Visit our Twitter feed for more great content
AHExp

The 100 Forum

Heater motor or switch problem

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

Michael Oritt Avatar
LUSBY, MD, USA   USA
The fan motor in my heater worked nicely all summer but naturally chose to crap out once cooler weather arrived a few days ago and I'd like some advice from those 100 drivers who have previously removed/remounted their heaters.

I have verified that power is getting to the heater lead from the fusebox I installed in the engine compartment, and the green wire disappears into and through the firewall, apparently intact Without disassembling the heater I cannot access the rheostat switch to trace whether it or the motor is the issue and before I pop off the three spring clips that seem to hold the heater faceplate to the rear plate I would like to know that doing so will allow me to get to the heater's innards.

Also I would appreciate learning whether reassembly is the reverse of disassembly as those clips, esp. the one at the 12:00 o'clock position, do not look like they will be easy to get back into place with the heater mounted to the firewall, which leads me to my last question: How is the heater unit fixed to and removed from the car should I need to access the fan motor? Aside from one screw going through an ell-bracket at the top of the faceplate I see no other fasteners projecting through the firewall.

Thanks in advance.



Best--Michael Oritt
1954 Austin-Healey 100 (street)
1958 Elva Courier (track) FOR SALE
1959 Elva MK IV sports racer (track)
1961 Ginetta G4 (track)

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Koudekerke, Zeeland, Netherlands   NLD
Michael,

The heater itselve is installed with 3 nuts, 2 accessible from the drivers side and one nut from the engine compartment.

What i remeber it is possible to remove the demister Y piece and the the 3 clips and you will have access to the rheostat switch and fan motor without removing the heater unit

filospinato Avatar
filospinato Jake Voelckers
Manassas, VA, USA   USA
I can post pics of a disassembled one if it helps, I'm about ready to put it back together.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Michael Oritt Avatar
LUSBY, MD, USA   USA
Jake--

I believe I have enough info from previous replies but thanks for the offer.



Best--Michael Oritt
1954 Austin-Healey 100 (street)
1958 Elva Courier (track) FOR SALE
1959 Elva MK IV sports racer (track)
1961 Ginetta G4 (track)

Guido36 Avatar
Guido36 Guy C
Ventura, CA, USA   USA
1953 Austin-Healey 100 "Aggie"
Jake - I would appreciate it if you would post photos. I am gathering parts to make a heater as mine does not have one. Thanks

Guy

filospinato Avatar
filospinato Jake Voelckers
Manassas, VA, USA   USA
Hi Guy,
I'll take so me tonight and post a link.
Jake

Michael Oritt Avatar
LUSBY, MD, USA   USA
About an hour ago I popped the spring clips off of the heater face-plate which gave me access to the back of the rheostat switch. I first verified that there was power to the switch and then jumped across the two posts with a screwdriver. The heater motor came on full blast, telling me that the problem was in the switch, which had felt a bit odd when I initially encountered the problem a few days ago as the "detent-like feel" when turning the fan on was missing. Though I assumed I had identified the problem as being in the switch I nevertheless turned the control knob just to see how it felt and--wonder of wonders--the fan motor immediately came on. What's more it responded perfectly to the rheostat, going from full blast to low just as it always had.


I am 100% certain that I had the ignition switch on and the heater power lead connected with an intact fuse and I can only say that this is a typical Healey deal, and now that the car has my attention I am sure that should I simply close the heater up the switch will probably act up at some point in the future. I'm going to investigate whether I can source a replacement switch, either Lucas or not. I'll also take the opportunity to repaint the front plate in black crackle and I am going to close off the top opening that supplies heated air to the two vents in back of the windshield, which seems like a waste of hot air.

Thanks all for your patience and advise and I hope this gives some of you who have experienced similar situations a laugh.

Best--Michael Oritt



Best--Michael Oritt
1954 Austin-Healey 100 (street)
1958 Elva Courier (track) FOR SALE
1959 Elva MK IV sports racer (track)
1961 Ginetta G4 (track)

filospinato Avatar
filospinato Jake Voelckers
Manassas, VA, USA   USA
Pictures of a complete heater that I took apart, as well as another one ready to go back together.

Healey 100 Heater

Guido36 Avatar
Guido36 Guy C
Ventura, CA, USA   USA
1953 Austin-Healey 100 "Aggie"
Jake - thank you - that is perfect and a very useful reference.

Guy

Michael Oritt Avatar
LUSBY, MD, USA   USA
Jake--

Thank you and I'll agree those pics are very helpful.

