Aircon poor on tickover

[BRMFUN]

Help please, my aircon is poor on tickover, so i tried the demist switch and the fan does not kick in. This may also why the car briefly overheated when stuck in Traffic a couple of days ago!
Anyway its a Mk2 o4 plate, and it looks like no resistor is fitted, is this normal on a Mk2, 1.8 T?
And how do i fix the fan now
Thanks in advance.

[T-Cut]

An 04 Mk2 1.8T would usually have the later resistor controlled fan, but there's no guarantee. The only way to be sure is to remove the front bumper and examine the motor wiring. A resistor type motor has two wires entering the case. The older system uses a three wire motor. If it's two wires, the resistor could be hidden out of sight. It should be mounted on the fan shield bracket.

Three wire motors might be successfully rebrushed. If not, a replacement resistor type system or an after-market fan kit is the usual fix. If you find a resistor, you need the gold upgrade type from forum traders, ebay, electronics outlets, etc.

TC

[KeithA]

What do you mean by 'poor'?

Sent from my LG-D855 using Tapatalk

[BRMFUN]

What do you mean by 'poor'?

Sent from my LG-D855 using Tapatalk

Pretty none existant really :p:

Bumper off I think is the next stage, I have to get BRM 201 on the road first, which should be this week !

[SCP440]

Might be worth getting to see if it has enough gas first, the reason the fan kicks in is because the compressor is working hard. No gas or not enough and it wont kick in

[BRMFUN]

Might be worth getting to see if it has enough gas first, the reason the fan kicks in is because the compressor is working hard. No gas or not enough and it wont kick in

That's a good point, but it did overheat a couple of days ago which sort of pointed to fan???

[T-Cut]

You've done the Demist test, try the trinary test: http://www.the75andztclub.co.uk/forum/showthread.php?t=35567&highlight=jules+fan

The Demist test is the default test for slow speed and is valid even with a gasless aircon system.

The slow speed fan is automatically tripped on with the aircon because it's required to cool the condenser. No slow speed = poor aircon performance. It's OK on the move (ram effect cooling) but overheats when stationary (trips on the high speed emergency cooling fan, which pulses on/off).

TC

[BRMFUN]

You've done the Demist test, try the trinary test: http://www.the75andztclub.co.uk/forum/showthread.php?t=35567&highlight=jules+fan

The Demist test is the default test for slow speed and is valid even with a gasless aircon system.

The slow speed fan is automatically tripped on with the aircon because it's required to cool the condenser. No slow speed = poor aircon performance. It's OK on the move (ram effect cooling) but overheats when stationary (trips on the high speed emergency cooling fan, which pulses on/off).

TC

Sorry late reply!! So what will the above test prove? I now know my low speed fan is not working from the demist test, or is there something else to know? My other issue is it looks like a two speed attempt on a 04 plate mk2, is that normal? Ie no resistor.

[SD1too]

I now know my low speed fan is not working from the demist test, or is there something else to know?
Not really.
... it looks like a two speed attempt on a 04 plate mk2, is that normal? i.e. no resistor.
I don't know what you mean by "attempt" Pat. :shrug: All 1.8 litre cars have two speed fans. The original circuit didn't use a resistor but the later design did. We've discovered that the earlier circuit can crop up on later cars. As T-Cut said in post number 2, there's no guarantee which it wil be until you remove the bumper. Haver you done that yet?

Simon

[BRMFUN]

Not really.

I don't know what you mean by "attempt" Pat. :shrug: All 1.8 litre cars have two speed fans. The original circuit didn't use a resistor but the later design did. We've discovered that the earlier circuit can crop up on later cars. As T-Cut said in post number 2, there's no guarantee which it wil be until you remove the bumper. Haver you done that yet?

Simon



attempt.... Typo :duh: Thanks Simon, it's now got a small coolant leak from the elbow gasket so, repairing that and the bumper will be off when that's done. I will put some pics up.

[BRMFUN]

Ok bumper off, as well as all the other Millions of bolts etc, now remember why I got rid of my ZTT :) This is what I have...

http://i1115.photobucket.com/albums/k556/BRMfun/Mobile%20Uploads/image_zpskucbnrvr.jpeg (http://s1115.photobucket.com/user/BRMfun/media/Mobile%20Uploads/image_zpskucbnrvr.jpeg.html)

http://i1115.photobucket.com/albums/k556/BRMfun/Mobile%20Uploads/image_zps6nffmhbr.jpeg (http://s1115.photobucket.com/user/BRMfun/media/Mobile%20Uploads/image_zps6nffmhbr.jpeg.html)

New parts coming from Jules!!

[SD1too]

You have the original 2 speed design there Pat. The reason for the loss of slow speed will be a worn out motor brush. Replacements are available very cheaply if you fancy opening the motor casing and doing a bit of soldering.

