Chrysler Repair: 1990 LaBaron heater core replacement, heater core replacement, heater cores

Question
I am having problems getting any heat from my 90 LaBaron convertible. I also have vibration coming from the fan. Could you get me started on removel of both componants. I have pulled heater cores before, but just cant see where to start. The car has a 3.0 engine with air

Answer
Hi Arvid,
I have the procedure for taking out the A/C-heater unit for the '89 model year but it is about 30 steps. I could xerox and snail mail you the procedure. I am wondering though whether you might not want to try and flush the system to see if the problem might not be a build up of crud in the core, or also whether the heater by-pass valve in the engine compartment might be stuck in the open position so that the hot water is not getting to the core. If you look at the hoses that go to and come from the heater (passing thru the firewall) on the engine compartment side, I believe you will find there to be a vacuum operated valve between those two hoses which if closed will cause the water to go as it is intended to the heater and return therefrom, but if opened will short cut the heater. That valve is only open when you have the unit set on Max A/C, otherwise it is closed. So see if the valve changes configuration when you go from Max A/C to heat positions. You might have a stuck valve or a cracked vacuum supply line to the valve. The last possibility is that the blend air door is not moving properly and thus not directing all the air over the heater core when you are calling for heat.
By the way, this is not the ATC (automatic temp control) type of heater system is it (with digital readout controls)?
That unit also has a self diagnostic system that I can tell you about if that is your unit.
Roland