A friend of mind just bought a '95 Civic DX w/ 160ish k miles on it. He paid around $1,800.00. He's having an issue where the A/C absolutely does not work, but neither does the plain cold air if you slide the temp slider to the blue. It gets hot as crap in there within like five minutes, even if blower is set to 1. I suggested charging the A/C before I got to take a look at it, but now that I see even the temp slider on the hvac control unit isn't working, I'm calling out the hvac control unit. What do you guys think?

 

Sounds like the coolant hose valve on the firewall leading to the heater core under the dash is stuck open. The temperature slider in the dash works by opening and closing the valve. Look under the dash to determine whether the slider is disconnected from the cable that operates the valve.

 

Well that, and also make sure the cable hasn't slid around in the 'clamp' so that no matter what you do with the slider, the valve doesn't close. (Mine was in that state when I bought the car - the previous owner was complaining about the [lack of] A/C).

It's such a stupid system. Everytime you get under the dash for anything, you need to make sure nothing's changed with the HVAC control cable 'clamps.'

Save yourself some future headaches = Once you get the cables where they need to be inside the 'clamps,' put a zip-tie on the cable on each side of the 'clamps' to keep them in-place.

 

There are two cables. One goes from the lever on the dash down to the mechanism shown in the first picture, which is on the bottom of the heater box under the center of the dash. When the dash lever is on cold the lever on the mechanism should be against the stop as shown near the bottom of the first picture. Then another cable goes from that mechanism to the water valve under the hood.

Wait until a decent warm day to test the A/C. Do not just charge it without knowing what is going on.

 

Yeah didn't plan on it. I have a set of gauges I'd like to get on there first to see what's in there currently.

Thanks for the suggestions guys... I'll let him know and see where we get.