I have 89&86 xjs on the 89 the heater-evap door not working anybody know vac or elec opration which side for door i guess pass. have heat all the time also only def blower no vent or floor.

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Possibly vacuum leaks in the system. Also, possibly AC Amplifier. See if you have vacuum at the hot water valve located on the firewall. No vacuum makes it stay open, letting hot water into the matrix. When vacuum is applied, it should close, keeping hot water out. The valve itself could be frozen open. You can still get the original valves, or plastic ones that work just as well, for a lot less money. Report back, maybe we can go from there if its something else. Keith.

 

Vacuum leak yes, amplifier no on an '89. There are two vacuum solenoids on each side of the climate control, operated by the climate control ECU. They fail regularly. I can't recall at the moment, but I think the defrost solenoid is on the LH side, it's behind the console side panel. Look for green plastic hoses, that is the defroster flap vacuum supply.

 

i just had a 89 dash out. i think the defrost solenoidis on the left side.