Looking at the next to last pic in the series it appears as though the motor is grounded to the car via a mounting bolt though it looks as though there is another wire from the stud going to, I assume, a separate ground. If this is correct do you know where that ground contact is made?

Best--Michael Oritt



Best--Michael Oritt
1954 Austin-Healey 100 (street)
1958 Elva Courier (track) FOR SALE
1959 Elva MK IV sports racer (track)
1961 Ginetta G4 (track)

filospinato Avatar
filospinato Jake Voelckers
Manassas, VA, USA   USA
Hi Michael,
I see the question with that picture. The wire is in the background from the motor harness, which is specific to the Healey. The motor isn't grounded through the chassis, it has its own wire coming out of the side. I'll take a clearer pic of the harness setup if it helps. That one was meant to show the hex stud mounting arrangement.
Jake

Michael Oritt Avatar
LUSBY, MD, USA   USA
I am trying to avoid removing the heater body and because a less-than-perfect ground is a possible cause for the intermittent problem I would like to establish a new one. I have not been able to locate the ground wire out of the rear of the heater and knowing where it terminates would help me to find the present lead.



Best--Michael Oritt
1954 Austin-Healey 100 (street)
1958 Elva Courier (track) FOR SALE
1959 Elva MK IV sports racer (track)
1961 Ginetta G4 (track)

filospinato Avatar
filospinato Jake Voelckers
Manassas, VA, USA   USA
There are two wires that exit a grommet on the side of the aluminum mounting bracket toward the firewall, one of them has a bullet connector on it, the other goes into the front cover with a ring terminal and goes to the switch. The other side of the switch has a wire with a ring terminal that exits the front cover and meets back up with the first bullet, also a bullet. Rheostat switch in series with the motor, ground and power wires. They should plug into your harness. Do you only have one wire exiting? That might be the issue, as the three motor mounting lugs on the motor have rubber vibe isolators that go between them and the hex studs. If someone grounded the motor to one of the studs, maybe the problem is where that stud meets the chassis?

Michael Oritt Avatar
LUSBY, MD, USA   USA
Jake/All--

I had to make an executive decision this morning: I chose to pass on removing the unit and opted to simply remount the faceplate after rewiring the switch and (hopefully) cleaning up its innards with Electra-Clean. Unless a future failure requires it I am just not up for removing the motor in order to get to the bullet connectors.

I know I am taking the easy way out but as I said in an earlier post when the problem first arose it felt like the switch was not operating properly, the on/off detent not feeling as positive as it had previously. Perhaps some small bit of debris was in the way, perhaps I am engaging in wishful thinking. The switch now seems to feel correct and the motor run perfectly. If nothing else the unit now looks much nicer with its new black wrinkle finish.

Maybe I will get lucky or maybe, as Michael Salter wryly predicted, it will fail again as soon as I pull out of the garage. We'll see, but thanks to all for the patience and advice.



Best--Michael Oritt
1954 Austin-Healey 100 (street)
1958 Elva Courier (track) FOR SALE
1959 Elva MK IV sports racer (track)
1961 Ginetta G4 (track)

DTDuck Avatar
DTDuck Dan Marshall
Redwood City, CA, USA   USA
In reply to # 206322 by Michael Oritt Jake/All--

I had to make an executive decision this morning: I chose to pass on removing the unit and opted to simply remount the faceplate after rewiring the switch and (hopefully) cleaning up its innards with Electra-Clean. Unless a future failure requires it I am just not up for removing the motor in order to get to the bullet connectors.

I know I am taking the easy way out but as I said in an earlier post when the problem first arose it felt like the switch was not operating properly, the on/off detent not feeling as positive as it had previously. Perhaps some small bit of debris was in the way, perhaps I am engaging in wishful thinking. The switch now seems to feel correct and the motor run perfectly. If nothing else the unit now looks much nicer with its new black wrinkle finish.

Maybe I will get lucky or maybe, as Michael Salter wryly predicted, it will fail again as soon as I pull out of the garage. We'll see, but thanks to all for the patience and advice.
If you do end up needing a replacement rheostst, they can be had from most of the usual suspects:
https://www.ahspares.co.uk/austin-healey/big-healey/Electrical-Switches/HEATER-RHEOSTAT-SWITCH-LUCAS.aspx
https://mossmotors.com/switch-rheostat-replacement?assoc=5741

Cheers,
Dan M.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions




Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster





Join The Club

Sign in to ask questions, share photos, and access all website features

Your Cars

1960 Austin Healey Bugeye Sprite

Text Size

Larger Smaller
Reset Save

Sponsor Links