First Start Discoveries - Tach and Climate Control Issues

[Bulldog9]

Finally got the mechanicals done and did the first start of my 944S2 yesterday. (See I am a Wet Head Thread).

During the shakedown drive, I have discovered that the Tach does not work, and neither do most of the Climate Control functions. The Mechanical Fan Speed switch works, but that is it. Surprisingly, the odometer does work.

I'm busy reading the Tach threads and will pull the gauge cluster to clean up connections, but don't know what else to check or test. I thumped the Dash and the dial jumps so it is not frozen. Most of the threads on this are old, so any advice would be helpful.

On the Climate Control, I think the unit is fried. When I first rescued it last September, on connecting the battery, a bunch of smoke and popping came out of the slider vents, and the electrical smell still stinks. What's the best/most reasonable source for these?

[Arizona_928]

You’re going to give the multimeter a workout.

Runs but no tach… usually it’s no tach = no run. You know the speed and reference sensors are working to the puter’… signal to the tach or the tach itself. Either way. You’re pulling apart your dash.

As for the climate control. Since some of it works, i would say the fuse is good… Then check power to switch itself. Prolly a bad switch tbh. Also could have fried your wiring. Pull and inspect wiring and switches.

[djnolan]

Climate control: Clock and Temperature Control Unit Removal and Replacement

HVAC internals: http://www.clarks-garage.com/shop-manual/hvac-02.htm

Gauges, etc: Sensors and Gauges - Information, Troubleshooting, and Testing

[Jfrahm]

I had one of the VDO tachs die in one of my cars, bought another used cluster and swapped tachs.

[Bulldog9]

Originally Posted by Arizona_928

You’re going to give the multimeter a workout.

Runs but no tach… usually it’s no tach = no run. You know the speed and reference sensors are working to the puter’… signal to the tach or the tach itself. Either way. You’re pulling apart your dash.

As for the climate control. Since some of it works, i would say the fuse is good… Then check power to switch itself. Prolly a bad switch tbh. Also could have fried your wiring. Pull and inspect wiring and switches.

Thanks. Yes I ran down all the Climate Control tests, motors, sensors, etc, from the charts available on Rennlist. Everything checked OK including the movement of flaps and motors, no cooked wires to indicate a short of any kind, and good resistance numbers on sensors. Confirmed the AC Compressor clutch is not shorted, and 7.5 amp fuse intact and unblown. On examining the unit, I think a capacitor crapped the bed and fried and burned out. There was one other that was also swollen.

As for the Tack, everything works and checks out. I think the tach itself just died. I talked to the prior owner and he said that one day it just stopped mid drive. He never had it looked at.

I hate the 'throw parts at it' but with all the known problems eliminated, it leaves the failure of the unit itself.

[Bulldog9]

Originally Posted by djnolan

Climate control: Clock and Temperature Control Unit Removal and Replacement

HVAC internals: Air Conditioning Troubleshooting and Repair

Gauges, etc: Sensors and Gauges - Information, Troubleshooting, and Testing

Thanks. I think I have checked those out, but will double check again. Clarks Garage is quite the resource.

I already swapped out the clock and have tested all the other gauges and sensors. Everything works as it should other than the Tach and Climate control. Even the Odometer. I may change out the gear while I have it all apart. I will definitely upgrade the backlights (well frontlights) for the gauge cluster. My goal is to get as close to a concours car as possible with the exception of the Fuchs Wheels, but that is an easy bolt on/off.

[Bulldog9]

Burned out Climate Control. Only the Fan Speed switch worked, though when the AC was pressed it did trigger the cooling fans.

[Arizona_928]

How’s your writing and connector?

[Bulldog9]

Originally Posted by Arizona_928

How’s your writing and connector?

I was worried about that too, but they are perfect.

[Bulldog9]

**Update - I tested all the controllers and sensors from the charts found over in Rennlist and all checked out. Ordered a new climate unit and charged with R134 (had already been converted) put it in, and EVERYTHING works!