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Tue Nov 22, 2016 10:53 am

So I have a 73 squareback, just got it, haven't gotten too deep into the cars main body but the heater and defroster don't work when I pull the levers. Any ideas how??

Tue Nov 22, 2016 12:14 pm

I have a 71 but got really deep into the heating system just about month ago. And since all these cars a similar can't imagine that great of a change between 71 and 73.

Go to engine and make sure your fan housing is connected to the heat exchanger. [random pic of heat exchanger from gallery but should look similar]

Check under the back seat and make sure that heater is connected by a couple insulated black y shape boxes. [random pic from gallery but should look similar]

If all connected, remove one of the black boxes and while the car is running feel if air is following from the engine bay into the cabin.

If no flow, on the heat exchanger a cabled should be connected to lever that you opens a baffle for air to flow. you can see it at the right most end of the picture above.

If that is connected and opening, then there is a connection deep under the car next to the cabin connected by a tube to the heat exchanger that has a thermostat for hot/cool air mixture that I have read it can get stuck but not sure if that would effect air flow. Just something to be aware of.

All this to say, I bet the cable is broke or disconnected to the baffle on the heat exchanger.

Tue Nov 22, 2016 12:48 pm

Joliver5 wrote: So I have a 73 squareback, just got it, haven't gotten too deep into the cars main body but the heater and defroster don't work when I pull the levers. Any ideas how??

Follow the air path. The air for the heat/defroster is the provided by the engine cooling fan on the crankshaft. So the volume of air will vary with engine rpm.

Air is ducted from the fan housing to the heat exchangers. If some dope has replaced your heat exchangers with J-tubes, you won't have heat at all.

The exhaust passes through a pipe within the heat exchanger and the fresh air from the fan is blown through the sheet metal portion of the heat exchanger where the hot exhaust pipe heats it up.

At the front end of each heat exchanger is a cable-operated valve. These should be connected via cable to the on/off lever between the seats. This lever determines the volume of heated air that enters the cabin.

From the front end of each heat exchanger there is a tube that brings the hot air into the cabin under the rear seat. If you lift up the rear seat you will see the tubes on each side. It splits under the rear seat with some air going to the outlets in the rear seat kick panels and some going into the heater channels in the rocker panels.

The rear seat kick panel outlets are controlled by the other lever between the seats. There should be a cable that closes those outlets when the lever is moved to defrost.

Now the hot air is moving through the heater channels in the rocker panels to the front footwell vents. If your heater channels are rusted out this is where you lose all the hot air.

If the heater channels are good then you should get hot air out of the front footwell vents. Another tube on each side carries the hot air up to the defroster vents at the base of the windshield. When you move the lever to defrost it should close all the footwell vents (via cable) and that way you get full defrost to the windshield. (Depending on your year, you may have a knob on each side to manually close the front footwell vents)

Note that the round vents on the dashboard, the fresh air control knobs on the dashboard, and the fresh air fan on the dashboard have nothing at all to do with the heat. Those are for fresh air (i.e. unheated outside air) ventilation only - the intake for that system is the cowl vents just forward of the windshield.

So the best way to figure out what you have and where the problem is is to start at the rear and follow the air flow forward to find out what's missing.

Tue Nov 22, 2016 1:26 pm

Thank you for the replies. I will probably try and see what the car is missing. Do either of y'all know also where the horn itself is placed on the 73 squareback? I have heard that it's under the front bumper but I don't know for sure.

Tue Nov 22, 2016 2:08 pm

The horn is normally mounted on the front driver side bumper bracket.
P.S. Your '73 got the 1 year only high speed transmission with 3.88 ring & pinion!

Tue Nov 22, 2016 10:14 pm

Does anyone know if I would need a new heater if there are no J tubes, and there is a heater box that just needs to be replaced, which I would need? Poking around the internet I have found like a left and right one. Or would I not even need one?

Tue Nov 22, 2016 10:25 pm

Show us pictures of what you've got.

Wed Nov 23, 2016 4:28 am

sjbartnik wrote: Joliver5 wrote: So I have a 73 squareback, just got it, haven't gotten too deep into the cars main body but the heater and defroster don't work when I pull the levers. Any ideas how??

Follow the air path. The air for the heat/defroster is the provided by the engine cooling fan on the crankshaft. So the volume of air will vary with engine rpm.

Air is ducted from the fan housing to the heat exchangers. If some dope has replaced your heat exchangers with J-tubes, you won't have heat at all.

The exhaust passes through a pipe within the heat exchanger and the fresh air from the fan is blown through the sheet metal portion of the heat exchanger where the hot exhaust pipe heats it up.

At the front end of each heat exchanger is a cable-operated valve. These should be connected via cable to the on/off lever between the seats. This lever determines the volume of heated air that enters the cabin.

From the front end of each heat exchanger there is a tube that brings the hot air into the cabin under the rear seat. If you lift up the rear seat you will see the tubes on each side. It splits under the rear seat with some air going to the outlets in the rear seat kick panels and some going into the heater channels in the rocker panels.

The rear seat kick panel outlets are controlled by the other lever between the seats. There should be a cable that closes those outlets when the lever is moved to defrost.

Now the hot air is moving through the heater channels in the rocker panels to the front footwell vents. If your heater channels are rusted out this is where you lose all the hot air.

If the heater channels are good then you should get hot air out of the front footwell vents. Another tube on each side carries the hot air up to the defroster vents at the base of the windshield. When you move the lever to defrost it should close all the footwell vents (via cable) and that way you get full defrost to the windshield. (Depending on your year, you may have a knob on each side to manually close the front footwell vents)

Note that the round vents on the dashboard, the fresh air control knobs on the dashboard, and the fresh air fan on the dashboard have nothing at all to do with the heat. Those are for fresh air (i.e. unheated outside air) ventilation only - the intake for that system is the cowl vents just forward of the windshield.

So the best way to figure out what you have and where the problem is is to start at the rear and follow the air flow forward to find out what's missing.

This is great, the only bit I would add to it is you have plastic ducting that runs under the dash from where the heat is channeled upwards from the heater channels. In my case this was missing and I had to find the various pieces to make it work right. There is an illustration in the Brown Bentley book of all the bits needed.

Wed Nov 23, 2016 8:51 am

You had better buy this brown Bentley manual quickly if you are going to own/drive a Type 3. My used 1974 edition has the color wiring diagrams!
https://www.amazon.com/gp/offer-listing/083760057X...ition=used