mattbarron94

My heater doesn't work, and it hasn't worked since I inherited the truck. Things I can tell you, cooling system has been flushed very recently and properly. Both hoses running to and from the heater run very hot. My engine temp never goes above halfway on the temp gauge. There are no leaks in my heater core. My ac runs ice old.

If anyone could help me diagnose and fix the problem that would be great. Winter is coming and I'm driving a lot more this winter so I can't just "deal" or "put up" with the cold like I usually do.

Thanks guys.

fltdriver

Check to make sure the blend door is working properly as well as the temp selector on the climate control center. If both are functioning the heater core may be covered in dust/debris preventing air from flowing across the fins.

My guess would be you temp selector isn't going to the heat setting, I believe it's controlled by a wire that slides a lever one way for cold then the other for hot. Check for obstructions and lube it.

fetasigma

flush the core seperate from the rest of the system using compressed air and or clr after you have checked the above

dkenny9

My 96 300 is having the same issue, but it was like that prior to replacing the water pump and t'stat. I'm heading out to double-check the heater hose temps, the last time I checked they were both the same temp (hot) so I don't believe that my issue is heater core blockage or restriction but most likely the blend door.

fltdriver

Have someone adjust the climate control from vent to ac then to off, floor the defrost, you should see the lever on the BDA move with the different selections.

dkenny9

It was summer when I last checked the temp on the heater hoses, now that it is 30~something degrees I can notice the difference. The top hose from the thermostat housing to the core is noticeably hotter than the return hose.
Looks like I have flush work in my future. I plan on using a CLR type product to clear out as much of the corrosion as possible.

fltdriver

I would recommend pulling both heater hoses off of the water pump, flushing for a few minutes with garden hose to get rid of any major blockages. Install a flush kit ($4 @ walmart), replace hoses, use something like Prestone's radiator flush chemical in your coolant for a couple of days, then do another flush of the entire system.

Or... get a new heater core for ~$20-$30, but would still flush the system with chemical and install flush kit before you replace the core.

dkenny9

Thanks for the advice FLTDriver. If I was doing this job during warmer weather I would have tried to save the core by flushing and purging the system repeatedly. Once I considered the time of year (cold!) and want good reliable heat NOW, and the price of a new unit being $25.-, and this being a fairly simple job, I decided to replace it. I just finished the final fluid change tonight after swapping out the core. I flushed and replaced the entire system last summer so the coolant was in good condition. The damage had been done by the previous owner due to neglect, it was severely restricted. All is well now.
Thanks to all for the advice.