[williamoss]

I just had a complete failure of the heater control Valve. It is made of plastic and is actually made in two pieces one of each fits inside of each other. It is located on the passenger side of the car, it extends from a metal rod into a 3 inch long rubber connection hose into the valve and then connects to the top of the water pump I think. When it came apart I lost all the coolant in the car. As our cars age the seals and plastic parts are drying up. This part was only $72.00 and easy to replace by itself. I decided to replace all the coolant hoses to make sure all were new and in great shape. Perhaps you should do the same. You can see the top of the valve as a black round top just under the power steering fluid chamber and behind the oil filter.

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[pure&simple]

+1



I went through that same scenario the first time I turned on the heat after buying the car back in 2008.

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[94SilverCab]

This is on my list of 5 year parts, I hope to never have a failure...



Jay

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[SILVY968]

USE THE METAL AUDI PART, THE PLASTIC ONE WILL FAIL AGAIN(I KNOW).

SEARCH THE SITE FOR THE PART NUMBER.

BRIAN

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[Langley968]

A few months ago when I had to replace the water pump (+ rad, all hoses, thermostat, timing belt, balance belt, front seals, tension pulley, idler pulley, rollers - all the "while your in there..." items) the heater valve was also replaced because it was showing signs of leakage. Upon reading this thread, I am glad. <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />

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[DayDreamer]

Been there, done that, left puddle at the traffic lights to prove it <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[nissanite]

These also fail another way.



The vacuum part leaks. When that happens the valve default opens all of the way & the heater gets hot. My A/C system had warm air coming from the vents.

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[craigawoodman]

My car has hot air coming from the vents. The climate controller has been rebuilt. I thought that there was a control valve up near the windscreen as well?



So if I am getting hot air throuh the vents, I need to look at this (and also possibly the valve above the firewall/near the windscreen as it could be letting hot coolant through to the heater?

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[Cloud9...68]

In addition to proactively replacing their HCV, preferably with the metal Audi one, everyone should order the heat shield from Design 1 Racing. You'll never have to deal with this part again.

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[Grandpa#3]

The Heater Fail Safe defaults to full heat. Remove the panel above the driver side right foot. The Plastic clips break that hold the flapper door rod closed. Check out Clark's Garage.com at the link below for the 944 85.5> as it is the same on the 968.



http://www.clarks-garage.com/shop-manual/hvac-01.htm



Cheers,

Larry

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[flash]

yeah - the failure is the glue they use to bond the two pieces with - it's the same glue used on the early power steering reservoirs (the clear ones) - that also fails for the same reason - the heat in that area is significant - that was the primary reason for me coming up with the heat shield



a few people have used the metal valve, and if you are willing to fiddle with the vacuum fitting and hose orientations, it seems to work, though i did hear that it responds differently to the vacuum than the OEM unit - i have no idea exactly how though



the OEM piece is only $17.25 at pelican - since all coolant hoses should be changed at 5 year intervals anyway, and the OEM units almost always lasts at least that long, it seems to me simple enough just to stick with it

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[Scott Collins]

I keep an extra one in the glove box, along with other "must have" likely to fail components.

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[Cloud9...68]

Heat shield + new plastic HCV = likely long service life



Heat shield + metal Audi valve = never have to worry about this again!

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[flash]

having already suffered the vacuum leak there, and in the dead of summer, i'm not sure i'd want to go through that again, knowing that i had to do an adaptation to the vacuum port to make it work - i hate vacuum leaks

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[tamathumper]

Was the vacuum leak caused by the failure of the OEM part, or from using the metal Audi part? You implied that it works differently in a previous post.

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[flash]

i have been told that the rate at which it opens and closes is different than the OEM part - that might make the heater work differently



the vacuum issue is due to the fitting not being the same size as the OEM unit, which then requires adaptation to make the seal - this has varied from clumsy odd solutions like "jb-weld" to inserting an adaptor hose to couple things together - just not cool either way - to me, that is just asking for an eventual failure that would cause the heater to go on full at likely the worst time (like it did for me)

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[Cloud9...68]

It's been many years since I installed my Audi metal HCV (working flawlessly), but I do seem to remember having to modify the vacuum line to make it work, but I don't remember what I did. It's held up well, though, so it was a robust solution. I'll have to take a closer look, which will be easy since my engine is in pieces. I don't remember it being a big deal, though, and the heater comes on very fast, and blows blazing hot air on demand.

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[jfrahm]

I generally use a small ziptie on the vacuum fitting and use the stock vacuum line. Now that I have a supply of very flexible silicone vacuum hose on hand, if I did it again I might use that hose to replace the factory J bend hose. This modern stuff adapts sizes very well (start small and it'll stretch.)



I have not had a problem with one of these Audi valves and have not had to reconfigure hoses or anything unusual other than ziptying the vacuum line. I have not noticed any issues with heat control as a result of the swap but I suppose anything is possible.



The stock valve is inexpensive but IMO the risk of dumping coolant is too great even if you change the valve out every 5 years. Also I can get the metal valve fast (same day) at my FLAPs if I decide I need one.



I have used both the metal valve that looks like a regulator with offset in/out fittings and the metal/plastic valve with a little bellcrank operated flap valve. I prefer the former but it may not fit as well as the latter. The metal/plastic valve may be harder to find these days. It also looks like a part that will one day leak but probably not pop apart and soak your RF tire with coolant.



I run the all-metal one on my 928 without trouble. On a 968 it might fit better with a slightly longer stub hose but that's something you should replace with new anyway if you are in there. It's like $18 locally.



http://static.summitracing.com/global/im...4671_m.jpg



-Joel.

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[Cloud9...68]

Joel,



My experience (other than the 928 ownership peice) mirrors yours exactly. I was planning to secure my hose with a zip tie for extra insurance when I put my engine back together. The metal HCV, especially when used in conjunction with the heat shield, just seems like a bullet-proof solution, a rarity in the world of nearly two-decade-old sports cars.

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[jfrahm]

I had to replace the stock valve in my 928 because it would close and hold vacuum but still flowed enough coolant to make the cabin very hot. The AC was also broken at the time. I'd just bought the car and had to drive it home 1000 miles through a heat wave. I was able to pinch off the heater hose with a clamp I bought at a hardware store after the first few hours of driving but I still roasted. 44oz iced teas and sunflower seeds, and a t-shirt pinched in the window for some shade. It was a good run.

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