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MG MGA - Heater controls and heater problems

Trying to get my heater up and running and i have a few queries.
The Plastic panel under the dash with the controls in, is it meant to fit into the cut out in the dash bolted hard against the alloy trim , or as in my case it was set back slightly behind the dash and as it was a litle bit higher you struggled to see the writing on the top of the platic trim. If i move it forward i will have to add a couple of washers onto the spacers to lower it down otherwise it looks like it may fracture when its tightened up.What is correct?
Also the heater motor has no wires coming out. Would i be correct in thinking it should have tails soldered on it to conect to the loom. My guess have they been cut off or is there a connector in the motor.
If its a heater motor out job can that be done in situ or is it the whole heater out repair.

Thanks Roy
R Mcknight

Remove three screws from front to remove the air intake pipe and valve assembly. Remove collet nut from fan, and pull fan off the shaft. Remove three screws from back to remove fan motor.

Fan motor should have two pigtail wires (both black) with bullet connectors. These wires pass through a rubber grommet in the side of the motor case. You will need to replace the missing or cut wires. See motor rebuild series starting here: http://mgaguru.com/mgtech/electric/ht_mtr_1.htm

Barney Gaylord

The mounting bolts for the panel are long and should have a couple of spacers at the top to bring the panel down. These should be shown in the parts book - I do not have mine to hand to confirm this.
I can measure the length of mine if you are missing these.
Peter.
P. Tilbury

Thanks Barney and hi Peter , Yes i have the correct spacers and i have the originals and repro's they are all the same size. So dont know why i have to add extra washers to make it fit snuggly.

2 more questions.

Should the flap at the bottom of the heater to warm your toes have a foam gasket or is it just metal to metal?

And if i have the heater motor out is it worthwhile fitting the uprated fan blades to the heater as available from Moss and MGOC. And any experiance of uprated Matrix's that are available. I dont mind being cold its defrosting the windscreen thats being a pain.
R Mcknight

Oh yeah, the first question. There are two different length tube spacers and long screws to attach the heater control and panel under the dash. See fasteners here: http://mgaguru.com/mgtech/heater/hr104.htm

In the SPL the fasteners are shown as part of the control assembly, not listed as separate part numbers.
Barney Gaylord

The flap on the bottom of the heater which directs the air flow does not as far as I'm aware have any seal on it.

John
J Bray

I put a thin layer of felt on mine, seals very nicely and was very easy to do. I just glued it into the flap so it sits in the flanged edge. The heater is so asthmatic, it needs all the help it can get for demisting the windscreen
dominic clancy

No body has said so yet, although Dominic got close! The heaters are practically useless! Compared with other cars (my Australian-built Holden being a case in point) MGA heaters are not in the same league. I dare say that there will be howls of derision but let me say that I have two restored MGA's with heaters (coupe and roadster) and neither of them are much good. OK for clearing the windscreen on wet nights. Another thing is that no air comes in unless I have the fan going (even though I have the trunking just behind the grille).
Barry Bahnisch

I agree the heater on my car is useless. So i assume i can improve it by (1) Fitting a 7 psi rad cap (4psi fitted) (2) Fitting a winter stat (3) remove engine fan and fit electric unit.

Now MGOC list a higher output fan motor and squirrel cage fan blade, and also a higher output heater matrix, anybody used these items?

And does anybody have a working heater that chucks out lots of heat?
R Mcknight

What temperature does the car run at?
Does it heat up quickly?
Do you have an oil cooler?
Do you have a radiator blind?

Mick
M F Anderson

Roy

Just doing my usual thinking out of the box. Is the heater valve on the block functional? But probably more important, is the waterway hole behind the valve clear? During my engine rebuild a while back I found that hole almost blocked off. It is only a small hole when fully clear so any build-up of crud will soon restrict hot water flow.

My heater is standard and produces decent hot air.

Steve
Steve Gyles

Roy, don't confuse the heater performance with your engine running temperature. If you have a working thermostat then the coolant temperature should not be the main problem.

First thing to check is the temperature of the heater matrix (try to gauge from the rubber pipes) The heater tap and the outlet hole in the head can be easily blocked, restricting flow. also the matrix itself can become blocked over the years both internally and externally restricting coolant and air flow respectively.

