1996 Riviera idle and heat Problems

So I just picked up a 96 Riviera s/c with 60K miles on it. It has an idol problem. It feels like a misfire when in the car but when you pop the hood it has a sporadic rattle noise. The car doesnt make the noise while driving tho.

Also I am only getting hot air out of the drivers side vents, even if the a/c is on cold.

Any help would be great!

Thanks!

So I just picked up a 96 Riviera s/c with 60K miles on it. It has an idol problem. It feels like a misfire when in the car but when you pop the hood it has a sporadic rattle noise. The car doesn't make the noise while driving tho. Also I am only getting hot air out of the drivers side vents, even if the a/c is on cold. Any help would be great!

Not sure about the idle (tho shall not have false idols) but I'm getting left/right heat imbalance under certain conditions too, such as cold morning on the Interstate in the month of March.


-Ed

Any codes?

Check for vac leak at upper plenum gasket, by spraying carb cleaner and listening for a change in idle....

With A/C off, dual off, use vent position and command full hot and then full cold.....is temp same on both side? If no, then posibble temp actuator problem......if ok, then possibly low on freon....

It would be very rare to have a UIM gasket leak on the L67 S/C engine. Check all vacuum fittings & hose connections. Where exactly is the "sporadic rattle noise" coming from & what does it sound like? Be as specific as possible; does it sound like someone hitting a piece of metal with a hammer, or shaking marbles in a can -- etc?

Hotz, ran into this several times....caused an Idle problem.....spraying carb cleaner between upper plenum and top of lower intake, caused idle to change......removing the upper plenum/SC'er, found the gasket broken....this gasket is nothing like the one for a regularly aspirated 3.8....