Poor output from heater/defrost vents

[Neu]

i'd let it go until the water was normal for a minute or two. Color, smell even.

[Snax]

I wasn't really concerned with catching whatever came out of it, as obviously there was stuff in there, and just getting it to pass any water at all was enough for me to consider it a success.

All I did was pop the hose off from the head side of the inflow hose and the return side off at the head down below, then with mild water flow, just held it as tightly as I could against the lower hose for as long as I could stand it. (45F water onto bare hands in 50F = not wanting to hold it horribly long.) I then switched up and flushed it the normal direction before switching it to back-flow again. I'm pretty sure most of whatever was clogging it up came out the first time around, but it made me feel better to see it flow evenly both directions. I don't think I held it on there more than a minute in total with the direction switches.

I think it makes sense to include the flow control valve in the back-flush, as it might end up clogged as well from the reduced flow through the core.

If you are concerned about blowing out hoses or the core under your dash, it's unlikely to happen if you do it the way I did.

[takza]

Just remember that your water pressure is probably 3 or 4xs what your rad cap is rated for...so be sure you have an opening for it to go out of.

[Highlander]

I'm reviving this thread because I just got into the heater on the Yo D'or (due to NO heat during the recent below 0°F weather) and was able to go from no heat to bake me out heat. The car is an A/C car (or was if you read on) and since at our elevation, we rarely need AC, I'd already removed the belt and tensioner to gain MPG.
So I pulled the glovebox out and then went at the AC evaporator -I didn't know you have to remove the fan to get that out. Anyway, with the evaporator out, I could see that even though the fresh air flap closed when it was in the HOT position, the flap up directing all of the air through the heater core above was not closing. These two flaps are linked to each other, one on each end of a pivoting arm. So I readjusted the end of the cable that moves these two to seal of the flow around the heater core (An aside- this also means that the ambient air vent now doesn't open entirely-It'll need to be adjusted for summer driving), put in the factory non-AC interface from the blower, and TADA! I have bake me out of the car type heat!
Whether the flap closes completely or not can't be seen without removing the interface piece (or evaporator for AC cars). Those of you with marginal heat might take a look, the symptoms were that I had a breath of heat (the promise that if I were good, it might do something), but the higher I turned the fan up, the less heat I got (air was going AROUND the heat core, not through). There was just enough to defrost the windshield, driving at speed(40 60 mph) helped do this better. As the temperature got warmer outside, the heater SEEMED to do better (but it was just my imagination I'll bet).
The Yo D'or is now a non-AC car-since I had to vent the Freon to remove the evaporator, I just pulled it out and used the plugs and parts from the white '83 that's crunched, pulled the hoses and condensor, and when I next pull the radiator, the compressor's coming out as well- anyone want the parts?
Hope that this helps SOMEONE else suffering with little or no heat- it just sucks.

[ARCHINSTL]

Ahhh - so there are TWO flaps that are interconnected to the HOT/COLD pivot on the box? I had thought there would only be one.
I also noticed last night while waiting for a bit of a warm-up, that even with the control lever set to Defrost, there was still a LOT of air coming out the foot vents, so I thought I will fiddle around with that cable that controls all of the "position" settings to try to eliminate this floor output when the defrost option is selected.
I realize our systems are kinda primitive - but I just do not recall these problems with my then-new '83.
Since I rarely have anyone in the back seats, I just plugged those under-seat vents for more airflow up front - the "heat" these provided was minuscle anyway. I will remove these vents or permanently seal them at the heater box come Spring.
Thanks!
Tom M.

[Snax]

Thanks for the post Highlander! This is exactly what mine is doing now.

I get good heat with a low fan setting, but it diminishes to barely warmer than room temperature on a cold day with the fan on high. The engine cooling fan even kicks on when this is going on, so clearly, it's getting warmed up enough. I was thinking that maybe I needed to flush it again, but your experience has me thinking otherwise.

[Highlander]

Snax- I made sure that I had the engine warmed up before I started- That way I could be sure that the heater core was getting hot. When you remove the interface piece between the fan and the heater core box, you can put your hand on the core and tell whether its hot or not just to verify that the core is doing what it's supposed to.
I'm not sure why the two flaps aren't synchronized anymore, I'm sure that they must have been, but hey these cars ARE 30 yrs old, things change. You just have to hold the upper flap shut with the operator while you snap the cable housing back into place AND keep the cable on the actuator post (a little tricky, but what isn't )
The wife's car is next for inspection of this (at the least). I'll try to take some photos when I do it. I tend not to, 'cause I just want to do what I need to do and get on to other things (like building the new engine for the Yo Deux).

[Snax]

While I now wait for a shop to open up to get my front wheel bearings pressed out/in, I decided to dive into the flapper valve inspection and adjustment. What I found on mine is that the lower flap/core bypass was not closing very tightly - and only closed fully if I slammed the lever over to the right. Otherwise it would hang about 1/16th" open at the bottom. So I ended up adjusting the cable to make it close much more firmly now without limiting the ability to close the upper core flap.

It makes perfect sense to me now why such a small gap without the fun pushing air through it can create such an issue, as the control assembly for the lower flap is spring loaded and requires extra force to hold it shut. So if there is not enough spring pressure, as the fan speed increases, the lower flap gets forced open further, diverting a greater percentage of airflow away from the core. The bottom line is that even if the lower flap looks like it's closing all of the way, it's kinda like locking in a set of vice grips where you have to give it that extra little bit of pressure to hold it snug.

I also noted that the coolant flow control cable has a tough time moving the valve fully under the hood. Seems to be ok with the flow valve disconnected, so maybe it's just sticky. Either way, the mechanism behind the dash seems too flimsy to keep trying to operate it that way, so I left the flow control cable disconnected and moved the valve completely open.

I haven't had the chance to test how much heat I get out of these changes yet since my hub is sitting on the work bench, but I anticipate a very noticeable difference. Fingers crossed.

[takza]

Even a new cable needs to be lubed now and then?

[Snax]

True. Even one that appears to operate smoothly without a load can still bind up once you try to actually do something with it.

[Snax]

Now that I finally have my car back on the road again, I can confirm that the adjustments I made to the flap mechanism made the difference. From low fan to high, the temperature doesn't change from toasty warm. It's still not hot, but it starts to get warm within a mile of driving.

[Highlander]

I'm glad that it helped out , did you check the upper flap when you were in there? That's the one that diverts the flow through, not around the heater core.

[Snax]

Yeah, the range of motion on the upper flap was going fully to the stops both ways.

[sh#tbox]

You are not alone! I have a ouput problem as well. I have 2 of these one an 83 one an 85 the 83 has always worked great, the 85.... is stuck on face, and furthermore cold air blows out something under the passenger side, resulting in unhappy passengers! It sorta works defrost so I have not done much about it. I have taken the dash apart to see the controls, it is broken, but it does still move the cable. Think it's the re-circ one, you can hear it flapping too. the heat /cold works, the heater core does put out heat. it just does not go where directed! I found 2 ends to 2 of the cables they move and are connected, there is one that goes somewhere I have not found yet. There has got to be a broken plastic thing I have not found it yet.

My 83 will burn your feet off! this one wont even really do the floor, and its cold, on pass side

if anyone figures this out before me I'd like to know what it is!

[Snax]

Have you actually removed the ducting on the passenger side to see the flaps in action? That's really the only way I can think of to verify the ones controlling core flow are working properly. Make sure the lower one seats FIRMLY.