Hi I have a question about my 98 grand prix gt's heater. My heat only works on high and when it does work it only works for 10 minutes tops. It also makes a high pitch squeek sometimes and when it runs properly, after that 10 minutes, it starts making a funny noise and barely works. Sometimes when it doesnt work I have to hit my dashboard for it to turn on. Sometimes it doesnt help at all to hit the dashboard. What is wrong with it?