I was having a good weekend..... now my heater's leaking

[oz3litre]

Just some questions about the resistor pack. One of the resistors has the two posts joined by a piece of solder through the middle of the resistor. This seems to be a sort of fuse that melts if the resistor gets too hot and thereby stops the fan working. Mine keeps blowing that fuse after about a week. It is worse if I run the fan on the slowest speed. I keep a spare one in the glovebox. The questions are:
1. Does that solder need to be silver solder, which I presume has a higher melting point? I have been using ordinary electrical solder.
2. Could my problem be the mesh you mention being clogged? If so, I guess the whole heater box has to come out to get at it or can I squirt it with something?
3. Is my fan motor perhaps dragging and overloading the resistor?
4. Is what I think is a fuse not in fact solder, but just a piece of wire? It certainly appears to be solder based on the two resistor packs I have.
5. Can you get brushes and bearings to rebuild the motors?

[scott.venables]

It's all back together!  I had it done last night but finished too late for a test drive. Unfortunately I missed todays Early Morning Run looking for a loose fuel pump wire. It was on the back on the fuse box but I'd already partially removed the dash. Yes it is nice and toasty, but I've been without a heater for a while so I can't remember exactly how good it was before.

Oz, I'm not sure I'll be able to answer all your questions but I'll give it a go:

The bar between the 2 posts was missing out of mine but I believe it was wire (maybe ni-chrome to resist rust?) It's not a fuse but a low resistance path for the highest fan speed.  The path across the associated blades and through the bar should be 0.5 ohm.  I have used soft solder to attach a piece of stainless welding wire across these posts to the correct resistance.  This path shouldn't see any current with the fan on the slowest speed, it should run through the light wire coil(about 3 ohms resistance).  The intermediate speed uses the heavier coil (about 1.5 ohms)

The resistor board:


Dad mentioned the possible necessity for silver solder after I had finished so I'll have to see how it lasts. I soldered the ends of the other coils onto their posts as well. The mesh I used(aluminium door mesh) was more open than the original so it should stay cool.  The holes in the original mesh were closing up because of rust. I wasn't planning on replacing it but it disintegrated when I knocked it.  You could try compressed air though the resistor hole if it's only leaves etc. but if it's rusty you might blow it to smithereens.

The mesh


My motor had plain bearings on the spindle which I freed up a little by just working some oil in. They weren't as free as I'd like but the oil might continue to works it's way in.  The spindle was tighter than it should have been and no doubt would have been drawing extra current. I think yours would only be better if someone has pulled the dash out in the not so distant past.   I'm not sure if you can get brushes to rebuild the motor. 

The heater core stands up vertically in the front of the box, and the tubes poke through the vertical slot to the right:


Here's a thread you've found on the BB but it may be useful to others:
http://www.alfabb.com/bb/forums/milano-75-1987-1989/170961-heater-fan-resistor-pack-resistance-values.html

Scott

[oz3litre]

Thanks Scott. That is very helpful. The photos are great. I will try wire instead of solder and see if I can check out and clean the mesh if it needs it. The only thing I am wondering is: why does the fan stop working altogether when that wire is broken?

[ARQ164 Shane]

awesome photo. I cheated and used a 2" holewas and replaced the hose clamp on the rubber pipe on the tank in my 75
"worked "

[scott.venables]

Thanks Alphie, I had considered cutting an access hole to get to the bottom hose but luckily I found a better solution.

Oz, all current goes through the bridge you keep replacing, and the motor uses 2 and 3 resistors in series to get the intermediate and low speeds respectively.

Here's a sketch of the terminal layout with resistances and a (very)rough sketch of the mesh piece:


Cheers, Scott

[oz3litre]

Thanks Scott. I will save the info and diagrams. It makes sense now.

[Darryl]

Oz,
a piece of wire is definitely the right answer - not surprised solder melts. You shouldn't need silver solder if you have good metal-to-metal contact between wire and terminals. Copper wire is fine, you don't want nichrome unless you want resistance - which you don't - will just get hot and make the fan run slower. If you get terminals/wire clean and with metal-metal contact the solder is just there to keep it in place. Clean everything - oxide layers don't conduct well (so create heat) and the solder won't bond well (so crack/fail). The 0.5 ohms of that wire link is incidental - 0 ohms is good too (better - less heat).

