Hi I am new to posting here. I hope someone here can solve my proble before winter. My 79 244 dl never had any working heat or air. What it did have was air coming from outside through the vents to heat the inside really well from all vents, even the defrost, but it only works when the car is moving, which is good enough for me. The problem is that it stopped. No air comes from the vents at all anymore while the car is in motion. Can someone please help me in figuring out why? Thanks

 

You will likely have better luck posting your car questions in your cars area instead of "New Member". That's just to introduce yourself and your car to the group.
I've moved it for you.

 

any number of things could be wrong. the airflow control flaps are vacuum operated, it sounds like yours were all open before, but your fan isn't working. the fact that you had air when moving before., but none now suggests that maybe the 'recirculate' flap closed, so instead of fresh air flowing through the car, you're getting nothing now (since the fan is apparently dead).

there's a vacuum hose from the engine, through a 1-way valve, through the firewall that goes to the air/heat vent control unit on the dashboard. chances are this is disconnected if nothing is working.

240 fans are a pain to replace as they are behind the center console.

the actual amount of heat you get (not air volume but temperature) is controlled by a heater valve that's just right of the gas pedal, this heater valve is cable operated via the cold/hot lever... older models had a thermostat regulated valve that often failed such that you get no heat or full heat but nothing in between.

 

thank you so much

 

wow, what a wealth of knowledge here on this website. Thank you guys so much for helping me with my problem.

 

k, I'm not real familiar with the early 240s, I have only worked on my 1987 but they aren't *that* different.

it looks like the early ones had a couple versions of the COMBU heat/ac controller. there's 3 buttons in the middle, either FLOOR, DEF, and REC or graphics for the same, these work vacuum flaps in the air boxes behind the dash, and control where the air goes. there's a slider on the left of the control panel, this opens/closes the heater valve via a steel wire ('bowden cable'). on the right, is the fan switch, and there's a couple versions of those, 3 or 4 speed.

the vacuum from the engine intake manifold goes through a one-way valve into a plastic 'egg crate' vacuum bottle before getting to the pushbutton vacuum valves.

I would get a "Mity-Vac" to debug this... thats a combination vacuum gauge and hand pump. get behind the dash, find the vacuum line that goes into the one-way valve, and hook that line up to the mityvac, start the engine, do you have vacuum? (-8-10 PSI is typical at idle)

engine off. push all 3 buttons so they are out, now hook the mityvac up to the one-way valve and storage bottle, and pump it a enough times to see if holds a vacuum? if it does, try the 'RECIRC' button and pump a bit more, do you hear the flap open ? you might have to keep pumping to maintain a vacuum on the system as you work controls, but either in or out if you're not changing it, there should be no leaks, and it should hold steady vacuum.

the exploded parts diagram of the early 240 COMBU HVAC is something like this...


(I don't think thats exactly your year but the general idea is close)

engine intake manifold vacuum comes in on 34 but that picture doesn't show the early 1-way valve there (but someone may have installed one under the hood where they put it now). the vacuum 'storage bottle' is 35. 2 at the bottom is the vent and heat control... the heater valve is 13. the fan motor is 40, it has two fans 44, one on each side in the ducts 5a and 5, the motor fits inside of housing 3+4. 28 is the heater core which fits inside of housing 3 also.

fresh dashboard air goes in at 54 on top, flap 10 controlled by vacuum actuator 6 chooses fresh air versus recirc (cabin) air intake to the fan.

the fans inside the housings 5 and 5A blow out both the top and bottom, where there's (not shown here) more pipes to different vents (bottom goes to the floor heat, top goes to the dashboard and defroster), the flap 50 actuated by 11 controls the floor air...

the airbox 3+4 and everything in it including the fan motor and heater core is directly behind the center console of the dashboard.