I have read through all 24 pages of pre1997, and just want to make sure I have this right. My heater blows fine, goes through all positions ie. defrost, floor, vent but it blows luke warm/cool air not cold tho. I changed out the thermostat (nipple out) about 6 months ago and heater core/flushed the system 09/08 and replaced radiator cap. I made a trip from Mississippi to Minnesota towing a 16ft trailer and furniture. Everything fine as far as engine running doesn't overheat, the needle stays straight up around the R which was the norm prior to the replacement of parts. I feel that I have air in the system. By the way the heater hoses do get hot. I feel water going through the input to the heater but very little in the return. I am going to run it at idle with the cap off and hopefully it will warm up enough to open the thermostat, I feel there is air and probably low on coolant. Am I going in the right direction? Thanks in advance!

 

By the way I want to say that this is a great way to learn about my truck, after reading the posts in the past I have already fixed a couple of probs.

 

Your hot/cold control may not be moving your diverter all the way to the heat position (Garbage, pencils and so on in the way of it going all the way).
Or your heater hoses may be hooked up backwards.

If not one of those two then the heater core is plugged and needs to be replaced or taken out and cleaned.

 

Thanks subford, I will check those two items

 

i am pretty sure the 92 up trucks are vacuum operated doors in the heater box you might have a weak vacuum or a leak

 

At all Ford trucks 96 an older have a cable operated temp control (blend door). The blend door on 97 or newer is electrically operated.