Aircon/Fan stops for a sec on full

[Roadrunner]

Hi,

was driving along yesterday and had the aircon on. It seems that if the fan is on full (4) every now and then the fan stops for a second and starts again. It might not do it for an hour or so or it might do it 3 times in a row.
It only seems to be when the fan is on full.

Also this aircon must must suck some horses from my engine. Every time it kicks in you can feel it's happening. It's a Disco 300tdi

Matt

[ladas]

I am not sure what vehicle you have - but this could be caused by the pressure switch for the gas.

It could be tripping on low or high pressures, low pressure usually indicates a gas shortage, high pressures is normally (if the gas charge is correct) by a blockage in the pipework/filter drier, bad air flow over the condenser, or faulty condenser fans.

However as mentioned your vehicle may not be wired that way (where the pressure switch affects the internal fan) so are many are not.

And yes a/c compressors do pull a few horses from the engine - especially when the head pressure is up above normal (250 psig +)

Check the condenser fans first to see if they/it is running, then if you have a test meter check the pressure switch.

If you let me know what vehicle I'll have a look at the wiring diagram (if I have it).

Ladas

[Roadrunner]

96/Disco/tdi

[ladas]

Okay on the Disco TDi the internal fan is not interupted by the pressure switch. So we can count that out.

So it looks more like a loose connection, faulty switch, faulty blower relay and/or bad earth on the relay or poor earth at the motor, and as it is only on full speed we can eliminate the fan speed resistor pack - (full speed bypasses the resistor pack)

It could be a loose fuse or dirty contacts on the earth.

I have attached a copy of the wiring for that part - it's pretty basic so you shouldn't have to do much to trace the fault

[Roadrunner]

Thanks for that. Looks like I have to stick my head near the fuse box and follow some cable. Sounds like fun :p

Matt

[altech]

Mine does the same thing ,only on 4 setting , I found this only happens when engine is still cold and need cold air on myself quickly :) , but I'm use to having it on 3 , with no problems , 4 is just a lot of air . cheers alex :cool:

[justinc]

Hi Matt,

Just been through this with another one. Could be 1) fan switches on these can 'melt' slightly
2) fan speed controller can have seniors moments/ connector plug issues, or 3) there is a loom that can rub through up on the LH side behind glovebox, under the Airbag support bracket. This was the problem with the last one, the wiring had 'welded' the dash bracket periodically for quite some time, causing intermittent shorts and open circuits to the heater blower fan. Not one fuse blew!!!!! Give me a call, and I'll tell you how to get up under the dash to check it.
Incidentally, that vehicle had some similar use to yours.....

How did the MIG perform?

JC

[Rovernaut]

I had a similar problem with mine.
I had a relay that was not holding the contacts open under load thus intermitantly cutting off the A/C.
The relay is located under the drivers side foot panel.
Swapped it with a working one and it fixed it. They are just a stand Hella relay. you need to reach up above the 1st rack of relays that you can easily see

Later I developed another problem with the A/C on speed 4.
I just tap the switch knob and instantly comes back on.
These switches are known to play up and I believe if you can remove it and give it's sliding contact points a light emery it might fix it.

[amshaw]

[quote=Rovernaut]I had a similar problem with mine.
I had a relay that was not holding the contacts open under load thus intermitantly cutting off the A/C.
The relay is located under the drivers side foot panel.
Swapped it with a working one and it fixed it. They are just a stand Hella relay. you need to reach up above the 1st rack of relays that you can easily see

I had a look and ther e are 3 relays low down....2 yellow and 1 green......above that there is another yeloow one all by its self about 100mm or so, is that the one?

[101RRS]

Mine did it the whole 11 years I had by D1 update - did it from new. I assumed it was normal and also assumed it was to let the A/c to defrost.

Gazzz

[Rovernaut]

[quote=Rovernaut]I had a similar problem with mine.
I had a relay that was not holding the contacts open under load thus intermitantly cutting off the A/C.
The relay is located under the drivers side foot panel.
Swapped it with a working one and it fixed it. They are just a stand Hella relay. you need to reach up above the 1st rack of relays that you can easily see

I had a look and ther e are 3 relays low down....2 yellow and 1 green......above that there is another yeloow one all by its self about 100mm or so, is that the one? Mines a V8 so I may have more than a TDI.
I can't recall what colour it was. It operates the Compressor clutch. When mine was playing up it kept disconnecting the compressor clutch
Just turn on your aircon and pull them one by one. When it stops you'll have the right one.
Do You have A RAVE CD, I found on mine it had photos

Ok, heres a pic of the location of the compressor clutch raly for a tdi
https://www.aulro.com/afvb/images/imported/2007/01/240.jpg

and this is for V8s including A/C logic relay and copmressor relay.' similar for others it says.
https://www.aulro.com/afvb/images/imported/2007/01/241.jpg
https://www.aulro.com/afvb/images/imported/2007/01/242.jpg

[amshaw]

Thanks bud....I took a punt and pulled the higher one by it self.....and it seems to have fixed the prob.....thanks very much I didnt even know there where relays behind there:oops2:

While you have your RAVE in the PC, do you know where the relay is for the condencer fans?:confused:

Or are they run off the relay I just replaced?

I think I might as well buy about 15 relays and replace the lot and be done with it:eek: .....I cant get over how many there are, so hence having trouble find the one's I want.

[Roadrunner]

So some of you think it's not a bug it's a feature :p
Need to have a look tomorrow.

JC: welding was ok. Just thin around that old plate. I've welded new ones on top after I filled all the old holes.
Engine stopped again for a few seconds from my way back from Launceston. Foot off the throttle and back on and she was running fine. Does that thing log error codes ??

Matt

[Rovernaut]

Thanks bud....I took a punt and pulled the higher one by it self.....and it seems to have fixed the prob.....thanks very much I didnt even know there where relays behind there:oops2:

While you have your RAVE in the PC, do you know where the relay is for the condencer fans?:confused:

Or are they run off the relay I just replaced?

I think I might as well buy about 15 relays and replace the lot and be done with it:eek: .....I cant get over how many there are, so hence having trouble find the one's I want.
Mate your going to have to go to the passenger side for that one.
By the way there are lots of relays in the passenger side kick board as well.

Here the pic your require.
Happy hunting.
Cheers, Rovernaut
https://www.aulro.com/afvb/images/imported/2007/01/237.jpg

[Roadrunner]

I found one on the drivers side that tick's when you press the aircon button. I opened it and the contacts are pretty burned. I opened some of the others and they look like new. I will replace the burned one and also have a look in the passenger side.

Matt

[Rovernaut]

I found one on the drivers side that tick's when you press the aircon button. I opened it and the contacts are pretty burned. I opened some of the others and they look like new. I will replace the burned one and also have a look in the passenger side.

Matt
That's How I originally found the solution, had my head down there and heard the buzzing/clicking of the relay.
In the darkness I could see the arcing of the contacts through the relay casing.