i just replaced the thermostat in a 91 ford tempo gl and still no heat just blows cold???

heater core?

I was told there is a switch under dash that might be the problem anyone know where it might be located?

with new thermostat put in it overheated twice within 60 miles could it be a faulty thermostat? gonna try putting old one back in and see what happens

i also have a Lincoln town car is that real enough for you? lol just tryin to come up with a quick solution for the tempo

I've had to flush plenty of heater cores months after people have used a stop-leak. If it's overheating after replacing the thermostat, it's in backward, low on coolant or the fan doesn't work. There are no switches under the dash neither is there a water control valve = coolant flows through the heater core at all times. There is also the possibility of a worn or loose water pump impeller that's not circulating coolant.

I forgot about the good old "rat's nest in the heater plenum"

both hoses are hot, it was running below normal temp when I put new thermostat in and has been driven 100 plus miles sense it was put in n all the sudden just started overheating

Need pictures were is the thermostat on a 1992 ford tempo