hot air all the time

[7783911]

I recently changed the under dash outlet and noticed that hot air is blowing out regardless of my two pull handles between seats being "closed" (down) which I always thought closed the flappers from the heat exchangers?

on top of that my top slider which control free air flow can be slid from left (little open) past middle (which is indicated as fully open) and can actually slide and push the fan speed to the right.

so sound like i have two issues

hot air flow when there shouldn't be
a fresh air control that may be suspect

advice on where to start...i was thinking to remove the frunk blower cover and see if the cables are not correctly adjusted? or should I start at the heat exchanger?

all advice welcome

bob

77 targa (83 sc engine), SSI heat exchangers

[darrin]

believe your second issue is normal -- your first issue (always heat) ls likely caused by rusty/dirty/misadjusted heater flapper boxes under your car -- see 1987 911 Always blows hot air in cabin

[Solamar]

I'd also agree that the second issue is normal.

I recently rebuilt the blower assembly in my 78 and was very careful to adjust the cables correctly.

My top lever, if pushed all the way to the right, pushes the fan lever on.

[tratza]

I rebuilt my entire AC system last year (thank you Griffs) and on the first or send drive noticed hot air coming out of the drivers side vent and luke warm air out of the drivers dash vent. Turned out one of the new AC hoses was catching the hot air vent flow valve. Bent the wire and all good. Thank you Griffiths. Nice and cool on hot Texas summer days even in a Targa.

[7783911]

thanks all..the links were especially helpful, i will lift my rear this weekend and take a look but i dont suspect the flappers because i didnt have this issue until

recent top end rebuild with engine out and back in
fixed the ventilation controls as a tab was broken which may have altered the cable positions? (unlikely but suspect)

My understanding is the flapper box controls by pass of hot air from SSI exchangers to either vent to outside or to run to frunk ventilation system where individual falppers exist for left and right. In additional reading it states that these boxes (frunk flappers? or controls) can produce a mix of air which is a tad confusing?

so..easy start is to look at flapper boxes then work forward from there..wish I had a lift now.

one question, does anyone know if the large spring on the flapper box is available for replacing? Part #?

[shadowjack1]

Spring part number is 999-522-023-00 OEM

[shadowjack1]

By the way I had the same problem after an engine reinstall . Turned out that the cable was caught on some transmission part pulling the flapper open. The levers did not operate at all. They went up and down but not working the flapper box.

[tcar]

Originally Posted by 7783911

I recently changed the under dash outlet and noticed that hot air is blowing out regardless of my two pull handles between seats being "closed" (down) which I always thought closed the flappers from the heat exchangers?

Flappers send heat to the cabin when CLOSED.

To stop the hot air in the cabin, the flappers should be OPEN.
That way the heat is directed outside, instead of into the system.

[7783911]

Yes, i was just dyslexic in my statement..open (levers down) has flapped diverting hot air to outside under the car. Understood

[gerben1986]

Check if the cable moves at the boxes if you're adjusting the lever. I had the same issue and replaced the cables because they were stuck in their hose.

[megerian]

Some added info here

unwanted heat

[MichaelSJackson]

If the flapper is not seated 100%, then you'll get hot air. I had this problem and my first inspection led me to believe they were fine. But they were "almost" closed. If they are closed, then there is no way heat can get to the cabin. The pin hinge can be stiff. The return spring can be corroded and not able to pull completely closed. The control cable can be bent. The collar connecting the cable to the flapper can simple have slipped.

And only one of them has to be partly open, for you to get heat.

[PFNog]

I had a similar ‘heat always on’ problem in my ’87. It started immediately after I’d been doing some work on the sway bar mounts – in the general vicinity of the flapper boxes.
As it turned out I’d accidentally knocked loose one of the flapper cables. They work kind of like bicycle shifter cables and need tension on the housing for them to stay in place and work properly. I must have nudged it out of place when working down there and all it took was a one-second fix of placing the housing back in its little seat. Working perfectly again after that.
So I’d suggest looking at the cables first. Btw, If only one side (passenger or driver) is always on, then likely the cable is disconnected at the flapper. If both sides are ‘always on’, then I’d look at the control side of the equation and see if something got dislodged there.
Assuming the heater controls worked fine before you did your work, it’s more likely something got unhooked while you were working on your HVAC system than it is that your flapper boxes suddenly got rusty and sticky … IMHO

[7783911]

so far only visual inspection and driver side the bypass gate is open but not 100% (90-95%) so I will first lubricate and work that in the try but i fear the internal may be in need of attention as well which means pulling off the flapper box...something i think a hoist would make a lot easier so checking around when i can use one some friends have

[7783911]

PF

i assume you had to remove the flapper box to get to all the components,,,any easy trick to pass along...looks like a &^%$# to do with the car on jacks versus a lift?

[PFNog]

Actually the cable is easily visible at the flapper box. A lift makes things much easier,sure, but you can see the cable without one. I just took this photo in my driveway...crawled in behind the rear wheel - sorry, it's a little out of focus (iphone) but you can see the cable - I circled the part where the cable came loose from its tab. So if your cable looks like this, then it's not the problem... if it's not in the tab, then bingo!