I want to know if this is normal. When I switch the heater from Defrost to Defrost/Heater, my engine rev up quite a bit, actually forcing the car to go if I don't step on the brake hard. Is this normal or is there something wrong with my 91 Legacy AWD Auto non-turbo? Thanks in advance.

I want to know if this is normal. When I switch the heater from Defrost to Defrost/Heater, my engine rev up quite a bit, actually forcing the car to go if I don't step on the brake hard. Is this normal or is there something wrong with my 91 Legacy AWD Auto non-turbo? Thanks in advance.

The defroster run the AC compressor, Air conditioning take moisture out of the air allowing the defroster to de-fog the windows.

This is normal.

From some funny reason, it wouldn't do it when I switch from Heater to Defrost, only does it when switching from Defrost to Defrost/Heater (the bi button). Thanks for the info, though. It's good to know there's nothing wrong with my work car.

From some funny reason, it wouldn't do it when I switch from Heater to Defrost, only does it when switching from Defrost to Defrost/Heater (the bi button). Thanks for the info, though. It's good to know there's nothing wrong with my work car.

So when you switch to Defroster button the AC compressor does not kick on?

The engine rpms are going to jump up a little.....they shouldn't go way up. If you're in neutral and do the switching thing. What do the rpms do?

The engine rpms are going to jump up a little.....they shouldn't go way up. If you're in neutral and do the switching thing. What do the rpms do?

Going from Off to Defrost, the rpm does not rev up (I think), but from Defrost to Defrost/Heater, it would rev up. I will do a more thorough test switching between them and see what happens.