Intermittent Blower (Evaporator)

2002 TF with Aircon.
I have never tried to use the aircon but now the blower sometimes stops.
It starts again after tapping the evaporator behind the glove box.

I'm trying to determine what to do - there must be a faulty connection inside the evaporator - but how can I fix or bypass the unit.
IInfo on aircon is sparce.

Any ideas - Thanks

The community part of the site had circuits of both f & tf which include diagrams showing air con’. There is also the full service manual available to download. I have spent many happy hours trawling through both but as I haven’t had air con’ in the tf or f I have overlooked those pages.
These are good starting points.
I suspect the Australian cars, which were highly spec’t, would, by necessity, have air con’.
If that is the case Cobber is the chap to volunteer information.
M

It’s almost certainly going to be the blower speed resistor board on the side of the heater box. After years of sitting in the airflow to keep it cool the resistance wires rust and get thin and then break. They aren’t expensive and if you don’t have a/c are fairly easy to replace. However, with a/c the evaporator blocks access and must be removed! Before I installed my a/c this last summer I replaced my resistor pack with an upgraded type from Rimmer. It lasted about a month and forced me to pull the evap assembly after discharging the freon and recharging after the replacement. I was not a happy camper at that point. The second new one has been working great since then.
Not a fun job. Be very careful with the two pipes going forever through the firewall as the evap swings a bit when coming out and they can catch the edge of the hole.

Thanks for replies..
I have replaced the resistance wires on a previous TF. However that failed with just 2 of the four speeds inoperative.
In the current problem all speeds work at the same time but then all will cease - it's intermittent !

Does the evaporator have an electrical link to the blower which may be causing my issue - or are we quite confident that the speed resistor board is the likely culprit?

Thanks again

Yeah most likely the fan motor resistors or a shiity connection, not that I’ve ever had to do anything to the AC than regas it.
To do I pumped the useless R134a refrigerant gas out, replaced the dryer, vacuumed the system down for @ an hour and replaced the gas with a charge of Hychill 30…… a much more efficient refrigerant gas than the R134a rubbish.
A much smaller amount of gas is required and at a lower pressure, is needed with Hychill 30. The AC was very marginal with R134a….. to be almost useless……now it blows colder than a politician’s promise!

BTW if you have AC you should give it a run for @ 10 minutes once a month to keep it lubed.
Even in your bloody awful climate it cam be useful as a very effective way to demist the windscreen as the air is dry.

Cobber, I may try and fit air con into my MGB and will attempt to cobble something together myself. I have read quite a bit about the R290 and R600a gasses both straight and mixed and 99% of the time I think they are the very best option then the 1% kicks in (the flammability issue) and the doubt resurfaces. Is Hychill odourless so you can smell it if there is a leak or am I just being paranoid? I am cynical enough to believe that the refrigeration gas manufacturers don't want their milk cow being killed of and replacing with a harmless to the ozone mix of natural gasses, their only weapon being the flammability issue.
It seems that Hychill is an Australian only mix, we only have R290 and R600a, is it possible to mix yourself by part filling with one then topping up with the other?

The intermittent operation of the blower is usually caused by the broken resistor wires making contact when cold and then flexing when they get hot causing the blower to stop.

Yeah the risk is pretty minimal as there is only a very small amount of gas in the system with Hychill in the event of a leak due to a failed seal it will most likely leak out very slowly at a rate as to be unlikely to pose a problem.
A quick loss of gas due to a crash or some such, will be very cold and unlikely to ignite before it’s exhausted and dissipated.
You have a greater fire risk from the petrol.

I really couldn’t say much about R290 or R600a as I’ve had bugger all to do with them.

I gather you in the UK, as far as I can tell the are distributors in both France and Spain, but not the UK.
It’s even available from Amazon here, dunno about about elsewhere.

It’s much cheaper than R134a so that’s a tick in the + column, as is the fact that due to lower pressures required there is much less load on the compressor which will pay dividends in power savings, longevity, economy and less likely hood of leaks
You do need the usual AC equipment to use it, such as valves, gauges, hoses, vacuum pump etc.

Cobber, unless I have got it wrong Hychill is a 50-50 mix of R290 (Propane) and R600a (Isobutane). In Europe there are several companies selling Propane (R290) as a drop in refill to top up R134a systems without draining or evacuating the existing gas. However I am not sure if it legally allowed to use more than a partial charge. The refrigeration gas manufacturers are pushing back at allowing these more efficient gasses because the freons are so profitable for them. On the other hand the lawmakers are allowing domestic fridges and freezers to be fully charged with R290 or R600a due to the improved efficiency. Industrial refrigeration can use these gasses because the whole system is mounted externally to the building and there is no fire risk.

Yeah I believe Hychill 30 is basically a cocktail of 600a and 290, but I don’t know the ratio, having used it in several vehicles it shits all over 134a, which is getting phased out here anyway , in its place will be F1234yf, which also a flammable gas
Most household fridges sold here now are running R600a…….no one seems to be having their houses engulfed in flames due to their fridge.

Thanks all,
I can’t get it to fail now that I’ve tied up the wires to the resistor block (they were quite tight).
So I’ll see if further fails occur and if so change the resistors.
Thanks again

There is nothing in the evaporator unit that will affect the operation of the fan/blower.

Instead of degassing the a/c system, you might be able to access the fan speed resistor pack from the interior air intake. I've seen some pictures that show when the air intake/snorkel is removed that access to the fan speed resistor pack might be possible. If not, I have seen pictures where someone (on this this forum I believe), relocated the resistor pack to the evaporator.