

Remove as many of the ducts and covers that are easy to get to under the dash (it helps to remove the glove box and the center panel, not too hard), and inspect inside for debris and lint that could be blocking the airflow (a small mirror and flash light helps to look inside the areas you can not open up). Makes sure all of the ducts are connected and not damaged, you will need a strong flash light to look up under the dash.

Make sure the controls are actually actuating the flaps, the end of the cable can pop off sometimes.

Presuming you now get airflow, you can also enhance the heat output by flushing the heater core. If you do this carefully you do not need to drain the whole system, you just plug off the heater hoses. then you connect an extra hose to the heater and back flush it with soapy hot water at full hose pressure. Use another hose on the outlet side to run it into a large bucket so you can inspect it to see if there were many debris blocking the core (that is why you should flush it backwards). I have also used caustic chemicals, including Heavy duty Lime-a-way and even strait hydrochloric acid, though that is risky since it could corrode through a marginal heater core. But it works the best to remove scale and rust build-up. I fill the core with the caustic liquid through the hose and let it sit for about 5 to 10 min, and then flush it out with water, less time for the acid.

Make sure your hoses are not pinched and you have a good thermostat and you will have good heat.

[takza]

Use the FSM for instructions on how to adjust the heater controls? Pull and lube the control panel and ALL the cables. I did mine a long time ago and have had no issues since.

I would advice you NOT to flush the heating system with anything but water....you don't want to have to replace the heater core if you can help it...just my opinion. You might use distilled water with your antifreeze?

[otter63]

It's been two years now, so my memory of this is a little fuzzy, but the last time I replaced my blower motor, I pulled out as much of the ducting as I could and cleaned it out to make sure there was no dirt or mold. Noticed that some of the foam gaskets had deteriorated, so I got some adhesive weatherstripping (can't remember what thickness) and applied it in appropriate places. Airflow seems pretty good now.

Also, make sure your thermostat is working properly (not stuck open), otherwise the coolant won't get warm enough to heat up the car, especially when going downhill.

[ARCHINSTL]

. Presuming you now get airflow, you can also enhance the heat output by flushing the heater core. If you do this carefully you do not need to drain the whole system, you just plug off the heater hoses. then you connect an extra hose to the heater and back flush it with soapy hot water at full hose pressure. Use another hose on the outlet side to run it into a large bucket so you can inspect it to see if there were many debris blocking the core (that is why you should flush it backwards). I have also used caustic chemicals, including Heavy duty Lime-a-way and even strait hydrochloric acid, though that is risky since it could corrode through a marginal heater core. But it works the best to remove scale and rust build-up. I fill the core with the caustic liquid through the hose and let it sit for about 5 to 10 min, and then flush it out with water, less time for the acid.

Dumb question, but here goes anyway: Which is the inlet hose and which is the outlet hose?
Thanks...
Tom M.

[Petros]

not so dumb, until you know how it works: the inlet is the side with the control valve (with the cable that goes to the interment panel) that takes water from the back of the head (high pressure area). The out let is the other one without the valve that leads to, via a metal tube under the manifolds, the back of the water pump (low pressure area).

disconnect both hoses and add a long length of extra hose to each, hook outlet side up to hot water from a washroom sink or even the outlet on your hot water heater. Run the other into a bucket, and flush away. If you want to get more aggressive you can soak the heater core with strong soapy solution, or even strait vinegar (a mild acid), and then flush with hot water. Inspect the bucket for debris that come out to see if it was just mechanical blockage in the inlet side. On our Ford van I found a lot of paint chips plugging the heater core, probably from the engine.

I am starting to think my Tercel needs this same treatment, I only get med warm air out the heater, and everything else is new.

Good luck.

[Neu]

The only problem I have with my heater is that it's stuck on Face. The control fell off..so all I have is face heating, no defrost.

[terkill]

mine was too, sprayed some WD40 and used a needlnose before i found a replacement on ebay

[ARCHINSTL]

THANKS!
I hope to do this when it gets above freezing this weekend - gonna buy some new heater hose, just in case the original has deteriorated - although I hope to not replace it until Spring.
Tom M.

[takza]

The only problem I have with my heater is that it's stuck on Face. The control fell off..so all I have is face heating, no defrost.

If you can find the end of the cable that operates the door that controls air flow...you can manually move it to defrost....think it's on the pass side.

[xirdneh]

two weeks ago I had to replace the leaking heater core in my wifes car.
Shucks had one for 52.00, Napa for 69.00, and the local radiator shop 99.00.
i tried the Shucks core.
it looked exactly like the old one and the brand was something like "Ready R"
replacing the core was not much fun, removing the front seats made it more comfortable.

the heat output of the new core is about 60% of what the old one was.
all cables and flappers are working and valve is fully open
not sure whats going on except for the possible air bubble in core

de-soldered the old core to see what it looked like inside
some kind of hard white deposit around openings and several pieces of silicone gasket material hung up in several openings.
looked like it had about 40% blockage overall
but dang it, it still put out some good heat

tried soaking one end of old core in vinegar to see what would happen
nothing happened

[Highlander]

Xirdneh- That really sucks to have that as a result after that much work. Can you do me a favor and try something with that heater core though? On the spridgets list, there was a recommendation to try using a cola product to remove the deposits in radiators and heater cores. Can you spare a can of coke for an experiment? just a couple of hours at room temp to see what happens.

[xirdneh]

Xirdneh- That really sucks to have that as a result after that much work. Can you do me a favor and try something with that heater core though? On the spridgets list, there was a recommendation to try using a cola product to remove the deposits in radiators and heater cores. Can you spare a can of coke for an experiment? just a couple of hours at room temp to see what happens.

(old heater core with end caps de-soldered and removed)
i tried soaking one end of the heater core in some diet coke for about two hours
when i rinsed it off the slot ends were cleared
i will try the other end tonight

previously i mentioned soaking one end in vinegar for a few hours and not noticing any difference
when i grabbed the core for the coke experiment i noticed the deposits were soft
so i guess the vinegar did have some effect after all