heater blows cold air

[mike125]

I have a 2003 6.0 f350. In the winter (I live in Michigan) my heater does not blow hot air. I would call it luke warm at best. The faster that I go the warmer it is. IE: its warmer at 75mph than at a light at idle. Someone recommended that I install a cover over the radiator on the grill for winter. Could there be another problem. The truck is stock. I am new to this site any info would be great.

[symbols]

That sounds like a blend door issue to me

[mike125]

Thanks for the info, ill check into it.

[POWERED SPARKLESS]

Check you level, if it just a little low pressure doesn't build right so you don't get hot air untill higher RPM's. If its low ONLY fill it with distilled water or the Ford Premium Gold coolant.

[VeeDubTDI]

Definitely not normal. Mine blows hot at any speed once it warms up, even in the brisk Michigan winters.

[fordmasterdieseltech]

hows your coolant level? does the truck reach operating temp like it should? what is tthe repair history on the truck?

[k2davis1]

I had same prob earlier this winter. Dont run to the ford dealer just yet cause they will prolly blame it on the heater core and kindly offer to replace it for 500 bucks. You might have some air in the system, try to burp it by letting it idle with the cap off degas bottle for 10-15 mins. That worked for me but it also means you prolly have bigger probs like head gaskets. Hope this helps.

[dannyboy950]

Have you removed the thermostat at any time. This will also cause it to build heat slowly.
Altho it probably is a blend door issue.

[fordmasterdieseltech]

sounds like you have air trapped in the system, now the cause of the trapped air may or may not be caused by head gaskets. if you can pull a vacumm on the system or allow it to idle cap off for 15-20 mins and see if it gets any better. you may also have a water pump issue. the 6.0's are known for the impeller coming apart from the shaft and not cirrulating any coolant.

[kingranch89]

mine did this when the head gaskets were bad