HVAC problems

[Jonny-K5]

when i turn the HVAC lever to defrost, the AC pump comes on. where should i check first? faulty unit in dash?

 

[Smitty]

when i turn the HVAC lever to defrost, the AC pump comes on. where should i check first? faulty unit in dash?

Sounds like it's working the way it was designed. The A/C takes the humidity out of the air and assists in the defogging process.

 

[1985_K5_Silverado]

Yep, that's the way it's supposed to work, in order to help defog better. It also has the side effect of keeping your AC compressor from sitting idle all winter and ensuring that your AC system circulates lubricating oil.

 

[Jonny-K5]

really? huh, learn something new every day...