My AC and heat only work an the HIGH setting. Any ideas why and how to fix this??? My baby is a 2000 2DR 2x2 Blazer with manual ac/heat controls......I think.

 

By heat and A/C, you are really referring to the fan itself, correct?

If that is the case, then the most probable cause is the blower motor resistor block which is located on top of the HVAC housing under the hood.

 

I'm having this exact same problem also. The fan does work on level 1 or 2. If I switch it to level 3 or 4 it works. Once I get going, it will then sometimes work on level 1 and 2.

How much is this resistor?

Thanks,

Rick

 

ACDELCO Part # 1571991 {replaces 15652873 #15094285, 15652873} Blower Motor Resistor $12.05 - RockAuto.com

That part number is good for both the OPs 2000 and your 1999, C5Longhorn, with manual HVAC controls only.

 

Thanks Swartlkk,

Is it easy to diagnose whether its the relay or resistor? I've heard that if level 1 and 2 don't work it may be the relay. Either way, I'm happy to see that hopefully it won't be too expensive to repair.

Rick

 

Everything but high is controlled by the resistor. If high works, the relay is good.

 

Kyle,

You are a wealth of info. Thanks again for the tips.

 

Is it necessary to put the black cover piece that was cut out back on with black sillicone adhesive.

 

I wouldn't worry about it unless you cut it real clean and want to duct tape it-I usually don't. Jerry

 

My only concern was water and moisture. If that's not a problem, then I'm not putting it back on.

Rick