A/C hot sometimes, sometimes not?

Chris97K1500 · July 28, 2003

I drove my mom's '02 Trailblazer this past weekend. I love how smooth it drives! But anyway, the A/C blew hot air after I started it and drove a few minutes before I turned the A/C on. The air stayed hot, even after waiting over 10 minutes. I turned it off and back on, still blew hot air. Finally we get to the farm and I turned it off. Sat for about 10 minutes, then started it back up and drove around on the farm just checking the fences. The A/C blew cold air, very cold air. Never messed up on me the rest of the weekend. I told my dad and mom about this, they told me, yeah, it's done this once before about a month ago. But it hasn't acted up since. We're thinking it must be a bad switch or relay somewhere. Still under warranty, but I'd just like to know if this is a common thing on these vehicles? What's your thoughts on this? Thanks, Chris

bravada2002 · July 28, 2003

There's at least two TSB's on this issue that I know of and it's a common problem on edmunds TB forum.

Air Conditioning (A/C) Inoperative/Intermittent, A/C Blows Warm Air (Replace A/C Low Pressure Cycling Switch) #03-01-39-007 - 05/29/2003)

2002-2003 Chevrolet TrailBlazer, TrailBlazer EXT

2002-2003 GMC Envoy, Envoy XL

2002-2003 Oldsmobile Bravada

Condition:

Some customers may comment that the A/C system is intermittently inoperative or blows warm air.

Cause:

An intermittent inoperative (open) A/C low pressure cycling switch may be the cause. This is an intermittent condition and temperatures may play a critical role if the vehicle is in the failed mode or operating as designed.

Correction:

Make a service appointment

OR

HVAC System Inoperative for a Drive Cycle, Poor HVAC System Performance in High Ambient Temperatures (Update HVAC Control Module Software) #02-01-39-005 - (09/23/2002)

2002-2003 Chevrolet TrailBlazer, TrailBlazer EXT

2002-2003 GMC Envoy, Envoy XL

2002-2003 Oldsmobile Bravada

Condition:

Some customers may comment about no cold air from the heating, ventilation and air conditioning (HVAC) system during a drive cycle. This concern may occur at any time during the drive cycle and at any temperature setting. The HVAC system operation returns to normal after the vehicle has been keyed to off and restarted. This concern is intermittent and most likely to occur on hot days. This concern may be found on vehicles equipped with manual (CJ2) and automatic (CJ3) HVAC systems. Other customers may comment about poor HVAC system performance in high ambient temperature conditions. This concern may be present in automatic (CJ2) HVAC systems only. An HVAC control module software update was put into all production vehicles beginning in September 2002. Vehicles built in September 2002 and earlier may need this software update.

Correction:

Make a service appointment