2000 Chevy S-10 w/ 4.6L V-6

Hey I have a Chevy S-10 with a temperamental heater issue. It was originally having A/C issues and after replacing pretty much everything it began to work and we aren’t sure what was the problem in the first place. I would like to avoid this issue when it comes to fixing the heater. The blower motor runs fantastically and the engine temp. gauge rises to normal operating temp. Any guidance would be greatly appreciated.


Poor College Student in Montana

originally having A/C issues and after replacing pretty much everything it began to work

If you could please elaborate on what was included in “everything” it surely would help. Did any of the replacements happen to involve parts in the interior? Any work on, for example, the blend door or its controls? (There’s a little door in the ductwork that controls what kind of treatment the incoming air gets - over the evaporator core for A/C or over the heater core for heat). Since the troubles involve both A/C and heat that’s my first guess.

Could you describe what the heater does when it’s being “temperamental”, as well as the issues you were having with the A/C?

All of the heater and A/C controls on these trucks are run by engine vacuum and you start getting leaks as these trucks age. If this truck is a 4x4 transmission fluid could be getting into the vacuum lines due to a faulty transfer case vacuum switch (apparently this part was redesigned to fix the problem).

Here are two links about this problem.

The A/C would refuse to work but the heater sill did and I still had temperature control. The coolant core was flushed twice, the A/C was discharged and recharged, all the rubber hosing was replaced, and to the best of my knowledge nothing was adjusted inside the cab.

This truck is only a 2x4, and while it could be a vaccum issue I still have a little control over the temperature. For example on a hot summer day I can turn the temperature dial and the air that is blowing will cool a little even when I don’t have the A/C engaged. Whereas when it comes to a cold morning the temperature dial has no effect on warming the temperature of the air entering the cab.