86 suburban heat failing...

[reliant2]

86 suburban 350 4bbl 2wd....the heat is not working very well at all.....the defroster works great, the heat out of the floor vents has become way weak....i know that a few years ago there was a bit of an anti-freeze drip coming from somewhere under the dash on the passenger side, but i've had the truck for 3 years now, and it's never dripped again...

any thoughts? is the heater core dying, is something clogged?

thanks

[corning_d3]

Did you have a drip with the air on or not? If it was with the air on, it was more likely to be a stopped up condenser drain tube. If it was without the air on, I'd say it's time for a new heater core, if none of the heater hoses are clogged. Another thing to check would be the thermostat. A good way to check both is to warm up the vehicle and grasp the heater hoses with the engine running. If they are hot, the thermostat is fine, but the heater core may be clogged. If they are just warm, then the thermostat is hanging open, and needs replacing with a good quality, 180 or 195 degree thermostat, depending on the outdoor temp. where you live.

[777stickman]

Originally Posted by reliant2

86 suburban 350 4bbl 2wd....the heat is not working very well at all.....the defroster works great, the heat out of the floor vents has become way weak....i know that a few years ago there was a bit of an anti-freeze drip coming from somewhere under the dash on the passenger side, but i've had the truck for 3 years now, and it's never dripped again...

any thoughts? is the heater core dying, is something clogged?

thanks

Reliant2: ?'s. Is the air out of the defrosters HOT and can you control the heat out of the defroster vents? If the answer is yes to both then it would seem the heater core is OK and the problem is in the distribution of the heated air. I don't know if the '86 had electronic or manual controls for the air distribution. If you've got HOT air coming from the defroster vents and low air flow from the floor vents then you need to look at the distribution system, doors, cables, ducts etc. Let us know!

[Old Dave]

My 86 Suburban was vacuum controlled. Check behind the glove compartment. There is a clip on a door that it bad about breaking and won't allow a vacuum operated door to open or close. (I forget which it is)