Sounds like a case of a neglected, ghetto repaired car.
Glad you have a solution within the customer's budget to make the heating work.
I won't be surprised if the heater core is clogged either by a precipitate (improper coolant mix, hard water, etc.) or by a "magic" sealant (if they tried to fix a radiator leak in the past).
There is a lot of animosity on this forum about what mechanics charge us for car repairs, but we don't see what you guys have to deal with sometimes.
I don't think I'd like to work on cars like this one, no matter what they'll pay...
Last edited by Megalocnus; 12-06-2012 at 12:55 AM.