Fixes - Climate systems

Remove/Replace Heater Core


The first one documented was probably done by Stefan Borch.
Meanwhile there have been some experts who do it faster with fewer parts than removing the whole dash. Johan has done it too. See his website too. Now Cyril from the E34 board has a write up done and that is very good. Although without pictures.
BTW: The record time for this job now stands a 4 hours.


Since the weather was nice I decided to tear into the dashboard.
My symptoms: low coolant message after a few days when using the heater. No coolant on ground. Positive smell in cabin but no mist on windows as often described.
My findings: small corrosion at top of passenger heater element.
Tips: One does not have to remove the upper dashboard as mentioned on a 7 series page. The center rear and forward console has to be completely removed. The black panel holding radio, climate control and computer can be swung out of the way while disconnecting radio and climate control and lighter keeping computer connected. The components don't have to come out individually. Behind this is the plastic covering over the heater core with 10 clips and a few screws. As I didn't use the heat for 5 momths it can be removed without draining coolant or clamping the firewall hoses but place some paper towels under it as the core is leaned forward and lifted out. I let about 1/8 cup of coolant drip while replacing the towels. Clean all inside plastic surfaces well to get rid of coolant vapor residue. Use new rubber washers on the pipe connections (usually supplied but if not buy some). Assembly is reverse of removal. Don't forget to reconnect the cigarette lighter (I did and now have to figure out how to reconnect it with minimal disassembly).
Total time to replace and reassemble: 4 hours. I took five however, spending time to clean all switches and dashboard parts on reassembly.

I didn't document with photos but in case anyone wants to tackle the heater core replacement, here are some instructions. Perhaps it will be good for the archives at any rate. I, of course imply no guarrantees of success and take no responsibility for your peril (I'm not a lawyer). But seriously, it's not too hard.
Tools: Philips #1 and #2. Socket or wrench 8 or 9mm and 13mm. Small straight blade screwdriver for prying. Flashlight.

1. Pry off vertical black strips to right and left of center black console housing the radio, etc to reveal screws.
2. Pry off wood dashboard strips below instruments to reveal screws.
3. Remove drivers lower dash panel via 6 screws
4. Open/lower glovebox (can keep attached by straps).
5. Remove shifter knob, leather boot surround, wood surround (reach hand in and pop up forward edge, slide forward and up (towards ash tray) to clear tabs at edge of wood closest to you).
6. Remove rubber and foam around shifter rod.
7. Pry off color-coded cap from screw at junction of front and rear consoles (where center recess is between arm rests).
8. Unscrew said screw.
9. Pry off leather parking brake surround and lift up a little.
10. Unscrew screw at bottom of opening around parking brake which holds down driver's side of front console to rear console.
11. Pry off rear black panel where rear airducts are located.
12. Use 8 or 9mm socket to unscew two side bolts holding rear console in place (I couldn't easily budge the 2 phillips screws but this is an alternate).
13. With rear console free, slide it back 5 inches but don't need to lift up.
14. Using 8-9 mm socket, unscrew black plastic bolt holding rear of front console in place on a ridged plastic tab.
15. Up front, unscrew single phillips screw holding small carpet piece along right and left sides of transmission tunnel (e.g. near accelerator pedal) and slide piece of carpet forward and lift off.
16. Unscrew black phillips screw holding front bottom of center console to a brass metal tab on both sides.
17. Unscrew any of the four remaining screws at black plastic console holding radio, climate control, etc., revealed in step #1
18. Attempt to free the front center console. The window switches need to be pried up and disconnected along with the hazard switch. I don't have ASC but this switch, if present, should be disconnected. Un plug white connector holding wires to cigarette lighter.
19. Try to swing upper center black console containing radio to the right. As you do so, disconnect radio wires, climate control cables, and climate control wires. Look at how connectors come off carefully; one has a small lever that needs to be pulled which helps eject it. I didn't disconnect the computer but this could also be done.
20. Swing this assembly to the right and balance on open door of glove box (don't scratch your wood - use a protective paper, cloth, etc.
21. Revealed is now a big black plastic enclosure to the heater core. Disconnect temperature wires at white connectors on each side.
22. Unscrew two phillips screws at front base of enclosure.
23. Un-bolt two shock absorbing mounts at base of front enclosure.
24. Remove 10 clips holding enclosure back (facing you) to the front half. The clips at driver's side may be tough to spot and access due to the obvious wires and metal support rod, but this is "do-able".
25. Clip tie wraps holding t-shaped wire loom in front of enclosure and push this and climate control cables up, out of your way.
26. Remove enclosure panel. Start at passenger side and pull towards you, then slide to passenger side and free driver's (left side) from behind wiring etc.
27. Now you see heater core!
28. Un-screw each of three pipes slowly and make sure paper towels are on hand. I didn't drain coolant and did lose 1/4 cup from top of core and pipes, but that's all. Make sure towels soak up any draining coolant and not your carpeting.
UPDATE: from me78569 of BimmerForum "Check the ends of the plastic pipe at the heater pipe connection carefully as they often crack.

