: 1979 HVAC problems

02-02-07, 10:41 PM
I seem to have a problem with my HVAC. The only time the blower motor works is when i put the climate control on defroster. All other settings dont run the blower motor at all. I allready replaced the blower motor. I can hear a click coming from the fuse panel when i put the defrosters on, but no click for all other settings. Im thinking the climate control is bad but i was hoping it was gonna be an easier fix than that. Please Help!!!!!! What should i do???:bonkers:

02-03-07, 09:06 AM
Hey could it possibly be my blower resistor??? I pulled it out and it was all rusted. Im not sure if this would cause it to malfunction or not. There are no moving parts so how can this thing go bad???

The Ape Man
02-03-07, 11:02 AM
Blower resistor is bypassed on high setting so it can be eliminated from a no blower fault. Don't try to run the system without the resistor installed in the airstream where it belongs or it could become damaged.

'79's had an issue with the plug on the rear of the dash control panel melting. The teminals inside were aluminum and ran hot. After time they would get loose and run even hotter. This would melt the plug. Look there. Another place to look is that relay which you hear clicking. Somethime the contacts inside just cook themselves to death. Also the panel which the relay plugs into can melt for the same reason as mentioned above. Same thing happens to power seats on these cars.

02-03-07, 02:57 PM
Hey thanks. Ill check those plugs out in the back of the control. Hopefully thats what it is.

02-04-07, 04:19 PM
79s also have a temp sensor one one of the cylinder heads ( drivers side I think) that is designed to keep the blower off until the head reaches operation temp. They have been known to go bad and cause your symptoms.

The Ape Man
02-04-07, 10:18 PM
Yup, That's right. I forgot about that one. Spade terminal in the rear corner of the cylinder head. IIRC passenger side. Ground it to see if the blower starts again.

02-10-07, 08:37 AM
I'm having a similar problem with my '79 limousine. The blower runs only on DEF. I am checking the sensor later today, but I have another question for you guys...Is it normal for the heat to be on when DEF is selected? When the DEF is on, the blower is on full and all I get is hot air. If I move to any other position, the blower turns off, but I am still getting a flow of hot air through the floor and a/c vents if the car is moving. Cabin gets a little too warm! Mark