1990 Volkswagen Jetta Q&A
1990 Volkswagen Jetta Question: Heater does not work. Blows cold air.
It's hard to know how much a repair will cost if you don't know what the problem is. So, there are a few possibilities. Thermostat stuck open, Heater core plugged, heater valve inoperative, heater valve controls inoperative. Start by looking at the heater valve, and I believe it is controlled with a cable. Make sure the cable is operating the valve when you move the temperature control lever. If this is OK, let me know and I can direct you further. Good Luck! - Bret Bodas
Being it's an 85 and I had one as well...I'll bet the insulation has deteriorated off the flap door. Do you have foam flying outta yoru vents? Or remnants of it on the interior floor? If it's yes...that's your answer. The fix?...1 roll of duct tape, removal of knee dash, pop open the core cage an voila...you'll see the flap...tape it up ON BOTH SIDES OF FLAP, button it all back up...and HOT HOT HEAT! All VWs with some age on'em eventually have this problem...don't know why in the hell VW did the flaps this way...hop ethis helps! - Visitor