1. Home
  2. Chevrolet 4x4 Trucks
  3. 88 S15 Jimmy heater question

88 S15 Jimmy heater question

I just picked up an 88 S15 Jimmy from a family member who's owned it since new. I noticed tonite the heater blows lots of hot air, but the vent adjustment (from defrost to floor) doesn't work at all.

Its one of the vaccuum based units, and nothing seems to happen when you move the slider - adjusting the heat setting works great, just not the vents...

Now its stuck sort of between the floor and defrost, with the majority going to the floor. In winter you can see the dilemma I have :) Its not important to me that the vent settings work again, but i'm more interested in finding a manual way to force the diverter door over so that it directs ALL the heat to the defrost.

Any insight on the easiest way to do this? Or is there a known/easy fix for getting the vaccuum driven divertor door to work again? Either way will work. Is there an external lever that a vacuum actuator moves that I can just disconnect and move manually?

I had this issue in my 91 K1500 with cable driven divertor - there was slop in the lever so if you put it all the way to vent, it got "stuck" there and had to get up underneath and manually push it back.

Your thoughts on how to get the most heat up on the dash as possible are appreciated!

b
Reply to
Hamilton Audio
Loading thread data ...

It seems I answered my own question. It turns out there's a small metal lever on the bottom of the airbox that was spring loaded to the "floor" position. I merely undid the spring and it jumped back to defrost and with the aid of a large rag stuffed inside from underneath, the defrost blows wicked now...

b

Reply to
Hamilton Audio

If you want an adjustable solution, in my experience with GM's air coming from the defrost and floor vents is a bad control unit. It has a plastic vacuum select disc with a rubber gasket. When that tiny, special little gasket wears out, it bleeds vacuum and won't move the directional doors. Listen for hissing from the dashboard control, esp. in Off and Defrost positions to diagnose. Really no good solutions that I know of. I've used junk yard parts, but they are normally dried out too, and its very hard to reassemble.

Jeff

Reply to
jeff in Atl

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.