Hello! I am experiencing a problem with the heater in my '98 F150. The heat will come on for a few minutes but will then blow cold air. This happens even if I wait for the temperature gauge to be normal before turning the heater on.

I've recently been told there is a crack in my engine. Could this be causing the heater problem? I want to make sure I know exactly what is going on before I take it in so I don't end up in the poor house.

Thank you for your help!

 

The coolant system including the heater core and related hoses have to maintain a constant level of coolant. If the coolant leaks out, air will enter the heater hoses and core resulting in an intermittent heater operation.

Another possibility is that of a plugged or restricted heater core. Without a good flow of coolant thru the core, the fan air will cool the non flowing liguid and thus you will feel cold air from the registers. Make sure both hoses have an even temperature between them, this signifies good flow.

Why were you told the engine is cracked?

 

I had a mechanic take a look at my truck because it was shaking when I turned it on. He told me that there was no oil in it (yes...I get regular oil changes) and that it possibly meant that there was a crack in the engine or in one of the heads.

A few weeks ago I noticed a puddle underneath the truck (which I haven't seen before) and a friend of the family replaced my water pump. The heater worked for a while after that, but it has since stopped.

 

I think your just low on coolant. Mabey you didn't refill it all the way after the water pump change.