it sounds like the heater is working, but to be sure, put your hand on the valve cover. if it's working you should not feel cold metal, but warm. if it is cold, and you don't have howling wind, it's not working. if you do have howling wind, put your hand on the actual block between the injectors should be pretty easy to feel. still cold? bad heater, or cord. get a VOM and measure the ohms of resistance between the two blades of the plug. post results.
John

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!