May be necessary (or worthwhile anyway) to remove the heater box and check. At least you can do a nice cosmetic job in the back of the engine bay!

With everything working as it should and the fan turned on it will not blast hot air like other cars, but you will be able to feel a flow of warm air when you put your hand near the outlet or defroster.

My money would be on the heater tap!
N McGurk

I Drive my Car a Lot in Winter too, and the heater works just fine at keeping the open passenger compartment warm. But for demisting the screen the arrangement is, as Barry says, useless. A felt seal seems to help a bit, but I freely admit it could all be in the mind.
dominic clancy

If you are looking for peak heater performance (if you can call it that) do not rely on the thermostat.
The thermostat opens at 70 C (158 F).
You should try and have the engine running at least 82 C (180 F).
Even 88 C (190 F) would be preferable.
That is why the factory had a radiator blind as an option.

Mick
M F Anderson

Well i stripped out the heater to check the motor . On stripping down I found the squirrel fan is marked Smiths and its yellow plastic and its a push fit onto the shaft. On removing the motor with no wires I found that there are no pigtails but 2 slots for spade connectors. The motor has no marking so probably not Smiths. I fitted the wires and found that the motor will run either way by transposing the wires but the fan should run clockwise when facing it. I wish i had looked closer as i could have fitted the wires without stripping everything down.
So info for Barney there are Heater motors that will run either direction.
Heater works a treat so i can only assume that the plastic fan is an uprated part.

Roy
R Mcknight

Ray,

I thought the MGA had a metal fan, so I presume you may have an MGB fan and motor fitted although from recollection the 'B' fan was white plastic.

I have a spare "A' motor and fan if you would like to try it for comparison.

My car has the MGB fan fitted in the MGA housing..

Regards...John
J Bray

Roy,

I thought the MGA had a metal bladed heater fan, so I presume you may have an MGB fan and motor fitted although from recollection the 'B' fan was white plastic.

I have a spare "A' motor and fan if you would like to try it for comparison.

My car has the MGB fan fitted in the MGA housing..

Regards...John
J Bray

Originally MGA fan is metal. Original MGA motor has pigtail wires, both black with bullet connectors. It is series wound and only runs one direction, switching wires makes no difference. Later model MGB motors will change direction of rotation if you switch the wires.

In August 1998 I needed a heater motor. There are multiple part numbers for different model cars. Most of the parts suppliers did not have one for MGA. Victoria British had one part number for multiple applications, and I bought one. I returned it when it turned out to be the wrong part for MGA. It was an inch shorter than the original motor and would change direction when the wires were switched.

I bought a used motor the didn't work. I bought another used motor that ran the wrong direction (probably a Twin Cam or early MGB part). I switched wires on the field coils inside to run the correct direction. A few weeks later it burned out the armature (no idea why). My ultimate solution was to rewind the armature on my original motor, and it is still working 120,000 miles later.
Barney Gaylord

Hi John , thanks for the offer but everything is working fine now . Dont know what the plastic fan is from but it works well, The motor that was fitted was new just had no wires. It blows treat now .

Roy
R Mcknight

Roy,
the yellow fan is most certainly from an MGB, possible aftermarket, they deliver much more air than the orignal MGA fans.
Siggi
Siggi

Is it difficult to fit yellow MGB fan ?
H L Davy

Re heater performance: I found that having a good water valve on the block makes a difference. Many of the replacement valves do not open or close all the way (either by hand or by use of the heater controls) and some will only fully open or close by hand. So try to install your control wire to maximize the effectiveness of the valve control. Depending on the time of year, I still give the valve control a shove by hand from time to time to get either full heat or full fresh air.

M.D.
'57 Coupe
M. D.

Just a word of caution, while cleaning the heater controls today ready for installation into the car.

I tried cleaning the black blower knob by putting it into a beaker of hot water. when I removed it a few minutes later all of the colour had gone and its now a light grey rather than a dark brown colour.

John
J Bray

I am taking my heater out, so I ordered an MGB fan last night - $16 - to try out.

JIM

AJ Mail

John

Sounds like the previous owner used a bit of Kiwi black shoe polish!

Steve
Steve Gyles

Steve,

An old RAF trick I believe

John
J Bray

This thread was discussed between 15/12/2012 and 08/01/2013

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