my friend has a 97 with auto climate (they all have auto climate right) anyways sometimes when the car is completely warmed up and he is idling with the temp set at 85 it is blowing cold air and other times its hot, same with when he is driving it sometimes blows cold and sometimes hot, any ideas? i hope its not the heater core, dont want to replace that for him if possible, or could the auto climate control be bad?

thanks

 

Tell him to test what the heat does when the engine is at a higher RPM. Usually if you have low coolant or a small block in the radiator the extra engine speed helps the water pump move the coolant past the block, or with low coolant the higher RPM helps the water pump pull coolant instead of water.

Also you can look at the coolant temp gauge if that fluctuates a lot with the engine warm it could mean the same thing.

If it's a blocked heater core it might need to be replaced

 

What he said, check your coolant level.

 

he was a little low on coolant we also replaced the thermostat, housing and it blows hot like a mother now

thanks!