I’m sure that I’m not the only Triumph enthusiast who has experienced the frustration, or should I say “Frostration,” of a heater fan that has ceased to function.
Usually, the cause of this problem can be traced to leaves or some other foreign debris that has entered the ventilator scuttle that is located in front of the windscreen (the black plastic rectangular grill held in place by 2 screws).
Not only will this debris bind the heater fan, which will eventually burn out the armature winding, but it will also clog up the drains at either end of the plenum. (The plenum is the tunnel that is behind the firewall and in front of the dashboard.) It is an air intake, and it houses the windscreen wiper gearboxes.
Did you ever wonder where the water that enters that vent goes? Ideally, and I use the term loosely, it is supposed to drain through two 1/2″ inside diameter pipes, one at either end of the plenum. Are you ready for this? It then goes into the inner fender. The engineer who designed this must have been suffering from a post-Boxing Day hangover. When I restored my TR-6 I found 3″ of leaf debris sitting in there rotting away the rocker panels and fenders.
The hoses that the water flows through are visible from inside the car. If you lay in the footwell on your back you’ll see a hose going through a hole on the upper part of the inner front fender, just ahead of the “A” post, on both driver and passenger sides.
If the situation s bad, like mine was, you’ll pull on the hose and the metal extension from the plenum will break off and a quart of black, smelly liquid will pour onto you and your new English wool carpet. If you think there is water trapped in the plenum, remove the carpet, and have a coffee can ready to catch the water.
Now comes the hard part. You must tap this hole out and insert a brass fitting. I was able to obtain the tap and brass air hose lilting at a hardware store. Make sure the thread sizes are exactly the same. I also used silicone sealant on the threads, and then I shot the hole with Rustoleum primer.
If there is debris in the plenum, vacuum it out, let it dry thoroughly, and then spray the inside with Rustoleum. I used the nozzle and extension from brake cleaner to shoot the paint all the way into the plenum. Shoot paint into the plenum until it starts to drip out of the brass fitting. Now you won’t have to worry about it rusting out again.
I then used clear surgical tubing to carry the water from the brass fitting to the inner fender, in place of black rubber hose, so that I could check it occasionally to see if it was clogged.
Now to the fan motor. If yours is okay, then you need not carry out this procedure. But if you blow a fuse every time you turn the fan on then this is your solution. You must remove the heater to do this.
The fan motor is not available separately, and replacing the whole heater is heartbreaking if it’s in good shape. What I did was replace the fan motor armature only, I found a fan of the same size, RPM and voltage. It’s made by Dayton #2M197, 12VDC. My local heating, ventilation and air conditioning contractor ordered it for me for about $12.00. I drilled the rivets out of the housing, removed the armature, and with minimal modification it literally fell into the original Smith’s housing and magnets. Too good to be true. I only discovered this to be accident. Grease the shaft and bearing while you have it apart. You should also change the hoses between the heater and the firewall since people usually don’t change these when changing the other hoses in the engine compartment. Reassemble the unit and test the fan before reinstalling the heater.
I covered the fan intake with a piece of nylon window screen to prevent any debris from entering again. Use a rubber band to hold it in place while putting the heater back in. I also put screen under the grill on the plenum intake so leaves would not clog the drains again.
Now your heating/ventilation/defroster system should be trouble free with a strong Anglo-American fan to keep you warm, and your windscreen clear.
By Steven D’Antonio
Sieve will receive a Moss gift certificate for his contribution.