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Cooling & Heating

AC Expansion valve

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On Series I it is located where the AC pipes go through the bulkhead (at least for a LHD car, I have no idea on RHD). The bulkhead bridge is an oval metal part surrounded by rubber, with two pipes leaving it. It is bolted onto a similar part on the inside of the cabin which is a part of the heat exchanger, literally through the expansion valve assembly. What you do is (of course once that the remaining gas has been evacuated) to unscrew the two nuts that hold the oval part on the engine side of the bulkhead. Then the oval part with the pipes can be removed carefully, as it plugs into the expansion valve assembly. The pipes themselves are slightly conical and have O-ring seals, as do the pipes that go from the expansion valve into the cabin. Therefore be careful when doing this as the valve may end up on the part you are removing, it's only held in place by the pipes, and the bolts go through holes in it straight from the cabin part to the oval bulkhead part that you are taking off. You cannot fit it wrong because the pipes are of different diameters: it only can be fitted one way for the pipes to plug into it.

Air Conditioning

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What is "Climate Control" (on a P reg, 1996 XM TD 2.5) as opposed to Air Conditioning?

Finding the cause of overheating

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Check the coolant fluid level on a cold engine. If it is low, especially if you have a coolant leak, you might have found the problem right away. Otherwise, start with checking the fuses #1 and #4 on Series II models or #5 on the older ones. If they are OK, put your finger on the leftmost relay behind the fuses; when you turn the ignition on (don't start the engine), it should click. If it doesn't, replace it. If you have electric windows fitted, either the second relay from the left or the second from the right would be of the same type as the one serving the cooling fan; you can use them as a quick roadside replacement.

Leaking heater matrix

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If the carpet is constantly wet in the footwell and you lose coolant slowly, no doubt, the heater matrix (the actual heating element) is leaking. There are two pipes crossing the bulkhead behind the engine, on the right side. Look up beneath the lower trim panels in the cabin: the pipes go through a black box, the valve you open and close by turning the red-blue control knob on the center console. If the valve is opened, the hot coolant flows through the heating element, transferring its heat to the air blown through it.

Leaks in the cooling system

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Avoid products which claim to block any leak from the inside (Holts Radweld and similar). They can clog more than the leak itself, the heater matrix or the smaller passages inside the engine might suffer. Do it properly and thoroughly instead.

Retrofitting a coolant temperature gauge

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This is rather easy on the Series II models (but read on, we have some ideas for Series I, too). The modification has been done on various models already: 15 TGE, 19 TRI, 19 TRS, 17 TZD turbo, 19 RD, 19 TZD. As far as I know, the exact same procedure should apply to all BX 15/16s (but it would be nice if someone could try and inform me about the results). Part of the modification might work on a BX 14, too (temperature meter but no warning lamp).

Squeaking blower motor

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The theoretical solution is plain and simple: lubricate it. In practice, however, this means removing and disassembling the motor (as described in the answer to the previous question)—not something you would want to do every six months or so, wouldn't you? But if you do it once, you can modify it so that you can lubricate it later as often as you feel necessary without going through the hassle of removing it any more.

Indeed, the word modification is an overstatement. All it takes is drilling a small hole in the casing. The motor is located in the left side of the housing, secured by two bolts (to remove it, its two connectors must be removed as well). There are several radial reinforcing fins of the plastic half-case facing the engine between the center part housing the motor and the perimeter. The upper vertical one is about 1 cm wide and is situated exactly above the motor mechanism. Drilling a small hole in the lower third of this fin will be more than enough to allow the motor below to be lubricated whenever necessary. After that, it can be covered with adhesive tape to prevent the ingress of dirt.

Trouble with the blower motor

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If it's not working at all, start with checking the fuse #2. Remove the lower shroud of the dashboard (secured by seven screws). A relay is fixed to the right side of the steering column. Turn on the ignition. As you turn the blower speed knob to the full speed position, the relay should click. If it doesn't, check its feed (connector #1). Then jumper its connector #2 to the ground, this time it must click. If it doesn't, it's faulty. If it clicked this time but it didn't when you have just turned the knob to the full speed position, you have to check the heater controls.