It's unseasonably hot in Phoenix and my the AC in my 83 300TD is still driving me batty. I had been getting only cold or hot, but that's now become luke warm and hot. I've replaced the temperature regulator, the temperature control unit (the type with the horizontal buttons), replaced the monovalve, fixed the tube behind the glove box that runs to the sensor. Had compressor and other part replaced so there are no leaks. Could be the temp sensor in the dash is bad, though that seems an unlikely part to wear out.
One thing I noticed--there is a hole in the firewall between the battery and the monovalve where the remains of a hose are visible. Looking at pictures of other cars I see a hose that points downward but looks more like some kind of air intake or some such. I haven't been able to find out what exactly it is. I'll attach a picture of a car with it intact. Does anyone know what this hose does and whether it might be affecting the AC performance?
Any and all help will be much appreciated. I'm sweltering!

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That is just the drain for the cowl area. Those hoses often rot but it would not affect your climate control at all.


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1985 Euro 300TD Turbo

Thanks, disqo. I figured it couldn't be that easy.