Simon

[BRMFUN]

Well so far I have replaced everything, fan, relay, resistor etc and nothing!! If I bridge the relays the fan works! Continuity seems good on all the wires...plugs etc earth cleaned...

I am about to lose it big time....

[SD1too]

Well so far I have replaced ... resistor ...
Resistor Pat? :confused:

In your earlier post you showed us three wires entering the motor casing:

http://i1115.photobucket.com/albums/k556/BRMfun/Mobile%20Uploads/image_zpskucbnrvr.jpeg

Fans with a resistor in the circuit need two wires, not three.

But you've also bought "new parts" from Jules. Have you fitted his Revotec aftermarket system?

Simon

[BRMFUN]

Apologies yes new system fitted, which is a good upgrade! I fear talking to Jules T4 is my next step which is rather annoying!!! However I need to find a local T4 person, who is nearest to Worcester?

[SD1too]

Well so far I have replaced everything ... and nothing!! If I bridge the relays the fan works!
Was the engine running at the time of your tests?

Simon

[BRMFUN]

Was the engine running at the time of your tests?

Simon

Yeah Simon it was, it's pointed to ECU but I can't believe it's that really :)

[SD1too]

... it's pointed to ECU but I can't believe it's that really :)
Neither can I. ;)

When fitting the Revotec fan, have you retained the original MGR control box and relays?

Which relay terminals did you bridge: the thin wires to the coil or the thick wires to the contacts?

Double check that you've wired the Revotec properly. I seem to remember that the instructions aren't the clearest in the world. :o

Simon

[BRMFUN]

Yes retained the control box but fitted new relays, which I have double checked are wired properly. I bridge the two black wires on the large relay and the purple and black on the other.

I will triple check the wiring :)

[BRMFUN]

3 black wires coming out so has to be colour code 4 beg switching.

http://i1115.photobucket.com/albums/k556/BRMfun/Mobile%20Uploads/image_zps8qsohew4.jpeg (http://s1115.photobucket.com/user/BRMfun/media/Mobile%20Uploads/image_zps8qsohew4.jpeg.html)

http://i1115.photobucket.com/albums/k556/BRMfun/Mobile%20Uploads/image_zpsyxe8inbj.jpeg (http://s1115.photobucket.com/user/BRMfun/media/Mobile%20Uploads/image_zpsyxe8inbj.jpeg.html)


I have checked and the only ones I can do wrong are mixing up the two black wires??

[BRMFUN]

I am going to go over the whole thing again, because as I read it I dong feel sure!!!

[BRMFUN]

It appears to be wired correct. Confirmed I think by the fact both fast and low speed fans run when the wires are bridged hence no signal to the relay??

[SD1too]

Pat,

You appear to be following the correct set of instructions but they incorrectly mention a gold resistor which the 3 wire motor circuit doesn't have! :rolleyes:

If I were you I would refit the original relays. There will be nothing wrong with them and we know that they're the correct spec. Then try the demist test again and let me know the result.

Simon

[BRMFUN]

The gold resistor is supplied with the new Revtec, will try old relays later, thanks

[SD1too]

The gold resistor is supplied with the new Revtec ...
I'd like to see how you wired the Revotec to your existing 3 motor wires Pat. I suspect that we might find the reason there. Can you supply a diagram?

Simon

[BRMFUN]

I'd like to see how you wired the Revotec to your existing 3 motor wires Pat. I suspect that we might find the reason there. Can you supply a diagram?

Simon


Old relays made no difference. I will take some pics when I get in and draw on them... explaining what went where. Thanks

[BRMFUN]

It is wired up correctly 100% had it checked by auto electrician all wires have continuity, as said bridge the wires and it works fine. With the demist on put power to the yellow wire on the low speed relay and on it comes!

I can't see any other option than another £50 at least down the pan doing T4 test....

[SD1too]

OK Pat; that's useful information, thanks.

First of all, the +12v supply to the yellow wire comes via fuse 4 in the engine compartment fusebox. Have you checked that it hasn't blown?

If it's intact, trace the yellow wire back from the fan control box to one of the two large black connectors at the car's harness. Check that for security and clean connections. If you invest £5 in a multimeter from e-bay, you can measure the presence, or not, of +12v and find where the problem lies.

T4 won't help you. It will try to activate the fan's slow speed and fail. It will then tell you that you have a fan fault, which you already know!

Simon

[BRMFUN]

SD1too..... Can I have your babies!!! Brilliant job done, fuse replaced fan working! The diagram just shows a book, I never thought for one min that would be another fuse! I can't thank you enough! I owe you a good drink!!! Pat

[SD1too]

I've just had a horrible thought Pat. It couldn't have been the fuse all along ... could it? :o

Did you ever do the trinary switch test?

Simon

[BRMFUN]

Simon, I thought the same but I tested the old fan and it's dead! So perhaps it blew it when it seized up?

Being even more positive the fan itself is a good upgrade from the original anyway :)

[BRMFUN]

All sorted now thanks everyone for their help!