No heat or defrost in 2002 grand marquis. Thermostat problem?

Thanks, how much would that cost to fix and where are you located? OK thank you

Proper diagnostics should be administered first, but if it is the heater control valve, the cost: parts, labor, coolant, tax is about $238. We are located in South Sacramento. Off 99/Fruitridge Rd at 5681 Franklin Blvd, Ste C.

please expand on bad heater control valve, location and cost? thank you Thank you for youre prompt reply I did purchase a thermostat and should I try that first?