87 heater/defroster/fan problem

[M1Garandfan]

Hi,

My 87 Grand heater/defroster is malfunctioning. It makes no difference whether I select heat or defrost. Nothing comes from either vent (lower or upper) I can hear the fan running, more like growling. If this were my 78 I'd check the vacuum lines. Any hints for this problem? :confused:

[Michael]

Yes check your vaccum lines. I did this on mine
last week. Check to make sure the vaccum canister on the firewall is allowing vaccum through too. The black ball. I had to hook mine up direct to make mine work. What is happening you are not getting vaccum to the switch inside the cab to open the heater door behind the heater core. Since everything apears not to be working.
I would guess for sure you have no vaccum getting inside your rig or the main line is pinched. Otherwise some of it would work. Good luck.

[M1Garandfan]

Is the switch for the heater/defroster behind the glovebox?

[M1Garandfan]

bttt

[Michael]

The main vaccum line runs from the firewall to the connector vaccum connector behind the ac/heat controller.

You have to remove the black dash trim...that goes around the gauges to the radio. Remove the phillips head screws to the ac/heat control. And pull it towards you. The vaccum lines are all together snapped in the back. As far as tracking the main line. I could see mine from under the dash. It would help to remove the glove box and radio to see everything. Good luck