29. carefully bend/move passenger element pipe torwards you to make room for removing core (just a little).
30. Core is only held in place by the three pipes. Pull top of core forward torwards you and lift out of dashboard.
31. Clean plastic box well.
32. Have three new washers on hand for attaching new core and pipes.
33. Test the new core to rule out leakage by reattaching the climate control and running the car.
34. Assembly, is, well reverse of above.
35. Bleed the coolant system.
I hope I haven't missed anything. Good luck.

"First two photos from johnD"

Here are a few pics I took after I had removed the heater core from the vehicle. No need to remove the entire dash.
I spent a couple evenings replacing the heater core.
Very Little needs to be done to this side Unquote
UPDATE: from me78569 of BimmerForum "The only thing I did different was I didn't remove the servo motor on driver side to get to the one bolt that holds plastic to aluminum pipes. I left the servo on and just used 1/4 ratchet with a extension and swivel. It worked really well. I took pics of all the wiring and connectors so I knew how everything went back. "

Photos below from the ever valuable Take of Japan

Use plastic cup to catch fluid!

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Fixing noisy AC compressor

Intermittant noise from the AC compressor?
Shogun's 750 was making an intermittant rubbing noise that was somehow connected to the AC.
We narrowed it down to the AC compressor which had not been touched since delivery except for switching to R134a.
Our first thought was that it was the clutch - it can be replaced fairly easily without removing the compressor.

HOWEVER, we replaced the inner clutch (ribbed pully) but found that the problem was that the shaft of the compressor had become worn where it supports the inner pully. The bearing appeared to be ok, but the shaft was shot. The inner pully was rubbing against the electro-magnet coil.
NOTE: we did not use any special tool to hold the driven clutch plate - simply wedged a steel block against the arms on the outside of the plate - when removing the 13mm nut. Definitely shade-tree mechanics at work.
The inner pully slides off the shaft once the circlip is removed.

From German E30 forum
shaft sealing change, denso instructions

old R12 compressor repair on a 750 with simple tools
shaft seal

the old R12 compressor for the 750 has on the underside a lock sensor

E32 750iL 11/88, E32 750iL Highline 03/90

Fix: Shogun replaced the entire compressor with one from an E31, switched the inner pully to match the E32 belt and recharged the AC system.
There are small washers that fit between the driven clutch plate and the inner clutch. The number and thickness must be adjusted so that the gap between clutch surfaces is 0.5 - 0.8 mm.

