I don''t know of any diagrams, but if I run across some, I''ll post them. Someone else may know more. I''m one of those remove things until I find it and put it all back together after I fix it people.

CHances are the core is plugged... They seemed to have some trouble with this.. (Old as 96 and new as 03).. And both heater hoses may still feel hot even though no coolant is flowing through the heater core since there is a bypass between them.. (I''''ve seen people clamp the bypass hose shut to try force some cooling tough) I blame the damn extended life antifreeze, but that''''''''s another thread another time... There is the chance though that the blend door actuator (or something in it''s circuit) has taken a poo... The doors that direct the air (to the vents, floor or defrost) are vacoum, but the temp control is electronic.. Unfortunatly in this cold weather it''s hard to test the blend door but Ford''s diag procedure starts out setting the HVAC to Max A/C with the knob the whole way on cold.. THen turn it to hot and see if the temp changes at all..


With a cloggged heater core what I have done on my 97 Sable, and a few other peoples cars (and this is not probably recomended, but I have had it fix the heat or at least paritally unclog it for some heat)..


Disconnect both hoses from the heater core... You may want to go get a short length of 5/8" heater hose and put on the one spoutof the heater core to make this easier. Step one is to blow all the liquid you can outta the core.. (Air compressor GENTLY, or good ole human power) Then fill the heater core as full as you can with draino (or equivelent) Muratic acid (used to clean hot water and steam heating systems) works even better.. Let this sit for a few hours to render...


After a few hours flush the heater core out THOROUGHLY with water (garden hose connected to the heater core works great) you don;t want the drain cleaner in your engine.. Good idea to flush the rest of your cooling system while you''''''''re at it since it''''''''s probably gunky as well..


Re connect the heater hoses and see what happens.. Worst case scenarios??? THe acid eats a hole in the heater core and it will need replaced, it does nothing and the heater core needs replaced.. Either way it can be worth a shot as these heater cores are not cheap/easy to replace...Edited by: maxfax3

This is just a suggestion, I have a 1989Mercury Granmarquis with the same problem. The way i solve my problem was todisconnect the vacuum hose that goes to the actuator valve and the heat was back. Now in the summertime connect the hose back and i have ac. So i hope this works for you as it did for me.

Hey Max, if the acid eats through the core, then won''t it eat through the dash, other HVAC components, the rug, etc.? And if it doesn''t, won''t you be circulating toxic acid fumes throughout the cabin? I think that is probably not he best advice to be spreading around.

The muratic acid that the average individual can purchase at a hardware isn;t stroung enough to instantly disolve the heater core.. Drain cleaner is somewhat less potenet (do not mix drain cleaner with any acid though, that''ll make some nasty fumes and such!)However if there is a weak spot inthe core andit is under pressurefrom the cooling system it could spring a leak... Usually the equivelant of a pin hole...


Same principal as flushing all the crap out of a cooling system only to have things start to leak (freeze plugs, radiators, heater cores, intake gaskets, ect) The dirt and crud that was in there was keeping the hole plugged....


IF you are usingacid strong enough to disolve an aluminum heater core in a matter of an hour it probaby wasn''t obtained legally.Edited by: maxfax3