sfierle

A quick review: My 1983's climate control always blows heat no matter the position. This a fairly new problem, A/C worked up until about a month ago. As I said, the car blows heat all the time, but yesterday I was fiddling with the controls and the A/C came on for a few seconds when I turned it on. After asking before and reading in the archives, it appears a sensor is the problem. I read a sensor is under the left headlight. Can someone be a little more specific? How do you access it? What does it look like? I'm fairly new to 928s and I need a little more help. I figured, as directed in the archives, I will check for a loose connection. Please help if you can.

the flyin' scotsman

Most 'always blows hot' issues stem from the water valve. It's located below the lower air filter housing between the engine block and the hose for the heater. The valve defaults open allowing hot water to be released into the heater and hot air into the car, despite what settings you have. Its operated by vacuum so once you located it switch the temp lever to the lowest setting and see if the arm moves (which closes the valve) If its faulty you can zip tie it closed until you get a new valve. You can also test the valve with a hand held vacuum pump attached to the port on the valve (white line).

macreel

sfierle... be sure you have reliable vacuum from the 4-way
connector forward of the brake booster. Sometimes the
blue&black check valve fails and vacuum goes away
(which you need to close/operate that water valve).


G'luck

sfierle

Thanks for the input, I will take at look at it sometime this week.

WallyP

If you will send me a standard email (not thru this forum), I will send you a paper on the HVAC system that might help.

My email address is techAT928gt.com - change the AT to an @

ROG100

Wally's write up on the HVAC system is invaluable. Take him up on the offer.

The outside sensor is mounted in the air duct that is in the front of the drivers side fender. The duct that feeds air to the alternator. The other sensor for inside temperature is behind the small grille top right hand corner of the center console.

There is a very straight forward write up on how to test the sensors and the HVAC controls in the WSM.

jlegault

I've had the same problem (and still have it!). My 928S is an '83 as well. You should have a by-pass switch turned on when you push the temperature control down to 65 (you should hear a 'click'). This will force the system to close the heating flaps to close. If your heater valve (the vacuum controlled coolant valve under the enginer air filter assembly) is not working, you will have some warm air through the door vents (that what happened in my case). If your heater valve is working properly, you should get cold air goig out of all vents. My outside air sensor is deffective too (I bought a project car...) what the HVAC servo is seeing is an infinite resistance, which corresponds to very cold outside temperature, hence forcing to heat all the time. With the article that wallys suggested, you should be able to pin-point the culprit and find this temperature sensor. If you need more help, let me know... I'm working on this issue on my car these days...

Jeff

sfierle

Jeff, thanks. I plan to look at it this weekend. I got Wally's write up on the system. I never had to work of a climate control system yet, this will be a challenge for me. The a/c worked before, but was at full cold temperature no adjustment on the dash affected the temp, now full heat with occasional a/c. Wish me luck.

Steve