Resolder IHKA

When there is a problem with the IKHA, usually people suspect the control panel, the sword, water valves, and very often the flaps and stepper motors.
Flaps and stepper motors are simple things and can be checked very easy.
The sword's only function for the IHKA is that it is controlled/gets signals from the IHKA module, which sits behind the sword and has 4 plugs (white, blue, yellow, green, 2 each side).
The module is basically responsible for the whole IHKA functions AND (what many people do not know) also the rear window heater.
Inside the IHKA module there is the CPU for the temperature feelers, stepper motors, heater valves, which only carries out the orders (settings) thru the control panel in front of the driver and just acts according to the programs (which you select by pushing the buttons) selected by you.
So the module is the heart of the whole system or better to say the brain.
There are about 30 different modules available, depending on the options in the car when it was once ordered.
So when you buy a spare module (which I recommend for testing and emergency (used one is much cheaper)) first check the part number on your installed module.
Resolder all points in the system, even if you do not see haircracks.
Also when you remove the module in case there might be a defect, usually they can be resoldered/repaired. Also have a look at the connections where the 4 arrows are, which sometimes get loose or have a short connection.

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Repair brushes in blower motor

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Remounting flap actuator motors

The IHKA assembly is quite large, complex, and expensive. Quite often it is the small problems that cause you problems.
The heating cooling system on the E32 uses 10 air flow control flaps with 10 actuator motors.
Johan has created a fine page with all details/photos here, check the details. I'll wait for you here.

The main problem is BMW overkill. The flaps are opened/closed by cranks driven by powerful gear sets --- but the limit controls are too basic.
Each time you turn the ignition on, all actuator motors drive to their physical "limit", wait for 10 seconds, and return to the position dictated by the user controls.
Unfortunately, the limit is determined by some rather thin plastic (part of the actuator mounting base) and often the crank breaks the plastic which leads to
loss of heating cooling functions.

The DIY solution is to make a metal strap replacement for the plastic. The trick is find good mounting points for the strap since the IHKA case consists of rather weak plastic and the crank power is really high.

First, this shows the actuator motor with crank; Design movement (green arc) and the crank movement if the plastic is broken (blue arcs)

This shows a typical broken case. The actuator motor is mounted on the back of this plate so that the crank can be connected to the flap arm (the gray rod in the center)

This shows one arrangment created by a local BMW owner.
note the bolt and screws that hold the metal strap.

Here is a detailed view

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Room temperature thermistor:

The room temperator thermistor is set just behind the front of the control panel.

There is a small motor with a fan that passes cabin air over this thermistor -- so with age the thermistor can become incredibly dirty.
Carefully clean it with brake cleaner. Check that the solder joints are not cracked.

When clean, measure the resistance. The design values are given here

If the resistance is wrong for the temperature at which it was measured, the thermistor could be cracked --

It is a simple job to desolder the failed unit and solder in the new one.

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Room temperature thermistor fan

The heater control panel started to sound like there were mice in the panel, so I took out the control panel, removed the 3 plugs on the back, removed the plastic cover from the fan housing on the back, then removed the fan completely after unplugging the fan wire socket (2 wires). The fan is set inside of 2 rubber/foam halves to prevent vibration noise. Cleaned the fan propeller, used some lube spray on left and right for the bearing (hopefully it found it's way in), then made a test run with fan connected with 2 wires to the plus pole in engine room and ground.
No more sound, so installed everything and so far it works well. Will disassemble it once more as I forgot to clean the temp sensor inside, and I will use another lube oil which is used normally for sewing machines.
Check the control panel, worth to get the dirt out

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Clean-Repair the Water Valves

The water valves are shown here -- after removing the plastic cover plate.

Remove the 4 nuts holding the water valves down and unplug the two connectors

Loosen and remove the water pipe from the engine to the pump and the pipes to the heater cores.

Lift out the water valve assembly.

Loosen and remove the pipes to the pump

Unscrew the 6 bolts holding the top and bottom halves of the water valve assembly.

Use a minus driver to separate the two halves - carefully

This is often the condition after long time in service.

Clean the valves and determine if the sealing surfaces are still good.
These below are rather poor -- should be changed -- the stems are badly corroded.
Check the rubber seals for cracks -- if they become hard they don't seal well.

Here is a good set for comparison.

Replacement is the simple reverse of the above.
Note; under the black plastic lid, there are some wires and capacitors. If the solenoid coils show an open circuit -- some wire is broken --
you may need to force the lid off. This next photo shows what is under the plug mounting points. Looks like one of the bottom wires is broken.

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