Heater core I have a 1990 grand marquis and i need to replace my heater core but i can't find it any help would be appreciated

Here's a link on replacing your heater core. GET 25 GIFT CARD FOR EVERY 100 SPENT ON ONLINE SHIP TO HOME ORDERS Here's a new heater core. http://www.autozone.com/cooling-heating-and-climate-control/heater-core/spectra-premium-heater-core/mercury/grand-marquis/1977/8-cylinders-a-7-5l-4bl-ohv/491780_0_0

Is the air temperature control blend door working correctly check that and then also check to see if the cars engine is reaching proper temperature, you may have a stuck open thermostat.

This may be one of those where the entire dash has to come out to do the heater core.
But you only want to replace the core if it is plugged, or leaking. There is an easy way to tell if it is plugged: with the engine at normal operating temperature, and the control valve open so coolant will circulate, now feel both heater hoses. If core is blocked, only one hose will be hot. If core is circulating correctly, both hoses will be hot. If they are, you don't need to change out the core. One of your vacuum actuated doors is the problem, the blend door that lets air from the blower motor pass over and around the heater core.

Either your heater control valve is not properly operating or your heater core is clogged. Locate the heater control valve under the hood, should be close to firewall on heater hose, have someone adjust temperature from hot to cold and see if you can see the heater control valve operating if so replace the heater core, if its not doing anything replace it(heater control valve).

could be heater control or plugged heater core.. heater core could be cleaned out by unhooking heater hoses and running water through or a radiator flush.. if its your valve youll need to replace..

there are some on the ends to were the door closes on the dash

It's time consuming. you have to drop the whole dashboard and steering colum in order to get to the heater core. In a scale of 1-10 with 10 being the hardest, i say it's an 8.

advance has a brochure that will help or you can buy a hayes or chilton repair manual from their and it will give you step by step instructions with illistrations.

about $1200 US, this requires the dash be pulled out, about 12 hours of labor.

it is usually in line in the heater hose from the block to the heater core. it looks like a mushrom with a linkage on it.