Mute9937

I just finished the replacement of the heater core. when i finished, there is no cool air blowing when i turn the switch to cold. I still have not recharged the ac since disconnecting them but i have not used it either. my lower vent also does not blow out air. Both the lower vent and the cool air worked before i replaced the core....what can i do to fix this?

99ZombieSport

What year is it?

MtnHermit

How about a 1999?

MtnHermit

Two things come to mind:

1. There's a mechanical valve the controls the hot water to the heater core, did you connect the cable from the temperature control to the valve?
2. The blend door is vacuum controlled, is the vacuum line connected? If not, the default is defrost only.

Mute9937

It is a 99, i did connect the vacuum line and i check to see if the actuator moved freely and they all do. I did not see a cable though...where is that at?

CCKen

OP: Maybe you should get your AC serviced then see if you get cool air.

The floor door actuator vacuum tube may not be hooked up to the actuator.

Mute9937

i will check to see if the line is disconnected, it did not appear to be but maybe i over looked it.
I was wondering if charging the ac would change it. i just did not want to if i had to tear it apart again.

CCKen

Before doing anything else, check the operation of the Blend-Air Door motor/actuator (See pic below).

Position yourself in the passenger footwell so you can look up to the bottom of the HVAC Unit, near the passenger foot air outlet, to get a clear view of the Blend-Air Door actuator.

Verify the electrical connector is securely attached to the motor.

With the ignition key to RUN, engine not started, turn the Temp Control **** from full Red to Full Blue, and back. You should be able to see the motor intermediate drive shaft move from stop to stop (90 degrees) smoothly and without hesitation.

If the shaft is not turning, remove the mounting bracket and motor assembly and try the above test. If it does not turn, the motor may be shot, but try the below test. If it does turn the Blend-Air Door may be jammed. Try turning the door shaft with your fingers. It should be able to turn, with some resistance. If it seems stuck, try turning the shaft with pliers. If still stiff or stuck, the HVAC unit was not reassembled properly.

Mute9937

thank you, i will try that

Mute9937

can a bad resistor effect any off that operation?
my resistor blew also but will be replacing it today

Mute9937

I checked the shaft, i was not able to see it rotate because of lack lighting but i could feel it turn with my finger on it. The shaft did not seem to get a full 90 degrees rotation though...i would guess that its partially restricted somewhere? whats odd, even with the rotation it does have, it does not really change temp still.

PocketsEmpty

Probably a blend door or vacuum issue as CCKen wonderfully laid out above. I saw someone mention the heater control valve...which your 99 does not have. Those are only found on pre-97 XJ's.

CCKen

Get a flashlight.

Refer to the above post.

Remove the actuator/motor assembly (3 fasteners) and see if the motor does rotate 90 degrees in both directions. You can mark the intermediate drive shaft and the motor body with a pencil or felt marker as reference points to see what rotation you are getting.

See if you can turn the Blend-Air Door shaft by hand, and/or with pliers, with the motor removed. Mark the shaft and the HVAC Unit, as above, to see what degrees of movement the shaft has...if any.

CCKen

Is this after you changed the blower resistor block? Or haven't you gotten to that yet?

Mute9937

this is after changing the resistor block...when i did the test yesterday, i passed over the part removing the motor, i will remove it and then test the door.