My heat in my 2000 GMC Jimmy doesn't work....... How do I fix it?

[Fanatic111689]

I got a 2000 GMC Jimmy. Last year at about this time there was a bad snow storm and my vehicle was stuck outside in it. After that day the heat didn't work at all for a few weeks... Then one day it started to work again once the car was on the road for a mile or two after I start it.... Now it's the same situation, I get heat but it takes a couple miles of being on the road and then turning it on for it to work. And even when it works only level 1,2,3 works.... 4 doesn't at all. I was just wondering what could the problem be? It not like no heat comes at all, it just takes forever though and even then it's not all to hot, and only the vents and head-heat...... No floor heat at all! Please help!

 

[Molson02536]

As for the speed, sounds like the switch has gone bad and that is a simple fix buy replacing it with a new one. Auto Zone has that part and takes about 15 min to replace. As for getting heat, your going to have to replace the Thermostat and if the engine coolant have not been replaced every 5 years or 100,000 miles, the Dex-cool may have crystallized through out your cooling system like the heater core causing poor coolant flow. There is a TSB to replace thermostat and flush out the cooling system with Preston radiator flush and refill with a mixture of 50/50 water/Dex-cool. Not to much water will freeze causing the engine block and intake manifold to crack, to much Dex-cool will gel up causing coolant flow to be restricted throughout your engine and heater core. As for the no heat, inspect the switch that control the vents the same time you work on the blower speed switch. The vent selector is a vacuum valve and it's know to have the vacuum lines to have a bad seal or broken vacuum lines, Inspect, repair or replace any parts that are worn.Good luck and hope this helps.