Transducer for Comfortron Part I
Posted: Thu Nov 13, 2014 8:31 pm
I posted this on the FB site earlier. Thought there might be some here that were interested, or know more about this than I do. Here are some pictures of the transducer unit for Comfortron Automatic Climate Control in the Toronado (same at least for 66-68). The unit is mounted on the firewall passenger side (interior, just below glovebox). These units convert voltage to vacuum. The vacuum controls the lever on the Power Servo mounted on the air handling box in engine compartment. Essentially, input from the control unit on the dash and the 3 temperature sensors in the car give a particular voltage. The particular voltage running through the very thin wire causes the wire to contract to differing amounts causing no vacuum bleed off or some vacuum bleed which causes the power servo arm to position in 3 basic steps, thus operating a different set of vacuum valves to open (a stator moves position with the servo arm). Anyway, the transducer is simple really in design. The issue with these is the vacuum diaphram in most cases I think. mine had a small hole in it so it didn't work. I tore it apart and here are the pieces. If there were a way to make the special diaphram, these could be repaired. The FSM just says to replace the unit if it fails -- there was not repair kit for these. Read the picture annotations if you want more info.
Transducer taken apart. The vaccum end is clearly evident. It is held on with two screws. You have to loosen the electrical end so the wire loop can move the direction to be careful when disasembly occurs to not break the thin wire. For the vacuum end, there is a brass fitting with an o-ring to seal it to the small vacuum tube end. The little copper ring (castle ring) is pushed into place to hold the brass/o-ring piece tight agains housing. The other parts above teh wire loop are all parts of the diaphram spring assembly. The end wire is bent a little, but it goes through the hole in the previous mentioned brass fitting. The wire loop is held by a metal piece that fits in the diaphram and allows air to bleed through to reduce vacuum. As the wire contracts when voltage is applied, it pulls the diaphram spring forward, sealing the diaphram and the power servo arm gets full vacuum. When the wire is relaxed and there is little or no voltage applied, the diaphram spring relaxes and seals the small bleed hold in the diaphram. The power servo arm gets reduced vacuum and moves to a different position.
The wire of the transducer. Looks like a bimetallic setup -- different conductivity of different metals. You can see the metal piece that catches the wire loop at the top right. This piece also fits into the top of the diaphram unit opposite the spring side. When the wire contracts, it pulls the diaphram towards the wire loop sealing off the bleed valve. When there is little or no voltage across the wire, it relaxes and the bleed valve opens thus causing reduced vacuum to the power servo arm and causing that to move and the stator as well.
- Transducer 1.jpg (74.31 KiB) Viewed 15991 times
Transducer taken apart. The vaccum end is clearly evident. It is held on with two screws. You have to loosen the electrical end so the wire loop can move the direction to be careful when disasembly occurs to not break the thin wire. For the vacuum end, there is a brass fitting with an o-ring to seal it to the small vacuum tube end. The little copper ring (castle ring) is pushed into place to hold the brass/o-ring piece tight agains housing. The other parts above teh wire loop are all parts of the diaphram spring assembly. The end wire is bent a little, but it goes through the hole in the previous mentioned brass fitting. The wire loop is held by a metal piece that fits in the diaphram and allows air to bleed through to reduce vacuum. As the wire contracts when voltage is applied, it pulls the diaphram spring forward, sealing the diaphram and the power servo arm gets full vacuum. When the wire is relaxed and there is little or no voltage applied, the diaphram spring relaxes and seals the small bleed hold in the diaphram. The power servo arm gets reduced vacuum and moves to a different position.
- Transducer 2.jpg (72.48 KiB) Viewed 15991 times
The wire of the transducer. Looks like a bimetallic setup -- different conductivity of different metals. You can see the metal piece that catches the wire loop at the top right. This piece also fits into the top of the diaphram unit opposite the spring side. When the wire contracts, it pulls the diaphram towards the wire loop sealing off the bleed valve. When there is little or no voltage across the wire, it relaxes and the bleed valve opens thus causing reduced vacuum to the power servo arm and causing that to move and the stator as well.