New 300SD (1980) AC works now, no heat
 

Just purchased a 1980 300SD with about 175,000 miles on odo. Engine about 100,000 old and trans replaced about 6 months ago. When I got it, A/C not working, but have replaced compressor and servo (ouch!!) and now A/C works but no heat. BTW, car won't stop running unless climate control :confused: fan is on. Any ideas on getting the heat working?

Thanks

Maybe a vacuum leak. Check all connection including behind glove box and under dash on passenger side.