docmirror

Behind and below the air cleaner box. You need to remove two 10mm nuts to get the air cleaner box off, and the heater control valve is slightly to the right. More than likely, the flap inside the valve is damaged so even if you wire it shut it will still allow hot water to circulate. It's best to block off the supply line to the heater valve with a marble or something so that you are sure it doesn't circulate hot water. You can go back and solve that later when you need heat.

There are several write-ups in this sub forum for heater control valve work. Use the search to find one, and follow the instructions.

Captain_Slow

Inside engine bay, passenger side firewall. It is white and black plastic. You can see it just behind and blow the air cleaner. Not an expensive part, which is good because it has a rather short lifespan. They can fail gradually, allowing increasing amounts of hot water to enter the heater core, gradually warming the air coming out of the vents. Mine still works. But when it fails I'll consider putting in a manual valve I can reach in and open as much as needed during cold months and close in summer (Got the idea from my Unimogs...they had two screw valves that could completely shut off the heater circuit...and were also the crude method of adjusting heat - and beautifully simple).

Jfrahm

Although rare I have had these pass coolant when closed so that I got heat all the time, in which case I replaced it with an Audi 5000 or Ford Escort heater valve, more robust than the OEM part IMO. But any replacement is better than a bad one.

conate

Thanks for the input. Will comb threads for some pictures. Not to sure about marble procedure.

Landshark87

http://jenniskens.livedsl.nl/Technic...4/MyTip431.htm

good pics and info above ^

notes:
- black side toward the ENGINE
- replace the short hose, too. (special part, one end is tapered)
- attach the hose to the valve, then slide it on to the rear hose. its been a while, i may have used a SMALL amount of grease to slide on to the rear hose
- you will invent new swear words because of how little room you have to maneuver in that spot, but it will fit (especially if you attach short hose first)
- have a beer, then fix the rest of the HVAC system that doesn't work

whiteNSXs

No need for AC in Las Vegas?!

Jfrahm

He probably means "heat" but even with the air not directed through the heater core, if it's full of 200 degree water it heats the cabin nicely and the AC really struggles.

conate

Landshark87.......thanks for the links...I am a visual guy and now I understand the system.

Indy Rev

I have the same issue. I did zip tie the heater valve, but still get a fair amount of coolant pass through. Its atleast bearable now. Its on my list of projects.

Landshark87

i've done it before on the 928 i had 12 years ago, and when i went to do it on my current one, i was thinking, "WTF, this is ridiculous!?!?!?! am i insane? how the hell...."

...then after some fiddling it goes right on.

ALKada

Took me around 20 - 30 minutes to replace my heater valve with all parts in a kit from Roger. Inexpensive and was well worth the time. www.928sRus.com

docmirror

Remove hose clamp to heater control valve. Pull hose off end of valve. Look inside for flapper vane. If good with seal intact, proceed to wire off control lever at vacuum actuator. If not good, locate, lubricate, and stuff one each, approx 5/8" spherical cat's eye glass marble in end of hose. Reattach hose to valve. Drive in comfort until cold weather. Reverse procedure above.

conate

Just bought the MB version from FCP Groton. Going to replace due to the fact that i occasionally need heat here in CT. Especially in the Fall. I will need to contact Roger for short hose piece.

chitown928s4

You dont have to sip tie it. Pop the arm off and put on closed position. It makes a difference.

86gtvert

Ok. So I disconnected my heater valve but I am still getting TONS of hot air coming through my vents..ideas?