[oz3litre]

Thanks Darryl. Copper wire will be easier to find and solder. I will aim for the 0 ohms mark. This is one of the many things I love about the internet. It makes problem solving through collaboration with others easier than ever.

[Duk]

How about using a pulse width modulated motor speed controller? Jaycar have 1 that can sink up to 10 amps (20 amps with dual MOSFET's) and heat sinks http://www.jaycar.com.au/productView.asp?ID=KC5225&keywords=motor+speed&form=KEYWORD

[oz3litre]

How about using a pulse width modulated motor speed controller? Jaycar have 1 that can sink up to 10 amps (20 amps with dual MOSFET's) and heat sinks http://www.jaycar.com.au/productView.asp?ID=KC5225&keywords=motor+speed&form=KEYWORD

Thanks Duk. That's a useful thing to know about. Is it controlled by a potentiometer or a switch I wonder? I might check one out for future reference next time I am in Jaycar . It might work on a 164 if the original controller burnt out as they sometimes do. I will stick to the original on the 75 though because it is simple and effective and has the right connections. Once I replace that wire it should be OK.

[oz3litre]

Hi Scott. I fixed my resistor pack with wire, but after a bit of use the fan stopped working and temporarily cut the power to the radio and I could smell plastic burning. Upon inspection tonight I found that the fan is pretty close to being seized solid, so it is obvious that it is drawing heaps of current and melting the insulation on the power wire on the resistor pack. I am going to have to pull the dash and remove the fan assembly and hopefully overhaul it. Can you please describe the procedure for dash and heater fan removal step by step? I believe the dash is held in by five screws. I hope it is not too onerous.

[scott.venables]

I should probably have taken some notes and photos, but here goes.

1. Remove the centre and radio consoles.

1b Remove the lower steering column cowl, unplug all the connectors on the indicator/wiper units, the ignition switch connector, remove the bottom steering column bolt, remove the top column adjuster.  Now the whole column will slide out of the slip joint.  

2. Screws securing the dash:

-2 screws under the aluminium vent at the base of the windscreen
-1 screw on the right hand side of the glove box(inside the glove box lid)
-1 screw on the far left side if the dash behind the glove box in a deep recess above the velcro strip
-1 more on the right hand side of the glove box, at the top of the carpeted opening, just below where the black vinyl dash top meets the grey plastic lower dash

The dash will still sit there with all the screws removed

3.  The instrument cluster I'm quite sure can stay with the dash.  I took it off without realising but if I was doing it again I wouldn't separate them.  Leave the fusebox in the dash, it can be wiggled out forwards through the glovebox opening if you need to work on the back of it but for this it can stay with the dash.  

4. The vents at the extreme ends of the dash are a pain to deal with.  There's 4 main parts:
1.the duct that attaches to the heater box and is screwed to the firewall (this part won't come off with the dash),
2. a 90degreee elbow that sits in the end of the duct,
3. a part that is nearly permanently in the dash, into this is clipped:
4. the vent in the dash, this is what you adjust to direct the airflow

Parts 2 and 3 on mine were glued and clipped together. When I pulled the dash off these parts separated but a few of the clips broke off.  The only way I can see you might get around this is to pull part #4 out of the dash first.  There are 2 short pins that stick out the sides of this, the vent swivels up and down around these pins.  To remove part #4, use a SPAM knife to spread the sides of part #3 enough to release the pins from their holes (one side at a time) and pull #4 out.  Now you should be able to see the join between parts 2 and 3, if you can separate them now that would be great, otherwise you can only hope for the best.

5.  Disconnect the heater tap cable at the heater tap and thread it back through. With extreme caution, remove the heater hose from the heater tap. Remove the 2 screws on either side of the heater/AC control panel.  With these screws removed the panel will flap about.  There is a wiring connector on the bottom of the heater box towards the back that needs disconnecting.

I think now the dash can come out.  From memory all the wiring for the heater/radio/gauge cluster stays with the dash, and the fuse box too.  So now, if you've taken care of all of the above, and if I haven't missed anything, the dash can come out.  You'll need a helper for the other side.  All that is holding the dash in now is 2 pairs of 'fingers' (one on each side) that clip around two short (~1" long) steel rods that run across the car on either side. The dash will need a good tug to spread these 'fingers' over the rods.  Once the dash is off enough, you need to reach in and unplug the wiring connectors that are roughly behind the oil pressure gauge and on the firewall.  Now you need to thread the heater/AC control panel over the plastic piece that runs across the dash under the heater box.  And now I think the dash can come out.  

