Z3 Air conditioning schematic ?

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Bertie
Joined: Sun 06 Oct, 2019 03:46
Posts: 43

  Z3 roadster 3.0i
Location: Montreal Canada

Z3 Air conditioning schematic ?

Post by Bertie »

Hi
I just had my A/C serviced after I fried in a 40 C traffic jam
. System was basically empty so I had the full evacuate , find a leak ,, fix , oil the compressor, and refill with a large amount of refrigerant .
The system had a leaking O ring on the connection to the evaporator
The mechanic said the condenser fan was not working , he is looking for a replacement , meanwhile the A/c is working well without a fan .
Do I really need the fan ? Is there a thermostat which controls the fan ?
I can't find a schematic of the A/C system, any details of the A/c loop , or even a wiring diagram for the fan
Any info on the A/C system or other advice will be gratefully received
Bertie

LaRy
Joined: Mon 12 Nov, 2018 17:47
Posts: 72

  Z3 roadster 2.8

Re: Z3 Air conditioning schematic ?

Post by LaRy »

I just have the lectric drawings for the -98, but most probably it is working in the same way. The engine control module is supposed to start the fan continoulsy at low speed. You have 2 fuses for the fan, are those checked?
You have a low speed fan relay, in my case no K21, is that working? In high speed, relay K22 should be working.
I would efinitely start looking at fuses and the relays.

Bertie
Joined: Sun 06 Oct, 2019 03:46
Posts: 43

  Z3 roadster 3.0i
Location: Montreal Canada

Re: Z3 Air conditioning schematic ?

Post by Bertie »

Thanks
That's a big help , could you send a reference so that can find the schematic or perhaps e mail a copy to " phing @ videotron.ca "
Cheers
Bertie

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Robert T
Site Admin
Joined: Mon 12 Jun, 2006 10:35
Posts: 10110

  Z3 roadster 1.9
Location: Cheshire

Re: Z3 Air conditioning schematic ?

Post by Robert T »

Bertie, there is a link to the schematics in the knowledgebase. Look for ETM (Electrical Troubleshooting Manual) in the index.

Cheers R.

Sent from my SM-G960F using Tapatalk

Arctic Silver '99 Z3 1.9 & Black '59 Frogeye 1275cc
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Bertie
Joined: Sun 06 Oct, 2019 03:46
Posts: 43

  Z3 roadster 3.0i
Location: Montreal Canada

Re: Z3 Air conditioning schematic ?

Post by Bertie »

Thanks Robert
I missed this in my troll through the Knowledge Base . I was looking for a reference to A/C or Climate Control systems;
I will check fuses, relays and connections before looking for a new fan.
Cheers
Bertie

LaRy
Joined: Mon 12 Nov, 2018 17:47
Posts: 72

  Z3 roadster 2.8

Re: Z3 Air conditioning schematic ?

Post by LaRy »

Good to check relays. My impression is that those are broken due to age. In the past two years, I have been changing 3 relays with broken magnetic coils.

Bertie
Joined: Sun 06 Oct, 2019 03:46
Posts: 43

  Z3 roadster 3.0i
Location: Montreal Canada

Re: Z3 Air conditioning continued

Post by Bertie »

The saga continues
I have checked the relays and fuses [ except fuse 48 a 40 amp fuse which is in the auxiliary fuse box ]. Where is this ??
I,m not convinced I really need this fan which pushes air through the condenser , which sits in front of the radiator which has it's own engine driven fan
The radiator and fan keep the engine cool even sitting in a 40 c traffic jam .All the cooling air for the radiator passes through the A/C condenser so the engine fan may be power full enough to to cool both the A/C and engine ??
This may be thermodynamic dreaming .I will probably have to take out the fan , this seems to require stripping out a lot of the front end to get at the fastenings ? I want to try this as a DIY project since it would l need lots of expensive garage hours .
Has any one done this and can offer advice ? I've seen some U tube videos [ mostly wobbl;y and unhelpful ] for other BMWs . but nothing specifically for a Z3 .
Cheers
Bertie

LaRy
Joined: Mon 12 Nov, 2018 17:47
Posts: 72

  Z3 roadster 2.8

Re: Z3 Air conditioning schematic ?

Post by LaRy »

I'm not sure, but some odd fuses can be found in the box to the right in the engine bay. In the same area as you find the car computer.

Bertie
Joined: Sun 06 Oct, 2019 03:46
Posts: 43

  Z3 roadster 3.0i
Location: Montreal Canada

Re: Z3 Air conditioning The story continues .

Post by Bertie »

Hi
The big electric fan in front of the radiator is called the " auxiliary cooling fan " in some of the literature I've discovered . I think this is a misnomer , and that the cooling sequence for the engine and air conditioner is :
All cooling airflow passes through the air conditioner condenser to the engine radiator
The cooling fans operate in sequence
Electric fan operates at low speed low speed at start up
If more cooling air flow is needed
Electric fan goes from low to high speed
Finally the engine driven fan kicks in .
I have a dead electric fan but no engine overheating issues even in extreme conditions [ 40 C stuck in traffic jams] but i have not used the refilled A?C yet ! I have no idea of the additional cooling load from the A/c .
The 64k Question Do I need to replace the electric fan ??
Any advice ?
Bertie
PS Where is the Auxiliary fuse box and Fuse 48 ?

LaRy
Joined: Mon 12 Nov, 2018 17:47
Posts: 72

  Z3 roadster 2.8

Re: Z3 Air conditioning schematic ?

Post by LaRy »

I would not give up the fans so easy. 2 motors broken at the same time....... No. Make a resistance test, I would guess something like 1 Ohm, if it is an open circuit, fan motor is broken. I would have made a jumper straight from + to the fans to check if working.
Some facts how it is working:
The ECM turns on the radiator fan at low speed when the air coditioner is operating. If the secod step of the radiator temperature switch senses high engine coolant temperature or the refrigerant pressure switch detects high refrigerant pressure, it starts the other high speed fan.
First check by holding your finger on the low speed relay, that you can feel a klick as soon as you or someone else starts the AC. If not, relay or most probably the fuse is gone.
Start the AC and when low speed relay is removed. Check for voltage by using a voltage meter in the relay socket. Normally it is terminal 85 / 86 for the coil. Check also for continous 12V power at terminal 30 at the relay socket.
Personally I'm feel rather sure that a fuse is blown as neither fan is working.

Bertie
Joined: Sun 06 Oct, 2019 03:46
Posts: 43

  Z3 roadster 3.0i
Location: Montreal Canada

Re: Z3 Air conditioning schematic ?

Post by Bertie »

Lary
I have a 2001 Z3 3.0i which has only one huge fan , the first thing you see when you open the hood . The only obvious thing like a power feeder to the fan is a 3 wire connector on the right hand side of the radiator . I am unable to separate the connector to see if there is current to the fan .I'm reluctant to try lethal force since the BMW electrical info says the fan power feed is underneath the radiator ?
Biggles

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