Somebody please help! Heater problems

Post Sun May 24, 2015 2:38 pm

Hi there, wondering if someone can help. My heater on my e30 325i 1986 does not work AT ALL. If I brigde the relay or manually operate it it works on all four speeds. I have traced the signal wires and it looks like two go into the fuse box (k7 relay to k5?) then fuse 20 back into the car and then one goes to the instrument cluster (blue plug). when operating the fan switch what signal wire tells the relay to close its contacts. I think this is where the problem lies as tried relays and still the same. Can someone please help me been stuck on this for a while. I have also changed the fuse box so cannot be that. Many thanks Joe.

Post Sun May 24, 2015 2:45 pm

Sorry fuse 19*. Fuse 20 is the power wire the the control switch

Post Sun May 24, 2015 3:07 pm

Do the reverse lights work?

Post Sun May 24, 2015 3:21 pm

Hi there. Yes the reverse lights work. Thanks Joe

Post Sun May 24, 2015 4:28 pm

How about the door mirrors, windows and sun roof? (assuming you have an electric sunroof and windows.)

Post Sun May 24, 2015 4:44 pm

The sunroof is manual as the windows. The mirrors are electrical the left side doesn't work at all but the right side works vertical only. I know there connected but it does not make sense that vertically it works but horizontally it doesn't?

Post Sun May 24, 2015 5:42 pm

It seems to be that whatever tells the relay to close when the ignition is on isn't doing so. The blower will operate on all four speed when I manually close the relay. What sends the power to the relay to close the circuit. Many thanks

Post Sun May 24, 2015 5:47 pm

Have you checked the Starter motor wiring? Especially the small wire with the 8mm connection, is it tight?

Post Sun May 24, 2015 6:04 pm

I have just checked the starter and there is a red wire screwed to it. A yellow and black wire with a connector to it (signal for starter?) but I also found a black and green wire on the side of the starter which is cut and not connected to anything could this be the signal wire for the relay as it's the same colour? Hopefully it is and there lies the problem? Thanks Joe

Post Sun May 24, 2015 6:26 pm

The heater stopped working when I replaced the radio. I think that the fan was acquiring power from the antenna curuit. Is this possible? I would still like to get it right tho. Just trying to work out the pervious method from the insane techninian!

Post Sun May 24, 2015 7:21 pm

The black/green going nowhere should be the cause of your problem, BUT this should also stop the mirrors working, so we may have the possibility of some bodged wiring.
The purpose of relays K5 and K7 is to disconnect certain electrical items in the car while the engine is being started. This is to divert all available power to the starter motor, and to prevent possible damage to the electrical items being caused by the lowered battery voltage while the starter motor is operating.
The power feed to both the heater fan and the door mirrors is via K7, and the roof, windows and heated seats are fed via K5. If none of these three are fitted to your car, K5 does nothing, and can be removed.
The coil of K7 is fed from the same ignition switched power source as the reversing lights, through fuse 10, which is why I asked about them earlier.
The other end of the coil is connected to the green/black wire, so if this is earthed with the ignition on, the relay closes and power is applied to the mirrors and fan.
The method of earthing this wire varies slightly between pre and post facelift models ('87 could be either!). On facelift models it is connected to live side of the the main windings of the starter motor, which have a very low and insignificant resistance to earth, as far as the relay coil is concerned. When the starter is operated, 12 volts is applied to the windings by the starter solenoid, so the relay switches off.
The pre facelift arrangement connects the 'black/green' to the live end of the starter solenoid instead, which has a much higher resistance to earth than the motor windings, but still should be low enough to switch the relays on. The 'black/green' on pre facelift models is actually black/yellow.
Any chance that your car may not have a) the original engine, and b) the original engine wiring loom?
Pull out relay K7 with the ignition on, and see if it clicks when you pull it out and again when you plug it back in. Do the same with K5.
Do the door mirrors work (as far as they already do) with K7 out?
The door mirror problems are common, and likely to be a combination of a faulty switch in the driver's door and possible problemns with the A pillar plug and sockets.

