May be a vacuum leak under hood or dash That model has a self-diagnosing climate control system--Unfortunately I don't remember the code or sequence I found same at library or perhaps dealer will help
Do you already have the old one out?
Tie the 2 water lines that run to heater core together
how do i change the heater core in a 1990 Eddie Bauer
If you have never done this before then I would recommend that you get a repair manual because there are over 40 steps to do this job and its very complex............
BIG JOB Get a manual on your car from the parts store and it wil have pictures .
Where is the starter on a 1990 lincoln mark 7
This process could take up to 3 hours. The Heater core is best flushed if you are having problems with flow. Is this an option? F. Garay
That job is known to be a scourge among mechanics. Pay someone to do it, trust me.
In order to change the heater core on an 90 ls400 you have to remove the entire dash pad and cross bar to be able to remove the heater core box. This is a job for and experienced LEXUS technician www.lextechautomotivellc.com
the heater controls are run on engine vacuum. When a engine is accelerating it has a drop in vacuum. There is a one way check valve that keep vacuum in the heater circuit that has gone bad. You could have it fixed or you can deal with it, its not that big of a deal
where is voltage regulator on 1990 lincoln town car
you dont!you just connect both the hoses together.and wear a gloves hat and a heavy jacket!