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87GrandWag
11-25-2003, 12:18 PM
My heater won't work on my 87 Grand Wagoneer. The heater core and blower motor are fine. I can put the selector in either of the 3 heat positions heater, heater defrost combo or defrost, but no air is coming out of them. Any input? It is kind of cold in Colorado at night.
J10/J20 Project
11-25-2003, 12:32 PM
Welcome, The only thing I can think of is there is something blocking the duct, or the blower motor is spinning, but some how the blower wheel isn't. The cable came off the bottom of the heat/cold slider. Have someone move it while looking at the heater valve in the engine compartment to see if there ios movement. Heater valve went south. Let me know if you need a hand free most night's.

Paul

[ November 25, 2003, 07:34 PM: Message edited by: J10/J20 Project ]
Michael
11-25-2003, 01:04 PM
Your controls are operated by vaccum. Same as mine. Check first if you have vaccum coming through the black ball (vaccum cannister) in the engine compartment on the firewall. If none is coming out. Dissconnect the two vaccum lines from the "ball" and connect them together. Then go in your waggy and start her up. See if it works then. If it does not make sure you have vaccum there. If you do then it must be internal on the back side of the temp control switch. Mine was the ball and a pinched vaccum line under the dash. Good luck. What is happening is the main heater door will not open until selected in the heat position. The other directional doors will open in the diffrent positions. Without main line vaccum...the main door will not open. Your blower will blow...but it is like hitting a brick wall. The main door is behind the heater core.
87GrandWag
11-25-2003, 01:43 PM
That worked. Is it ok to leave it bypassed? The little black ball had one of the plastic tips broken out of it.
AMX factor
11-25-2003, 03:08 PM
I removed my black vac ball altogether. I runt he heater vac directly off the intake. I also run the 4wd vac line off the intake direct.

Where in Litleton are you?
Michael
11-26-2003, 12:42 PM
Yeah I just bypassed it. The only problem I see technically is that if at full throttle. If you engine needs the vaccum there will not be any reserve for the heater system. Meaning... the door could possibly close. But would open as soon as you resume reqular throttle or vaccum conditions. That is what the canister does is stores vaccum for acessories like the heater. Other than that. Nothing. Leave it like it is. It works!!!!