Post Sun May 24, 2015 7:57 pm

Hi there. Thank you for the detailed response. Yes the wiring loom has been changed in the vehicle. There is a black/yellow wire going to the starter motor but as you said the black/green should be for facelift. Seeing as the loom has both maybe it's a facelift loom and therefore the black/green needs to be connected. I will try this tomorrow along with the other things you have suggested. I believe with the relay out the wing mirror that already works still works. I reckon the wiring is bodged BUT I would like to get the fan working how it should be. I think the black/green has a lot to do with the fault. Hopefully it works tomorrow when I connect it!

Post Sun May 24, 2015 8:01 pm

Open up the C101 engine loom plug and socket (20 pin round, next to the fuse box), and check what is connected to pin 15 of both halves.

Post Mon May 25, 2015 11:08 am

Any News on this?

Post Mon May 25, 2015 2:15 pm

Hi there. Yes I checked the c101 plug pin 15 and it was black/green! I connected the cut wire to the starter and the heater started working! thank you all for your help. Joe!

Post Mon May 25, 2015 2:26 pm

Where did you connect it on the starter, and have you looked into the mirrors (excuse the pun) any further?

Post Mon May 25, 2015 4:28 pm

I connected it to the connector that the black and yellow wire was on. No I haven't looked into them yet but I tired them and they were still the same. I'm glad the heater is working tho but I'm a perfectionist and would like the mirrors working aswell. So just got to keep investigating. Thanks joe

Post Mon May 25, 2015 6:46 pm

Does your starter solenoid have four terminals or three?
If four, two of the terminals should have 13mm nuts, one 10mm and one 8mm. The large wire from the battery and a slightly smaller one from the alternator should go to the outer 13mm terminal, the black/yellow should go to the 10mm, and the black/green should go to the smallest one.
If your solenoid only has three terminals, the black/green should be connected to the inner 13mm terminal, which is electrically identical to the missing 8mm.
Anything wrong with the driver's door mirror is likely to be cured by replacing the switch assembly, and any remaining problems with the passenger mirror are then likely to be as a result of corroded pins and buckets in either of the two A pillar plug and sockets where the door looms connect to the body looms.
These plug and sockets have a rubber cover over them which must be fully fitted to the plug before it's pushed into the socket, but most by now will have subjected to an attempt to refit the cover with the plug in situ. This will let water into the plug where, as the result of two permanent live pins on the driver's side (see "red/black wire modification") rapid corrosion will occur. The passenger side only has power on pins when the ignition is switched on, so usually this side is in better condition.

Post Mon May 25, 2015 7:11 pm

Hi there. The starter motor has a 13mm with two lives to it (battery and alternator). The the bottom of that there is a spade looking connector that the yellow/black wires was connected to then to the top of the 13mm there is a smaller spade looking connector that nothing is connected to. If I put the green/black to the small one the heaters don't work. If I take the yellow/black wire off and put the black/green wore in its place the heaters work. There is only one 13mm nut and to the left is a wire the earth I believe. Many thanks joe

Post Mon May 25, 2015 7:19 pm

If it has a spade connector it's a pre facelift motor on a facelift loom. Heaters will work with the black/green connected to the black/yellow, but for the reasons I stated further up the post, it's preferable to connect it to the inner 13mm terminal.

Post Mon May 25, 2015 7:55 pm

Hi there. What is suppose to go to the inner 13mm apart from the black/green wire? Thanks Joe

Post Mon May 25, 2015 8:00 pm

Graystar09 wrote:Hi there. What is suppose to go to the inner 13mm apart from the black/green wire? Thanks Joe

Either a solid link or a copper braid to the starter motor itself.

Post Mon May 25, 2015 8:04 pm

Yes that is what is on there. Should I connect the green/black wires to the one then and leave the yellow/black where it was? Many thanks joe

Post Mon May 25, 2015 11:58 pm

Your car and engine loom have the post facelift set up (no black/green on either side of the C101 on pre facelift), and BMW must have had good reason to revise the arrangements, so it would be preferable to crimp or solder a 8mm int. diameter ring terminal onto the black/green and fit it onto the inner large stud.