A word of warning - this will be a long writeup - but believe me, it isn't hard to change out the valve. There are two different types of heater core valves on E30s, so you need to see which one you have before you order one since they were freely interchanged on the assembly line but are NOT interchangeable when replacing parts. To determine which one you need, you'll need to find the heater hoses in the engine compartment where they attach to the heater core lines at the firewall. These are located on the driver's side of the engine on the firewall(in LHD cars) with the inlet hose located directly above the outlet hose. You need to look at the upper heater core line (the inlet line) to see what material it is made out of - plastic or aluminum. Depending on how far the hoses are placed onto the heater core lines, you may need to loosen the hose clamp on the upper line and pull back on the hose to expose the line enough for you to determine what it is made out of. It can be kind of a pain, because there isn't much room down there around these lines. IIRC, I could easily tell just by looking down there on my car and didn't have to remove anything.
If the inlet line is aluminum, you will need to order the valve for cars with the aluminum inlet, which looks like this:
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If the line is plastic, you will need to order the valve for cars with the plastic inlet, which looks like this:
Now that that is out of the way, we can talk about how to actually replace the fool thing. First, you'll need to remove the underdash fiberboard cover from the driver's side - three turn screws where it meets the dash and one or two underneath, and it should be free. Disconnect the chime speaker and move that cover out of the car so you have room. If your car has the underdash knee bolster (no idea what year your car is??), you may have to remove it - I'm not sure since mine doesn't have one. Next, you'll have to remove the center console since the heater core and pipes are underneath it. You will need to remove the rear half of the console first - pull off the parking brake rubber boot and pull out the rear ash tray to reveal a plastic nut. Remove that plastic nut and you can then lift up the rear console (there is a light bulb that illuminates the rear ash tray - pull that out of the console). The front half of the rear console just has tabs that slide into notches in the front half of the console. Get that thing out of the way. Next, remove the two screws that are in the storage well in front of the front ash tray. Remove the ash tray and disconnect the wiring harness from the cig lighter and the ash tray light bulb. You'll now need to remove the shifter surround from the console - no idea how to do that on an automatic since mine is a manual - you'll have to figure that one out on your own. Once all that is out of the way, there is another nut down underneath the shifter that fastens down the rear half of the front console. Remove it. Push up on the window switches from the bottom to pop them out and disconnect the wiring harnesses from them. If your console has never been removed before, there is probably a little screw/bolt located above where the ashtray is located that connects the console to the dash - you'll need to remove it to free the console. I'm not sure what kind of screw/bolt it is since mine was missing when I bought my car. Follow the console around the side to WAY up under the dash and you'll see a large black plastic "screw" with a straight-blade notch in it. Turn this 90 degrees and pull out gently on the console and it should free it - there is one of those on both sides of the console. The console should now be free and you can maneuver it out of the car.
Now, direct your attention to the driver's side footwell under the dash. You should be able to easily identify the coolant lines entering the car from the engine compartment. One of them will have the valve in it (big gray plastic valve)- see the pics above for reference. Disconnect the hoses from the lines in the engine compartment and let the coolant in the lines drain (no need to drain all of the engine's coolant unless you want to change the coolant while you are at it). Now, the problem is that the lines in the passenger compartment and the heater core will still be full of coolant and there is no way to remove that coolant until you disconnect the lines from the core, so have something in there to catch as much of the coolant as you can - a plastic cup and lots of towels, etc, or you will end up with a good amount of coolant on your carpet. You should be able to see how the lines are fastened to the valve and the core - pull out the little brass bolts but DON'T LOSE THE NUTS - they are square nuts that are designed not to turn while you are tightening the bolts, but they are NOT captive nuts, so they will likely fall out when you remove the bolts. When you get the pipes removed, the coolant will drain and you'll see that the connections are sealed with an o-ring. Pull out the old valve, disconnect the wiring connection (it's snaps in VERY securely). Replace the o-rings and reassembly is the reverse of disassembly. Bleed the coolant system with the heater on to get the air out of the heater core, and you are done.
Wow, that was long, but it really isn't that bad, especially if you've ever had the console out before. Also, for future reference, the A/C expansion valve is located on the opposite side of the A/C heater unit in the same spot as the heater valve but in the passenger footwell and requires all of the same preceding disassembly steps.
Hope that helps.
![[;)]](/images/smilies/wink.png "Wink [;)]")
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