To get the heater box out, undo the nuts that hold the ducts onto the firewall.  The heater box is held in by 2 screws at the front, once these are out lower it slightly and slide outwards and slightly up to disengage 2 plastic tabs that slide into slots on the firewall.  I can't reccommend what to do about the AC lines as I removed them but I'm pretty sure you'll have to work on the heater box in the car.  There are screws all the way around the horizontal split that need to be undone, also 5 I think spring steel clips along the front, the 2 at either end come off at the top first.  There's sort of 2 top halves if that makes sense, the screws and clips hold the upper top half onto the lower top half and the bottom half,  if you lift this upper top half up gently, there's a single self tapper right in the middle of the box that holds the lower top half onto the bottom half.  You'll need a stubby philips screwdriver to get this one. Now the two top halves will lift off (although they will still be connected to a control cable), and voila! the heater fan is there to be seen.

I think that's about it. Sorry if I've rambled. I'll re-read it tomorrow or the day after with fresh eyes and see how it reads

Cheers, Scott  

Edit:
I forgot to add, there is a control box which I think is for the ARC screwed to the top of the glovebox roof.  There's 3 vertical self tappers along the top edge to unscrew then you can lever it out.  There are quite a few wiring plugs to be disconnected here. 

Also, look at how the wiring for the radio is done. I wired mine up without considering removing the dash.  I had to cut the rear speaker wires when the dash was half out and figure out which cut ends went together after the dash went back in.  If I'd realised sooner I could have put in some crimp on connectors.

[oz3litre]

Thanks Scott, that's very thorough and clear. I think what I'll do is to practise taking the dash out of my wrecked Potenziata first. I have already removed the instrument cluster and most of the console, but I can still gain some experience with all the rest. I am not sure what the heater fan is going to be like when I get it out of that car because it suffered from an engine fire and enough heat got into the back of the dash to partly melt the vents and the back of the speedo. The fan is very tight like the one in my good Potenziata, but it might be repairable with any luck. If it is I can do it up and swap it straight in or, if not, use it to help track down a new motor, if such a thing exists or work out how to fix mine. I am going to be very busy in the coming weeks because I also have to replace the blower motor in our 164. I have a brand new one coming over from the US for that. The 164 is probably easier to do because it comes out from the engine compartment. My brother and I took his out early in the year, so we have some experience there.

Let me know if you remember any other details.

[scott.venables]

Hi Oz.  I've tacked on a few things that came to me today.  A practise removal is a great idea. 

Sounds like a nice design where you can take the 164 fan out through the engine bay! 

I've read the 75 heater fan is different to the US Milano version in case you look for one in the US.  I'm sure you'll be able to free up your spare heater fan.  With the fans removed off the shaft you could in turn soak each bearing in kero/petrol, then blow it out and work some oil in. If you've got a spare to work with then you won't be under pressure when the dash is out of your daily driver. The fans are easily removed and replaced from the shaft if the ones in your wreck are melted

Scott   

[oz3litre]

Hi Oz.  I've tacked on a few things that came to me today.  A practise removal is a great idea. 

Sounds like a nice design where you can take the 164 fan out through the engine bay! 

I've read the 75 heater fan is different to the US Milano version in case you look for one in the US.  I'm sure you'll be able to free up your spare heater fan.  With the fans removed off the shaft you could in turn soak each bearing in kero/petrol, then blow it out and work some oil in. If you've got a spare to work with then you won't be under pressure when the dash is out of your daily driver. The fans are easily removed and replaced from the shaft if the ones in your wreck are melted

Scott   

Thanks again Scott. The 164 fan removal is certainly easier than replacing the stepper motors which do require removal of the dash. You have to take off the wiper motor and loosen the false firewall and air con unit to get the fan out, but you can do it standing up. It takes a fair bit of wrangling and a few swear words to get it out once everything is loose. I wonder if oil will last long term in the bearings. Could something like anti-seize grease be used instead do you think? I would hate to have it fail again later on. Yes I think the Milano heater units are different because the Americans talk about pulling the motor out from the footwell. It is possible that they have the same motor in a different housing but you would need to check the part numbers. They have a lot of trouble with leaves getting into theirs which we don't seem to have.

Just one question: what did you mean by the centre console?